Package jakarta.servlet

Class ServletInputStream

java.lang.Object

java.io.InputStream

jakarta.servlet.ServletInputStream

All Implemented Interfaces:

Closeable, AutoCloseable

public abstract class ServletInputStream
extends InputStream

Provides an input stream for reading binary data from a client request, including an efficient readLine method for reading data one line at a time. With some protocols, such as HTTP POST and PUT, a ServletInputStream object can be used to read data sent from the client.

A ServletInputStream object is normally retrieved via the ServletRequest.getInputStream() method.

This is an abstract class that a servlet container implements. Subclasses of this class must implement the java.io.InputStream.read() method.

See Also:

• ServletRequest

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	ServletInputStream()	Does nothing, because this is an abstract class.

Method Summary

Modifier and Type	Method	Description
abstract boolean	isFinished()	Returns true when all the data from the stream has been read else it returns false.
abstract boolean	isReady()	Returns true if data can be read without blocking else returns false.
int	readLine(byte[] b, int off, int len)	Reads the input stream, one line at a time.
abstract void	setReadListener(ReadListener readListener)	Instructs the ServletInputStream to invoke the provided ReadListener when it is possible to read

Methods inherited from class java.io.InputStream

available, close, mark, markSupported, nullInputStream, read, read, read, readAllBytes, readNBytes, readNBytes, reset, skip, skipNBytes, transferTo

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

ServletInputStream

protected ServletInputStream()

Does nothing, because this is an abstract class.

Method Details

readLine

public int readLine(byte[] b,
 int off,
 int len)
             throws IOException

Reads the input stream, one line at a time. Starting at an offset, reads bytes into an array, until it reads a certain number of bytes or reaches a newline character, which it reads into the array as well.

This method returns -1 if it reaches the end of the input stream before reading the maximum number of bytes.

Parameters:

b - an array of bytes into which data is read

off - an integer specifying the character at which this method begins reading

len - an integer specifying the maximum number of bytes to read

Returns:

an integer specifying the actual number of bytes read, or -1 if the end of the stream is reached

Throws:

IOException - if an input or output exception has occurred

isFinished

public abstract boolean isFinished()

Returns true when all the data from the stream has been read else it returns false.

Returns:

true when all data for this particular request has been read, otherwise returns false.

Since:

Servlet 3.1

isReady

public abstract boolean isReady()

Returns true if data can be read without blocking else returns false.

If this method returns false and a ReadListener has been set via setReadListener(ReadListener), then the container will subsequently invoke ReadListener.onDataAvailable() (or ReadListener.onAllDataRead()) once data (or EOF) has become available. Other than the initial call, ReadListener.onDataAvailable() will only be called if and only if this method is called and returns false.

Returns:

true if data can be obtained without blocking, otherwise returns false.

Since:

Servlet 3.1

See Also:

• ReadListener

setReadListener

public abstract void setReadListener(ReadListener readListener)

Instructs the ServletInputStream to invoke the provided ReadListener when it is possible to read

Parameters:

readListener - the ReadListener that should be notified when it's possible to read.

Throws:

IllegalStateException - if one of the following conditions is true

• the associated request is neither upgraded nor the async started
• setReadListener is called more than once within the scope of the same request.

NullPointerException - if readListener is null

Since:

Servlet 3.1