Class ServletInputStream

java.lang.Object

java.io.InputStream

javax.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()	Has the end of this InputStream been reached?
abstract boolean	isReady()	Can data be read from this InputStream without blocking?
int	readLine(byte[] b, int off, int len)	Reads the input stream, one line at a time.
abstract void	setReadListener(ReadListener listener)	Sets the ReadListener for this ServletInputStream and thereby switches to non-blocking IO.

Methods inherited from class InputStream

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

Methods inherited from class 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()

Has the end of this InputStream been reached?

Returns:

true if all the data has been read from the stream, else false

Since:

Servlet 3.1

isReady

public abstract boolean isReady()

Can data be read from this InputStream without blocking? Returns If this method is called and returns false, the container will invoke ReadListener.onDataAvailable() when data is available.

Returns:

true if data can be read without blocking, else false

Since:

Servlet 3.1

setReadListener

public abstract void setReadListener(ReadListener listener)

Sets the ReadListener for this ServletInputStream and thereby switches to non-blocking IO. It is only valid to switch to non-blocking IO within async processing or HTTP upgrade processing.

Parameters:

listener - The non-blocking IO read listener

Throws:

IllegalStateException - If this method is called if neither async nor HTTP upgrade is in progress or if the ReadListener has already been set

NullPointerException - If listener is null

Since:

Servlet 3.1