Class GenericServletWrapper
java.lang.Object
com.ibm.wsspi.webcontainer.servlet.GenericServletWrapper
- All Implemented Interfaces:
RequestProcessor
,IServletWrapper
A convenience class that implements IServletWrapper. This class must be
subclassed if IServletWrapper implementations want to leverage the webcontainer's
handling of the following:
-> Servlet lifecycle management
-> Event generation and firing
-> Request handling leveraging sessions and security
Subclasses usually override the handleRequest() method wherein they implement
logic specific to the container they are part of, and at the end call on
super.handleRequest() which then handles the actual dispatch to the servlet
and invokes the Servlet's service() method.
- Since:
- WAS6.0
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Constructor Summary
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Method Summary
Modifier and TypeMethodDescriptionvoid
Add a listener which will listen to the invalidation events for this wrapper instance.void
destroy()
This method will be invoked when the parent container wishes to destroy this IServletWrapper instance.long
This method will be called by the webcontainer's reaper mechanism which polls for the access times of the wrappers in its datastructures, and invalidates them if they have been inactive for a preconfigured amount of time.getName()
Returns the ServletConfig associated with the targetjavax.servlet.ServletContext
Returns the servlet context associated with this servlet wrapper.Returns the servlet name of the targetjavax.servlet.Servlet
Returns the target Servlet instanceReturns the current classloader which loaded (or will, in the future, load) the target.void
handleRequest
(javax.servlet.ServletRequest req, javax.servlet.ServletResponse res) Method that processes the request, and ultimately invokes the service() on the Servlet target.void
initialize
(IServletConfig config) Method that handles the initialization of this IServletWrapper instance.boolean
Returns whether the requested wrapper resource exists.boolean
void
load()
Loads the servlet and calls the Servlet's init method with the previously passed IServletConfig.void
Initializes this wrapper with the specified config.void
modifyTarget
(javax.servlet.Servlet s) void
void
void
Gracefully invalidates the target by overseeing its lifecycle (destroy()) This method must be called before the target is invalidated for reload.void
service
(javax.servlet.ServletRequest request, javax.servlet.ServletResponse response) void
setParent
(IServletContext parent) Sets the parent context for this servletwrappervoid
setTarget
(javax.servlet.Servlet target) Sets the target for this IServletWrapper.void
setTargetClassLoader
(ClassLoader loader) Instructs the underlying implementation to use the supplied class loader to instantiate the target instance.
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Constructor Details
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GenericServletWrapper
Public constructor. This contructor must be invoked from within the constructor of the subclass passing in the IServletContext so that the parent object can be constructed correctly.- Parameters:
parent
- The IServletContext that this IServletWrapper will be a part of- Throws:
Exception
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Method Details
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initialize
Method that handles the initialization of this IServletWrapper instance. Subclasses must call this by invoking super.initialize(config), so that the underlying target Servlet can be setup and initialized by calling its init() method (if specified in the config as loadAtStartUp).- Specified by:
initialize
in interfaceIServletWrapper
- Parameters:
config
- the IServletConfig associated with this IServletWrapper- Throws:
Exception
- See Also:
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handleRequest
public void handleRequest(javax.servlet.ServletRequest req, javax.servlet.ServletResponse res) throws Exception Method that processes the request, and ultimately invokes the service() on the Servlet target. Subclasses may override this method to put in additional logic (eg., reload/retranslation logic in the case of JSP containers). Subclasses must call this method by invoking super.handleRequest() if they want the webcontainer to handle initialization and servicing of the target in a proper way. An example scenario: class SimpleJSPServletWrapper extends GenericServletWrapper { ... public void handleRequest(ServletRequest req, ServletResponse res) { String jspFile = getFileFromRequest(req); // get the JSP target if (hasFileChangedOnDisk(jspFile)) { prepareForReload(); // invalidate the target and targetClassLoader setTargetClassLoader(null); setTarget(null); JSPServlet jsp = compileJSP(jspFile); ClassLoader loader = getLoaderForServlet(jsp); setTarget(jsp.getClassName()); setTargetClassLoader(loader); } super.handleRequest(req, res); } ... }- Specified by:
handleRequest
in interfaceIServletWrapper
- Specified by:
handleRequest
in interfaceRequestProcessor
- Throws:
Exception
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prepareForReload
public void prepareForReload()Gracefully invalidates the target by overseeing its lifecycle (destroy()) This method must be called before the target is invalidated for reload.- Specified by:
prepareForReload
in interfaceIServletWrapper
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getServletName
Returns the servlet name of the target- Specified by:
getServletName
in interfaceIServletWrapper
- Returns:
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getServletConfig
Returns the ServletConfig associated with the target- Specified by:
getServletConfig
in interfaceIServletWrapper
- Returns:
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getServletContext
public javax.servlet.ServletContext getServletContext()Description copied from interface:IServletWrapper
Returns the servlet context associated with this servlet wrapper.- Specified by:
getServletContext
in interfaceIServletWrapper
- Returns:
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setTargetClassLoader
Instructs the underlying implementation to use the supplied class loader to instantiate the target instance. Calling this method with a null, accompanied with a setTarget(null) will result in the current classloader being destroyed and garbage collected along with the target instance.- Specified by:
setTargetClassLoader
in interfaceIServletWrapper
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getTarget
public javax.servlet.Servlet getTarget()Returns the target Servlet instance- Specified by:
getTarget
in interfaceIServletWrapper
- Returns:
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getTargetClassLoader
Returns the current classloader which loaded (or will, in the future, load) the target.- Specified by:
getTargetClassLoader
in interfaceIServletWrapper
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setTarget
public void setTarget(javax.servlet.Servlet target) Sets the target for this IServletWrapper.- Specified by:
setTarget
in interfaceIServletWrapper
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addServletReferenceListener
Add a listener which will listen to the invalidation events for this wrapper instance. The invalidate() event will be fired only when the wrapper itself (not the target) is about to be destroyed by the parent container.- Specified by:
addServletReferenceListener
in interfaceIServletWrapper
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getLastAccessTime
public long getLastAccessTime()This method will be called by the webcontainer's reaper mechanism which polls for the access times of the wrappers in its datastructures, and invalidates them if they have been inactive for a preconfigured amount of time. Wrapper subclasses that do not want to be 'reaped' may override this method by returning the current system time.- Specified by:
getLastAccessTime
in interfaceIServletWrapper
- Returns:
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destroy
public void destroy()This method will be invoked when the parent container wishes to destroy this IServletWrapper instance. Thew subclasses may override this method to implement any resource clean up, but must invoke this method by calling super.destroy() inorder to correctly destroy the underlying target.- Specified by:
destroy
in interfaceIServletWrapper
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service
public void service(javax.servlet.ServletRequest request, javax.servlet.ServletResponse response) throws IOException, javax.servlet.ServletException - Specified by:
service
in interfaceIServletWrapper
- Throws:
IOException
javax.servlet.ServletException
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setParent
Description copied from interface:IServletWrapper
Sets the parent context for this servletwrapper- Specified by:
setParent
in interfaceIServletWrapper
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isAvailable
public boolean isAvailable()Returns whether the requested wrapper resource exists.- Specified by:
isAvailable
in interfaceIServletWrapper
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nameSpacePostInvoke
public void nameSpacePostInvoke() -
nameSpacePreInvoke
public void nameSpacePreInvoke() -
getName
- Specified by:
getName
in interfaceRequestProcessor
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isInternal
public boolean isInternal()- Specified by:
isInternal
in interfaceRequestProcessor
- Returns:
- boolean Returns true if this request processor is for internal use only
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loadOnStartupCheck
Description copied from interface:IServletWrapper
Initializes this wrapper with the specified config. Depending on the startup weight specified in the config, the underlying target Servlet will either be initialized within this call. NOTE: This initialization behaviour of the target Servlet can be controlled by calling the setStartUpWeight() method on the IServletConfig- Specified by:
loadOnStartupCheck
in interfaceIServletWrapper
- Throws:
Exception
- See Also:
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load
Description copied from interface:IServletWrapper
Loads the servlet and calls the Servlet's init method with the previously passed IServletConfig. One component that calls this is SIP.- Specified by:
load
in interfaceIServletWrapper
- Throws:
Exception
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modifyTarget
public void modifyTarget(javax.servlet.Servlet s) - Specified by:
modifyTarget
in interfaceIServletWrapper
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