Package javax.servlet

Interface ServletContext



  • public interface ServletContext
    Defines a set of methods that a servlet uses to communicate with its servlet container, for example, to get the MIME type of a file, dispatch requests, or write to a log file.

    There is one context per "web application" per Java Virtual Machine. (A "web application" is a collection of servlets and content installed under a specific subset of the server's URL namespace such as /catalog and possibly installed via a .war file.)

    In the case of a web application marked "distributed" in its deployment descriptor, there will be one context instance for each virtual machine. In this situation, the context cannot be used as a location to share global information (because the information won't be truly global). Use an external resource like a database instead.

    The ServletContext object is contained within the ServletConfig object, which the Web server provides the servlet when the servlet is initialized.

    See Also:
    Servlet.getServletConfig(), ServletConfig.getServletContext()
    • Field Summary

      Fields 
      Modifier and Type Field Description
      static java.lang.String ORDERED_LIBS
      The name of the ServletContext attribute whose value (of type java.util.List<java.lang.String>) contains the list of names of JAR files in WEB-INF/lib ordered by their web fragment names (with possible exclusions if <absolute-ordering> without any <others/> is being used), or null if no absolute or relative ordering has been specified
      static java.lang.String TEMPDIR
      The name of the ServletContext attribute which stores the private temporary directory (of type java.io.File) provided by the servlet container for the ServletContext
    • Method Summary

      All Methods Instance Methods Abstract Methods Deprecated Methods 
      Modifier and Type Method Description
      FilterRegistration.Dynamic addFilter​(java.lang.String filterName, java.lang.Class<? extends Filter> filterClass)
      Adds the filter with the given name and class type to this servlet context.
      FilterRegistration.Dynamic addFilter​(java.lang.String filterName, java.lang.String className)
      Adds the filter with the given name and class name to this servlet context.
      FilterRegistration.Dynamic addFilter​(java.lang.String filterName, Filter filter)
      Registers the given filter instance with this ServletContext under the given filterName.
      ServletRegistration.Dynamic addJspFile​(java.lang.String servletName, java.lang.String jspFile)
      Adds the servlet with the given jsp file to this servlet context.
      void addListener​(java.lang.Class<? extends java.util.EventListener> listenerClass)
      Adds a listener of the given class type to this ServletContext.
      void addListener​(java.lang.String className)
      Adds the listener with the given class name to this ServletContext.
      <T extends java.util.EventListener>
      void
      addListener​(T t)
      Adds the given listener to this ServletContext.
      ServletRegistration.Dynamic addServlet​(java.lang.String servletName, java.lang.Class<? extends Servlet> servletClass)
      Adds the servlet with the given name and class type to this servlet context.
      ServletRegistration.Dynamic addServlet​(java.lang.String servletName, java.lang.String className)
      Adds the servlet with the given name and class name to this servlet context.
      ServletRegistration.Dynamic addServlet​(java.lang.String servletName, Servlet servlet)
      Registers the given servlet instance with this ServletContext under the given servletName.
      <T extends Filter>
      T
      createFilter​(java.lang.Class<T> clazz)
      Instantiates the given Filter class.
      <T extends java.util.EventListener>
      T
      createListener​(java.lang.Class<T> clazz)
      Instantiates the given EventListener class.
      <T extends Servlet>
      T
      createServlet​(java.lang.Class<T> clazz)
      Instantiates the given Servlet class.
      void declareRoles​(java.lang.String... roleNames)
      Declares role names that are tested using isUserInRole.
      java.lang.Object getAttribute​(java.lang.String name)
      Returns the servlet container attribute with the given name, or null if there is no attribute by that name.
      java.util.Enumeration<java.lang.String> getAttributeNames​()
      Returns an Enumeration containing the attribute names available within this ServletContext.
      java.lang.ClassLoader getClassLoader​()
      Gets the class loader of the web application represented by this ServletContext.
      ServletContext getContext​(java.lang.String uripath)
      Returns a ServletContext object that corresponds to a specified URL on the server.
      java.lang.String getContextPath​()
      Returns the context path of the web application.
      java.util.Set<SessionTrackingMode> getDefaultSessionTrackingModes​()
      Gets the session tracking modes that are supported by default for this ServletContext.
      int getEffectiveMajorVersion​()
      Gets the major version of the Servlet specification that the application represented by this ServletContext is based on.
      int getEffectiveMinorVersion​()
      Gets the minor version of the Servlet specification that the application represented by this ServletContext is based on.
      java.util.Set<SessionTrackingMode> getEffectiveSessionTrackingModes​()
      Gets the session tracking modes that are in effect for this ServletContext.
      FilterRegistration getFilterRegistration​(java.lang.String filterName)
      Gets the FilterRegistration corresponding to the filter with the given filterName.
      java.util.Map<java.lang.String,? extends FilterRegistration> getFilterRegistrations​()
      Gets a (possibly empty) Map of the FilterRegistration objects (keyed by filter name) corresponding to all filters registered with this ServletContext.
      java.lang.String getInitParameter​(java.lang.String name)
      Returns a String containing the value of the named context-wide initialization parameter, or null if the parameter does not exist.
      java.util.Enumeration<java.lang.String> getInitParameterNames​()
      Returns the names of the context's initialization parameters as an Enumeration of String objects, or an empty Enumeration if the context has no initialization parameters.
      JspConfigDescriptor getJspConfigDescriptor​()
      Gets the <jsp-config> related configuration that was aggregated from the web.xml and web-fragment.xml descriptor files of the web application represented by this ServletContext.
      int getMajorVersion​()
      Returns the major version of the Servlet API that this servlet container supports.
      java.lang.String getMimeType​(java.lang.String file)
      Returns the MIME type of the specified file, or null if the MIME type is not known.
      int getMinorVersion​()
      Returns the minor version of the Servlet API that this servlet container supports.
      RequestDispatcher getNamedDispatcher​(java.lang.String name)
      Returns a RequestDispatcher object that acts as a wrapper for the named servlet.
      java.lang.String getRealPath​(java.lang.String path)
      Gets the real path corresponding to the given virtual path.
      java.lang.String getRequestCharacterEncoding​()
      Gets the request character encoding that are supported by default for this ServletContext.
      RequestDispatcher getRequestDispatcher​(java.lang.String path)
      Returns a RequestDispatcher object that acts as a wrapper for the resource located at the given path.
      java.net.URL getResource​(java.lang.String path)
      Returns a URL to the resource that is mapped to the given path.
      java.io.InputStream getResourceAsStream​(java.lang.String path)
      Returns the resource located at the named path as an InputStream object.
      java.util.Set<java.lang.String> getResourcePaths​(java.lang.String path)
      Returns a directory-like listing of all the paths to resources within the web application whose longest sub-path matches the supplied path argument.
      java.lang.String getResponseCharacterEncoding​()
      Gets the response character encoding that are supported by default for this ServletContext.
      java.lang.String getServerInfo​()
      Returns the name and version of the servlet container on which the servlet is running.
      Servlet getServlet​(java.lang.String name)
      Deprecated. 
      As of Java Servlet API 2.1, with no direct replacement.

      This method was originally defined to retrieve a servlet from a ServletContext. In this version, this method always returns null and remains only to preserve binary compatibility. This method will be permanently removed in a future version of the Java Servlet API.

      In lieu of this method, servlets can share information using the ServletContext class and can perform shared business logic by invoking methods on common non-servlet classes.

      java.lang.String getServletContextName​()
      Returns the name of this web application corresponding to this ServletContext as specified in the deployment descriptor for this web application by the display-name element.
      java.util.Enumeration<java.lang.String> getServletNames​()
      Deprecated. 
      As of Java Servlet API 2.1, with no replacement.

      This method was originally defined to return an Enumeration of all the servlet names known to this context. In this version, this method always returns an empty Enumeration and remains only to preserve binary compatibility. This method will be permanently removed in a future version of the Java Servlet API.

      ServletRegistration getServletRegistration​(java.lang.String servletName)
      Gets the ServletRegistration corresponding to the servlet with the given servletName.
      java.util.Map<java.lang.String,? extends ServletRegistration> getServletRegistrations​()
      Gets a (possibly empty) Map of the ServletRegistration objects (keyed by servlet name) corresponding to all servlets registered with this ServletContext.
      java.util.Enumeration<Servlet> getServlets​()
      Deprecated. 
      As of Java Servlet API 2.0, with no replacement.

      This method was originally defined to return an Enumeration of all the servlets known to this servlet context. In this version, this method always returns an empty enumeration and remains only to preserve binary compatibility. This method will be permanently removed in a future version of the Java Servlet API.

      SessionCookieConfig getSessionCookieConfig​()
      Gets the SessionCookieConfig object through which various properties of the session tracking cookies created on behalf of this ServletContext may be configured.
      int getSessionTimeout​()
      Gets the session timeout in minutes that are supported by default for this ServletContext.
      java.lang.String getVirtualServerName​()
      Returns the configuration name of the logical host on which the ServletContext is deployed.
      void log​(java.lang.Exception exception, java.lang.String msg)
      Deprecated. 
      As of Java Servlet API 2.1, use log(String message, Throwable throwable) instead.

      This method was originally defined to write an exception's stack trace and an explanatory error message to the servlet log file.

      void log​(java.lang.String msg)
      Writes the specified message to a servlet log file, usually an event log.
      void log​(java.lang.String message, java.lang.Throwable throwable)
      Writes an explanatory message and a stack trace for a given Throwable exception to the servlet log file.
      void removeAttribute​(java.lang.String name)
      Removes the attribute with the given name from this ServletContext.
      void setAttribute​(java.lang.String name, java.lang.Object object)
      Binds an object to a given attribute name in this ServletContext.
      boolean setInitParameter​(java.lang.String name, java.lang.String value)
      Sets the context initialization parameter with the given name and value on this ServletContext.
      void setRequestCharacterEncoding​(java.lang.String encoding)
      Sets the request character encoding for this ServletContext.
      void setResponseCharacterEncoding​(java.lang.String encoding)
      Sets the response character encoding for this ServletContext.
      void setSessionTimeout​(int sessionTimeout)
      Sets the session timeout in minutes for this ServletContext.
      void setSessionTrackingModes​(java.util.Set<SessionTrackingMode> sessionTrackingModes)
      Sets the session tracking modes that are to become effective for this ServletContext.
    • Field Detail

      • TEMPDIR

        static final java.lang.String TEMPDIR
        The name of the ServletContext attribute which stores the private temporary directory (of type java.io.File) provided by the servlet container for the ServletContext
        See Also:
        Constant Field Values
      • ORDERED_LIBS

        static final java.lang.String ORDERED_LIBS
        The name of the ServletContext attribute whose value (of type java.util.List<java.lang.String>) contains the list of names of JAR files in WEB-INF/lib ordered by their web fragment names (with possible exclusions if <absolute-ordering> without any <others/> is being used), or null if no absolute or relative ordering has been specified
        See Also:
        Constant Field Values
    • Method Detail

      • getContextPath

        java.lang.String getContextPath​()
        Returns the context path of the web application.

        The context path is the portion of the request URI that is used to select the context of the request. The context path always comes first in a request URI. If this context is the "root" context rooted at the base of the Web server's URL name space, this path will be an empty string. Otherwise, if the context is not rooted at the root of the server's name space, the path starts with a / character but does not end with a / character.

        It is possible that a servlet container may match a context by more than one context path. In such cases the HttpServletRequest.getContextPath() will return the actual context path used by the request and it may differ from the path returned by this method. The context path returned by this method should be considered as the prime or preferred context path of the application.

        Returns:
        The context path of the web application, or "" for the root context
        Since:
        Servlet 2.5
        See Also:
        HttpServletRequest.getContextPath()
      • getContext

        ServletContext getContext​(java.lang.String uripath)
        Returns a ServletContext object that corresponds to a specified URL on the server.

        This method allows servlets to gain access to the context for various parts of the server, and as needed obtain RequestDispatcher objects from the context. The given path must be begin with /, is interpreted relative to the server's document root and is matched against the context roots of other web applications hosted on this container.

        In a security conscious environment, the servlet container may return null for a given URL.

        Parameters:
        uripath - a String specifying the context path of another web application in the container.
        Returns:
        the ServletContext object that corresponds to the named URL, or null if either none exists or the container wishes to restrict this access.
        See Also:
        RequestDispatcher
      • getMajorVersion

        int getMajorVersion​()
        Returns the major version of the Servlet API that this servlet container supports. All implementations that comply with Version 4.0 must have this method return the integer 4.
        Returns:
        4
      • getMinorVersion

        int getMinorVersion​()
        Returns the minor version of the Servlet API that this servlet container supports. All implementations that comply with Version 4.0 must have this method return the integer 0.
        Returns:
        0
      • getEffectiveMajorVersion

        int getEffectiveMajorVersion​()
        Gets the major version of the Servlet specification that the application represented by this ServletContext is based on.

        The value returned may be different from getMajorVersion(), which returns the major version of the Servlet specification supported by the Servlet container.

        Returns:
        the major version of the Servlet specification that the application represented by this ServletContext is based on
        Throws:
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 3.0
      • getEffectiveMinorVersion

        int getEffectiveMinorVersion​()
        Gets the minor version of the Servlet specification that the application represented by this ServletContext is based on.

        The value returned may be different from getMinorVersion(), which returns the minor version of the Servlet specification supported by the Servlet container.

        Returns:
        the minor version of the Servlet specification that the application represented by this ServletContext is based on
        Throws:
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 3.0
      • getMimeType

        java.lang.String getMimeType​(java.lang.String file)
        Returns the MIME type of the specified file, or null if the MIME type is not known. The MIME type is determined by the configuration of the servlet container, and may be specified in a web application deployment descriptor. Common MIME types include text/html and image/gif.
        Parameters:
        file - a String specifying the name of a file
        Returns:
        a String specifying the file's MIME type
      • getResourcePaths

        java.util.Set<java.lang.String> getResourcePaths​(java.lang.String path)
        Returns a directory-like listing of all the paths to resources within the web application whose longest sub-path matches the supplied path argument.

        Paths indicating subdirectory paths end with a /.

        The returned paths are all relative to the root of the web application, or relative to the /META-INF/resources directory of a JAR file inside the web application's /WEB-INF/lib directory, and have a leading /.

        The returned set is not backed by the ServletContext object, so changes in the returned set are not reflected in the ServletContext object, and vice-versa.

        For example, for a web application containing:

        
           /welcome.html
           /catalog/index.html
           /catalog/products.html
           /catalog/offers/books.html
           /catalog/offers/music.html
           /customer/login.jsp
           /WEB-INF/web.xml
           /WEB-INF/classes/com.acme.OrderServlet.class
           /WEB-INF/lib/catalog.jar!/META-INF/resources/catalog/moreOffers/books.html
         
        getResourcePaths("/") would return {"/welcome.html", "/catalog/", "/customer/", "/WEB-INF/"}, and getResourcePaths("/catalog/") would return {"/catalog/index.html", "/catalog/products.html", "/catalog/offers/", "/catalog/moreOffers/"}.
        Parameters:
        path - the partial path used to match the resources, which must start with a /
        Returns:
        a Set containing the directory listing, or null if there are no resources in the web application whose path begins with the supplied path.
        Since:
        Servlet 2.3
      • getResource

        java.net.URL getResource​(java.lang.String path)
                          throws java.net.MalformedURLException
        Returns a URL to the resource that is mapped to the given path.

        The path must begin with a / and is interpreted as relative to the current context root, or relative to the /META-INF/resources directory of a JAR file inside the web application's /WEB-INF/lib directory. This method will first search the document root of the web application for the requested resource, before searching any of the JAR files inside /WEB-INF/lib. The order in which the JAR files inside /WEB-INF/lib are searched is undefined.

        This method allows the servlet container to make a resource available to servlets from any source. Resources can be located on a local or remote file system, in a database, or in a .war file.

        The servlet container must implement the URL handlers and URLConnection objects that are necessary to access the resource.

        This method returns null if no resource is mapped to the pathname.

        Some containers may allow writing to the URL returned by this method using the methods of the URL class.

        The resource content is returned directly, so be aware that requesting a .jsp page returns the JSP source code. Use a RequestDispatcher instead to include results of an execution.

        This method has a different purpose than java.lang.Class.getResource, which looks up resources based on a class loader. This method does not use class loaders.

        Parameters:
        path - a String specifying the path to the resource
        Returns:
        the resource located at the named path, or null if there is no resource at that path
        Throws:
        java.net.MalformedURLException - if the pathname is not given in the correct form
      • getResourceAsStream

        java.io.InputStream getResourceAsStream​(java.lang.String path)
        Returns the resource located at the named path as an InputStream object.

        The data in the InputStream can be of any type or length. The path must be specified according to the rules given in getResource. This method returns null if no resource exists at the specified path.

        Meta-information such as content length and content type that is available via getResource method is lost when using this method.

        The servlet container must implement the URL handlers and URLConnection objects necessary to access the resource.

        This method is different from java.lang.Class.getResourceAsStream, which uses a class loader. This method allows servlet containers to make a resource available to a servlet from any location, without using a class loader.

        Parameters:
        path - a String specifying the path to the resource
        Returns:
        the InputStream returned to the servlet, or null if no resource exists at the specified path
      • getRequestDispatcher

        RequestDispatcher getRequestDispatcher​(java.lang.String path)
        Returns a RequestDispatcher object that acts as a wrapper for the resource located at the given path. A RequestDispatcher object can be used to forward a request to the resource or to include the resource in a response. The resource can be dynamic or static.

        The pathname must begin with a / and is interpreted as relative to the current context root. Use getContext to obtain a RequestDispatcher for resources in foreign contexts.

        This method returns null if the ServletContext cannot return a RequestDispatcher.

        Parameters:
        path - a String specifying the pathname to the resource
        Returns:
        a RequestDispatcher object that acts as a wrapper for the resource at the specified path, or null if the ServletContext cannot return a RequestDispatcher
        See Also:
        RequestDispatcher, getContext(java.lang.String)
      • getNamedDispatcher

        RequestDispatcher getNamedDispatcher​(java.lang.String name)
        Returns a RequestDispatcher object that acts as a wrapper for the named servlet.

        Servlets (and JSP pages also) may be given names via server administration or via a web application deployment descriptor. A servlet instance can determine its name using ServletConfig.getServletName().

        This method returns null if the ServletContext cannot return a RequestDispatcher for any reason.

        Parameters:
        name - a String specifying the name of a servlet to wrap
        Returns:
        a RequestDispatcher object that acts as a wrapper for the named servlet, or null if the ServletContext cannot return a RequestDispatcher
        See Also:
        RequestDispatcher, getContext(java.lang.String), ServletConfig.getServletName()
      • getServlet

        @Deprecated
        Servlet getServlet​(java.lang.String name)
                    throws ServletException
        Deprecated. As of Java Servlet API 2.1, with no direct replacement.

        This method was originally defined to retrieve a servlet from a ServletContext. In this version, this method always returns null and remains only to preserve binary compatibility. This method will be permanently removed in a future version of the Java Servlet API.

        In lieu of this method, servlets can share information using the ServletContext class and can perform shared business logic by invoking methods on common non-servlet classes.

        Parameters:
        name - the servlet name
        Returns:
        the javax.servlet.Servlet Servlet with the given name
        Throws:
        ServletException - if an exception has occurred that interfaces with servlet's normal operation
      • getServlets

        @Deprecated
        java.util.Enumeration<Servlet> getServlets​()
        Deprecated. As of Java Servlet API 2.0, with no replacement.

        This method was originally defined to return an Enumeration of all the servlets known to this servlet context. In this version, this method always returns an empty enumeration and remains only to preserve binary compatibility. This method will be permanently removed in a future version of the Java Servlet API.

        Returns:
        an Enumeration of javax.servlet.Servlet Servlet
      • getServletNames

        @Deprecated
        java.util.Enumeration<java.lang.String> getServletNames​()
        Deprecated. As of Java Servlet API 2.1, with no replacement.

        This method was originally defined to return an Enumeration of all the servlet names known to this context. In this version, this method always returns an empty Enumeration and remains only to preserve binary compatibility. This method will be permanently removed in a future version of the Java Servlet API.

        Returns:
        an Enumeration of javax.servlet.Servlet Servlet names
      • log

        void log​(java.lang.String msg)
        Writes the specified message to a servlet log file, usually an event log. The name and type of the servlet log file is specific to the servlet container.
        Parameters:
        msg - a String specifying the message to be written to the log file
      • log

        @Deprecated
        void log​(java.lang.Exception exception,
                 java.lang.String msg)
        Deprecated. As of Java Servlet API 2.1, use log(String message, Throwable throwable) instead.

        This method was originally defined to write an exception's stack trace and an explanatory error message to the servlet log file.

        Parameters:
        exception - the Exception error
        msg - a String that describes the exception
      • log

        void log​(java.lang.String message,
                 java.lang.Throwable throwable)
        Writes an explanatory message and a stack trace for a given Throwable exception to the servlet log file. The name and type of the servlet log file is specific to the servlet container, usually an event log.
        Parameters:
        message - a String that describes the error or exception
        throwable - the Throwable error or exception
      • getRealPath

        java.lang.String getRealPath​(java.lang.String path)
        Gets the real path corresponding to the given virtual path.

        For example, if path is equal to /index.html, this method will return the absolute file path on the server's filesystem to which a request of the form http://<host>:<port>/<contextPath>/index.html would be mapped, where <contextPath> corresponds to the context path of this ServletContext.

        The real path returned will be in a form appropriate to the computer and operating system on which the servlet container is running, including the proper path separators.

        Resources inside the /META-INF/resources directories of JAR files bundled in the application's /WEB-INF/lib directory must be considered only if the container has unpacked them from their containing JAR file, in which case the path to the unpacked location must be returned.

        This method returns null if the servlet container is unable to translate the given virtual path to a real path.

        Parameters:
        path - the virtual path to be translated to a real path
        Returns:
        the real path, or null if the translation cannot be performed
      • getServerInfo

        java.lang.String getServerInfo​()
        Returns the name and version of the servlet container on which the servlet is running.

        The form of the returned string is servername/versionnumber. For example, the JavaServer Web Development Kit may return the string JavaServer Web Dev Kit/1.0.

        The servlet container may return other optional information after the primary string in parentheses, for example, JavaServer Web Dev Kit/1.0 (JDK 1.1.6; Windows NT 4.0 x86).

        Returns:
        a String containing at least the servlet container name and version number
      • getInitParameter

        java.lang.String getInitParameter​(java.lang.String name)
        Returns a String containing the value of the named context-wide initialization parameter, or null if the parameter does not exist.

        This method can make available configuration information useful to an entire web application. For example, it can provide a webmaster's email address or the name of a system that holds critical data.

        Parameters:
        name - a String containing the name of the parameter whose value is requested
        Returns:
        a String containing the value of the context's initialization parameter, or null if the context's initialization parameter does not exist.
        Throws:
        java.lang.NullPointerException - if the argument name is null
        See Also:
        ServletConfig.getInitParameter(java.lang.String)
      • getInitParameterNames

        java.util.Enumeration<java.lang.String> getInitParameterNames​()
        Returns the names of the context's initialization parameters as an Enumeration of String objects, or an empty Enumeration if the context has no initialization parameters.
        Returns:
        an Enumeration of String objects containing the names of the context's initialization parameters
        See Also:
        ServletConfig.getInitParameter(java.lang.String)
      • setInitParameter

        boolean setInitParameter​(java.lang.String name,
                                 java.lang.String value)
        Sets the context initialization parameter with the given name and value on this ServletContext.
        Parameters:
        name - the name of the context initialization parameter to set
        value - the value of the context initialization parameter to set
        Returns:
        true if the context initialization parameter with the given name and value was set successfully on this ServletContext, and false if it was not set because this ServletContext already contains a context initialization parameter with a matching name
        Throws:
        java.lang.IllegalStateException - if this ServletContext has already been initialized
        java.lang.NullPointerException - if the name parameter is null
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 3.0
      • getAttribute

        java.lang.Object getAttribute​(java.lang.String name)
        Returns the servlet container attribute with the given name, or null if there is no attribute by that name.

        An attribute allows a servlet container to give the servlet additional information not already provided by this interface. See your server documentation for information about its attributes. A list of supported attributes can be retrieved using getAttributeNames.

        The attribute is returned as a java.lang.Object or some subclass.

        Attribute names should follow the same convention as package names. The Java Servlet API specification reserves names matching java.*, javax.*, and sun.*.

        Parameters:
        name - a String specifying the name of the attribute
        Returns:
        an Object containing the value of the attribute, or null if no attribute exists matching the given name.
        Throws:
        java.lang.NullPointerException - if the argument name is null
        See Also:
        getAttributeNames()
      • getAttributeNames

        java.util.Enumeration<java.lang.String> getAttributeNames​()
        Returns an Enumeration containing the attribute names available within this ServletContext.

        Use the getAttribute(java.lang.String) method with an attribute name to get the value of an attribute.

        Returns:
        an Enumeration of attribute names
        See Also:
        getAttribute(java.lang.String)
      • setAttribute

        void setAttribute​(java.lang.String name,
                          java.lang.Object object)
        Binds an object to a given attribute name in this ServletContext. If the name specified is already used for an attribute, this method will replace the attribute with the new to the new attribute.

        If listeners are configured on the ServletContext the container notifies them accordingly.

        If a null value is passed, the effect is the same as calling removeAttribute().

        Attribute names should follow the same convention as package names. The Java Servlet API specification reserves names matching java.*, javax.*, and sun.*.

        Parameters:
        name - a String specifying the name of the attribute
        object - an Object representing the attribute to be bound
        Throws:
        java.lang.NullPointerException - if the name parameter is null
      • removeAttribute

        void removeAttribute​(java.lang.String name)
        Removes the attribute with the given name from this ServletContext. After removal, subsequent calls to getAttribute(java.lang.String) to retrieve the attribute's value will return null.

        If listeners are configured on the ServletContext the container notifies them accordingly.

        Parameters:
        name - a String specifying the name of the attribute to be removed
      • getServletContextName

        java.lang.String getServletContextName​()
        Returns the name of this web application corresponding to this ServletContext as specified in the deployment descriptor for this web application by the display-name element.
        Returns:
        The name of the web application or null if no name has been declared in the deployment descriptor.
        Since:
        Servlet 2.3
      • addServlet

        ServletRegistration.Dynamic addServlet​(java.lang.String servletName,
                                               java.lang.String className)
        Adds the servlet with the given name and class name to this servlet context.

        The registered servlet may be further configured via the returned ServletRegistration object.

        The specified className will be loaded using the classloader associated with the application represented by this ServletContext.

        If this ServletContext already contains a preliminary ServletRegistration for a servlet with the given servletName, it will be completed (by assigning the given className to it) and returned.

        This method introspects the class with the given className for the ServletSecurity, MultipartConfig, javax.annotation.security.RunAs, and javax.annotation.security.DeclareRoles annotations. In addition, this method supports resource injection if the class with the given className represents a Managed Bean. See the Java EE platform and JSR 299 specifications for additional details about Managed Beans and resource injection.

        Parameters:
        servletName - the name of the servlet
        className - the fully qualified class name of the servlet
        Returns:
        a ServletRegistration object that may be used to further configure the registered servlet, or null if this ServletContext already contains a complete ServletRegistration for a servlet with the given servletName
        Throws:
        java.lang.IllegalStateException - if this ServletContext has already been initialized
        java.lang.IllegalArgumentException - if servletName is null or an empty String
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 3.0
      • addServlet

        ServletRegistration.Dynamic addServlet​(java.lang.String servletName,
                                               Servlet servlet)
        Registers the given servlet instance with this ServletContext under the given servletName.

        The registered servlet may be further configured via the returned ServletRegistration object.

        If this ServletContext already contains a preliminary ServletRegistration for a servlet with the given servletName, it will be completed (by assigning the class name of the given servlet instance to it) and returned.

        Parameters:
        servletName - the name of the servlet
        servlet - the servlet instance to register
        Returns:
        a ServletRegistration object that may be used to further configure the given servlet, or null if this ServletContext already contains a complete ServletRegistration for a servlet with the given servletName or if the same servlet instance has already been registered with this or another ServletContext in the same container
        Throws:
        java.lang.IllegalStateException - if this ServletContext has already been initialized
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        java.lang.IllegalArgumentException - if the given servlet instance implements SingleThreadModel, or servletName is null or an empty String
        Since:
        Servlet 3.0
      • addServlet

        ServletRegistration.Dynamic addServlet​(java.lang.String servletName,
                                               java.lang.Class<? extends Servlet> servletClass)
        Adds the servlet with the given name and class type to this servlet context.

        The registered servlet may be further configured via the returned ServletRegistration object.

        If this ServletContext already contains a preliminary ServletRegistration for a servlet with the given servletName, it will be completed (by assigning the name of the given servletClass to it) and returned.

        This method introspects the given servletClass for the ServletSecurity, MultipartConfig, javax.annotation.security.RunAs, and javax.annotation.security.DeclareRoles annotations. In addition, this method supports resource injection if the given servletClass represents a Managed Bean. See the Java EE platform and JSR 299 specifications for additional details about Managed Beans and resource injection.

        Parameters:
        servletName - the name of the servlet
        servletClass - the class object from which the servlet will be instantiated
        Returns:
        a ServletRegistration object that may be used to further configure the registered servlet, or null if this ServletContext already contains a complete ServletRegistration for the given servletName
        Throws:
        java.lang.IllegalStateException - if this ServletContext has already been initialized
        java.lang.IllegalArgumentException - if servletName is null or an empty String
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 3.0
      • addJspFile

        ServletRegistration.Dynamic addJspFile​(java.lang.String servletName,
                                               java.lang.String jspFile)
        Adds the servlet with the given jsp file to this servlet context.

        The registered servlet may be further configured via the returned ServletRegistration object.

        If this ServletContext already contains a preliminary ServletRegistration for a servlet with the given servletName, it will be completed (by assigning the given jspFile to it) and returned.

        Parameters:
        servletName - the name of the servlet
        jspFile - the full path to a JSP file within the web application beginning with a `/'.
        Returns:
        a ServletRegistration object that may be used to further configure the registered servlet, or null if this ServletContext already contains a complete ServletRegistration for a servlet with the given servletName
        Throws:
        java.lang.IllegalStateException - if this ServletContext has already been initialized
        java.lang.IllegalArgumentException - if servletName is null or an empty String
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 4.0
      • createServlet

        <T extends Servlet> T createServlet​(java.lang.Class<T> clazz)
                                     throws ServletException
        Instantiates the given Servlet class.

        The returned Servlet instance may be further customized before it is registered with this ServletContext via a call to addServlet(String,Servlet).

        The given Servlet class must define a zero argument constructor, which is used to instantiate it.

        This method introspects the given clazz for the following annotations: ServletSecurity, MultipartConfig, javax.annotation.security.RunAs, and javax.annotation.security.DeclareRoles. In addition, this method supports resource injection if the given clazz represents a Managed Bean. See the Java EE platform and JSR 299 specifications for additional details about Managed Beans and resource injection.

        Type Parameters:
        T - the class of the Servlet to create
        Parameters:
        clazz - the Servlet class to instantiate
        Returns:
        the new Servlet instance
        Throws:
        ServletException - if the given clazz fails to be instantiated
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 3.0
      • getServletRegistration

        ServletRegistration getServletRegistration​(java.lang.String servletName)
        Gets the ServletRegistration corresponding to the servlet with the given servletName.
        Parameters:
        servletName - the name of a servlet
        Returns:
        the (complete or preliminary) ServletRegistration for the servlet with the given servletName, or null if no ServletRegistration exists under that name
        Throws:
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 3.0
      • getServletRegistrations

        java.util.Map<java.lang.String,? extends ServletRegistration> getServletRegistrations​()
        Gets a (possibly empty) Map of the ServletRegistration objects (keyed by servlet name) corresponding to all servlets registered with this ServletContext.

        The returned Map includes the ServletRegistration objects corresponding to all declared and annotated servlets, as well as the ServletRegistration objects corresponding to all servlets that have been added via one of the addServlet and addJspFile methods.

        If permitted, any changes to the returned Map must not affect this ServletContext.

        Returns:
        Map of the (complete and preliminary) ServletRegistration objects corresponding to all servlets currently registered with this ServletContext
        Throws:
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 3.0
      • addFilter

        FilterRegistration.Dynamic addFilter​(java.lang.String filterName,
                                             java.lang.String className)
        Adds the filter with the given name and class name to this servlet context.

        The registered filter may be further configured via the returned FilterRegistration object.

        The specified className will be loaded using the classloader associated with the application represented by this ServletContext.

        If this ServletContext already contains a preliminary FilterRegistration for a filter with the given filterName, it will be completed (by assigning the given className to it) and returned.

        This method supports resource injection if the class with the given className represents a Managed Bean. See the Java EE platform and JSR 299 specifications for additional details about Managed Beans and resource injection.

        Parameters:
        filterName - the name of the filter
        className - the fully qualified class name of the filter
        Returns:
        a FilterRegistration object that may be used to further configure the registered filter, or null if this ServletContext already contains a complete FilterRegistration for a filter with the given filterName
        Throws:
        java.lang.IllegalStateException - if this ServletContext has already been initialized
        java.lang.IllegalArgumentException - if filterName is null or an empty String
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 3.0
      • addFilter

        FilterRegistration.Dynamic addFilter​(java.lang.String filterName,
                                             Filter filter)
        Registers the given filter instance with this ServletContext under the given filterName.

        The registered filter may be further configured via the returned FilterRegistration object.

        If this ServletContext already contains a preliminary FilterRegistration for a filter with the given filterName, it will be completed (by assigning the class name of the given filter instance to it) and returned.

        Parameters:
        filterName - the name of the filter
        filter - the filter instance to register
        Returns:
        a FilterRegistration object that may be used to further configure the given filter, or null if this ServletContext already contains a complete FilterRegistration for a filter with the given filterName or if the same filter instance has already been registered with this or another ServletContext in the same container
        Throws:
        java.lang.IllegalStateException - if this ServletContext has already been initialized
        java.lang.IllegalArgumentException - if filterName is null or an empty String
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 3.0
      • addFilter

        FilterRegistration.Dynamic addFilter​(java.lang.String filterName,
                                             java.lang.Class<? extends Filter> filterClass)
        Adds the filter with the given name and class type to this servlet context.

        The registered filter may be further configured via the returned FilterRegistration object.

        If this ServletContext already contains a preliminary FilterRegistration for a filter with the given filterName, it will be completed (by assigning the name of the given filterClass to it) and returned.

        This method supports resource injection if the given filterClass represents a Managed Bean. See the Java EE platform and JSR 299 specifications for additional details about Managed Beans and resource injection.

        Parameters:
        filterName - the name of the filter
        filterClass - the class object from which the filter will be instantiated
        Returns:
        a FilterRegistration object that may be used to further configure the registered filter, or null if this ServletContext already contains a complete FilterRegistration for a filter with the given filterName
        Throws:
        java.lang.IllegalStateException - if this ServletContext has already been initialized
        java.lang.IllegalArgumentException - if filterName is null or an empty String
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 3.0
      • createFilter

        <T extends Filter> T createFilter​(java.lang.Class<T> clazz)
                                   throws ServletException
        Instantiates the given Filter class.

        The returned Filter instance may be further customized before it is registered with this ServletContext via a call to addFilter(String,Filter).

        The given Filter class must define a zero argument constructor, which is used to instantiate it.

        This method supports resource injection if the given clazz represents a Managed Bean. See the Java EE platform and JSR 299 specifications for additional details about Managed Beans and resource injection.

        Type Parameters:
        T - the class of the Filter to create
        Parameters:
        clazz - the Filter class to instantiate
        Returns:
        the new Filter instance
        Throws:
        ServletException - if the given clazz fails to be instantiated
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 3.0
      • getFilterRegistration

        FilterRegistration getFilterRegistration​(java.lang.String filterName)
        Gets the FilterRegistration corresponding to the filter with the given filterName.
        Parameters:
        filterName - the name of a filter
        Returns:
        the (complete or preliminary) FilterRegistration for the filter with the given filterName, or null if no FilterRegistration exists under that name
        Throws:
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 3.0
      • getFilterRegistrations

        java.util.Map<java.lang.String,? extends FilterRegistration> getFilterRegistrations​()
        Gets a (possibly empty) Map of the FilterRegistration objects (keyed by filter name) corresponding to all filters registered with this ServletContext.

        The returned Map includes the FilterRegistration objects corresponding to all declared and annotated filters, as well as the FilterRegistration objects corresponding to all filters that have been added via one of the addFilter methods.

        Any changes to the returned Map must not affect this ServletContext.

        Returns:
        Map of the (complete and preliminary) FilterRegistration objects corresponding to all filters currently registered with this ServletContext
        Throws:
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 3.0
      • getSessionCookieConfig

        SessionCookieConfig getSessionCookieConfig​()
        Gets the SessionCookieConfig object through which various properties of the session tracking cookies created on behalf of this ServletContext may be configured.

        Repeated invocations of this method will return the same SessionCookieConfig instance.

        Returns:
        the SessionCookieConfig object through which various properties of the session tracking cookies created on behalf of this ServletContext may be configured
        Throws:
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 3.0
      • setSessionTrackingModes

        void setSessionTrackingModes​(java.util.Set<SessionTrackingMode> sessionTrackingModes)
        Sets the session tracking modes that are to become effective for this ServletContext.

        The given sessionTrackingModes replaces any session tracking modes set by a previous invocation of this method on this ServletContext.

        Parameters:
        sessionTrackingModes - the set of session tracking modes to become effective for this ServletContext
        Throws:
        java.lang.IllegalStateException - if this ServletContext has already been initialized
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        java.lang.IllegalArgumentException - if sessionTrackingModes specifies a combination of SessionTrackingMode.SSL with a session tracking mode other than SessionTrackingMode.SSL, or if sessionTrackingModes specifies a session tracking mode that is not supported by the servlet container
        Since:
        Servlet 3.0
      • getDefaultSessionTrackingModes

        java.util.Set<SessionTrackingMode> getDefaultSessionTrackingModes​()
        Gets the session tracking modes that are supported by default for this ServletContext.

        The returned set is not backed by the ServletContext object, so changes in the returned set are not reflected in the ServletContext object, and vice-versa.

        Returns:
        set of the session tracking modes supported by default for this ServletContext
        Throws:
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 3.0
      • getEffectiveSessionTrackingModes

        java.util.Set<SessionTrackingMode> getEffectiveSessionTrackingModes​()
        Gets the session tracking modes that are in effect for this ServletContext.

        The session tracking modes in effect are those provided to setSessionTrackingModes.

        The returned set is not backed by the ServletContext object, so changes in the returned set are not reflected in the ServletContext object, and vice-versa.

        Returns:
        set of the session tracking modes in effect for this ServletContext
        Throws:
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 3.0
      • getJspConfigDescriptor

        JspConfigDescriptor getJspConfigDescriptor​()
        Gets the <jsp-config> related configuration that was aggregated from the web.xml and web-fragment.xml descriptor files of the web application represented by this ServletContext.
        Returns:
        the <jsp-config> related configuration that was aggregated from the web.xml and web-fragment.xml descriptor files of the web application represented by this ServletContext, or null if no such configuration exists
        Throws:
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 3.0
        See Also:
        JspConfigDescriptor
      • getClassLoader

        java.lang.ClassLoader getClassLoader​()
        Gets the class loader of the web application represented by this ServletContext.

        If a security manager exists, and the caller's class loader is not the same as, or an ancestor of the requested class loader, then the security manager's checkPermission method is called with a RuntimePermission("getClassLoader") permission to check whether access to the requested class loader should be granted.

        Returns:
        the class loader of the web application represented by this ServletContext
        Throws:
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        java.lang.SecurityException - if a security manager denies access to the requested class loader
        Since:
        Servlet 3.0
      • declareRoles

        void declareRoles​(java.lang.String... roleNames)
        Declares role names that are tested using isUserInRole.

        Roles that are implicitly declared as a result of their use within the setServletSecurity or setRunAsRole methods of the ServletRegistration interface need not be declared.

        Parameters:
        roleNames - the role names being declared
        Throws:
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        java.lang.IllegalArgumentException - if any of the argument roleNames is null or the empty string
        java.lang.IllegalStateException - if the ServletContext has already been initialized
        Since:
        Servlet 3.0
      • getVirtualServerName

        java.lang.String getVirtualServerName​()
        Returns the configuration name of the logical host on which the ServletContext is deployed. Servlet containers may support multiple logical hosts. This method must return the same name for all the servlet contexts deployed on a logical host, and the name returned by this method must be distinct, stable per logical host, and suitable for use in associating server configuration information with the logical host. The returned value is NOT expected or required to be equivalent to a network address or hostname of the logical host.
        Returns:
        a String containing the configuration name of the logical host on which the servlet context is deployed.
        Throws:
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 3.1
      • setSessionTimeout

        void setSessionTimeout​(int sessionTimeout)
        Sets the session timeout in minutes for this ServletContext.
        Parameters:
        sessionTimeout - session timeout in minutes
        Throws:
        java.lang.IllegalStateException - if this ServletContext has already been initialized
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 4.0
      • getRequestCharacterEncoding

        java.lang.String getRequestCharacterEncoding​()
        Gets the request character encoding that are supported by default for this ServletContext. This method returns null if no request encoding character encoding has been specified in deployment descriptor or container specific configuration (for all web applications in the container).
        Returns:
        the request character encoding that are supported by default for this ServletContext
        Throws:
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 4.0
      • setRequestCharacterEncoding

        void setRequestCharacterEncoding​(java.lang.String encoding)
        Sets the request character encoding for this ServletContext.
        Parameters:
        encoding - request character encoding
        Throws:
        java.lang.IllegalStateException - if this ServletContext has already been initialized
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 4.0
      • getResponseCharacterEncoding

        java.lang.String getResponseCharacterEncoding​()
        Gets the response character encoding that are supported by default for this ServletContext. This method returns null if no response encoding character encoding has been specified in deployment descriptor or container specific configuration (for all web applications in the container).
        Returns:
        the request character encoding that are supported by default for this ServletContext
        Throws:
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 4.0
      • setResponseCharacterEncoding

        void setResponseCharacterEncoding​(java.lang.String encoding)
        Sets the response character encoding for this ServletContext.
        Parameters:
        encoding - response character encoding
        Throws:
        java.lang.IllegalStateException - if this ServletContext has already been initialized
        java.lang.UnsupportedOperationException - if this ServletContext was passed to the ServletContextListener.contextInitialized(javax.servlet.ServletContextEvent) method of a ServletContextListener that was neither declared in web.xml or web-fragment.xml, nor annotated with WebListener
        Since:
        Servlet 4.0