org.apache.http.conn
Class EofSensorInputStream

java.lang.Object
  java.io.InputStream
      org.apache.http.conn.EofSensorInputStream

All Implemented Interfaces:

Closeable, ConnectionReleaseTrigger

public class EofSensorInputStream
extends InputStream
implements ConnectionReleaseTrigger

A stream wrapper that triggers actions on close() and EOF. Primarily used to auto-release an underlying connection when the response body is consumed or no longer needed.

This class is based on AutoCloseInputStream in HttpClient 3.1, but has notable differences. It does not allow mark/reset, distinguishes different kinds of event, and does not always close the underlying stream on EOF. That decision is left to the watcher.

Since:

4.0

See Also:

EofSensorWatcher

Field Summary

protected InputStream

wrappedStream The wrapped input stream, while accessible.

Constructor Summary

EofSensorInputStream(InputStream in, EofSensorWatcher watcher)
Creates a new EOF sensor.

Method Summary

void	abortConnection() Aborts this stream.
int	available() Returns a int representing then number of bytes that are available before this InputStream will block.
protected void	checkAbort() Detects stream abort and notifies the watcher.
protected void	checkClose() Detects stream close and notifies the watcher.
protected void	checkEOF(int eof) Detects EOF and notifies the watcher.
void	close() Close the InputStream.
protected boolean	isReadAllowed() Checks whether the underlying stream can be read from.
int	read() Reads a single byte from this InputStream and returns the result as an int.
int	read(byte[] b) Reads bytes from the Stream and stores them in byte array b.
int	read(byte[] b, int off, int len) Reads at most length bytes from the Stream and stores them in byte array b starting at offset.
void	releaseConnection() Same as close().

Methods inherited from class java.io.InputStream

mark, markSupported, reset, skip

Methods inherited from class java.lang.Object

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

Field Detail

wrappedStream

protected InputStream wrappedStream

The wrapped input stream, while accessible. The value changes to null when the wrapped stream becomes inaccessible.

Constructor Detail

EofSensorInputStream

public EofSensorInputStream(InputStream in,
                            EofSensorWatcher watcher)

Creates a new EOF sensor. If no watcher is passed, the underlying stream will simply be closed when EOF is detected or close is called. Otherwise, the watcher decides whether the underlying stream should be closed before detaching from it.

Parameters:

in - the wrapped stream

watcher - the watcher for events, or null for auto-close behavior without notification

Method Detail

isReadAllowed

protected boolean isReadAllowed()
                         throws IOException

Checks whether the underlying stream can be read from.

Returns:

true if the underlying stream is accessible, false if this stream is in EOF mode and detached from the underlying stream

Throws:

IOException - if this stream is already closed

read

public int read()
         throws IOException

Description copied from class: InputStream

Reads a single byte from this InputStream and returns the result as an int. The low-order byte is returned or -1 of the end of stream was encountered. This abstract implementation must be provided by concrete subclasses.

Specified by:

read in class InputStream

Returns:

the byte read or -1 if end of stream.

Throws:

IOException - If the stream is already closed or another IOException occurs.

read

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

Description copied from class: InputStream

Reads at most length bytes from the Stream and stores them in byte array b starting at offset. Answer the number of bytes actually read or -1 if no bytes were read and end of stream was encountered.

Overrides:

read in class InputStream

Parameters:

b - the byte array in which to store the read bytes.

off - the offset in b to store the read bytes.

len - the maximum number of bytes to store in b.

Returns:

the number of bytes actually read or -1 if end of stream.

Throws:

IOException - If the stream is already closed or another IOException occurs.

read

public int read(byte[] b)
         throws IOException

Description copied from class: InputStream

Reads bytes from the Stream and stores them in byte array b. Answer the number of bytes actually read or -1 if no bytes were read and end of stream was encountered.

Overrides:

read in class InputStream

Parameters:

b - the byte array in which to store the read bytes.

Returns:

the number of bytes actually read or -1 if end of stream.

Throws:

IOException - If the stream is already closed or another IOException occurs.

available

public int available()
              throws IOException

Description copied from class: InputStream

Returns a int representing then number of bytes that are available before this InputStream will block. This method always returns 0. Subclasses should override and indicate the correct number of bytes available.

Overrides:

available in class InputStream

Returns:

the number of bytes available before blocking.

Throws:

IOException - If an error occurs in this InputStream.

close

public void close()
           throws IOException

Description copied from class: InputStream

Close the InputStream. Concrete implementations of this class should free any resources during close. This implementation does nothing.

Specified by:

close in interface Closeable

Overrides:

close in class InputStream

Throws:

IOException - If an error occurs attempting to close this InputStream.

checkEOF

protected void checkEOF(int eof)
                 throws IOException

Detects EOF and notifies the watcher. This method should only be called while the underlying stream is still accessible. Use isReadAllowed to check that condition.
If EOF is detected, the watcher will be notified and this stream is detached from the underlying stream. This prevents multiple notifications from this stream.

Parameters:

eof - the result of the calling read operation. A negative value indicates that EOF is reached.

Throws:

IOException - in case of an IO problem on closing the underlying stream

checkClose

protected void checkClose()
                   throws IOException

Detects stream close and notifies the watcher. There's not much to detect since this is called by close. The watcher will only be notified if this stream is closed for the first time and before EOF has been detected. This stream will be detached from the underlying stream to prevent multiple notifications to the watcher.

Throws:

IOException - in case of an IO problem on closing the underlying stream

checkAbort

protected void checkAbort()
                   throws IOException

Detects stream abort and notifies the watcher. There's not much to detect since this is called by abortConnection. The watcher will only be notified if this stream is aborted for the first time and before EOF has been detected or the stream has been closed gracefully. This stream will be detached from the underlying stream to prevent multiple notifications to the watcher.

Throws:

IOException - in case of an IO problem on closing the underlying stream

releaseConnection

public void releaseConnection()
                       throws IOException

Same as close().

Specified by:

releaseConnection in interface ConnectionReleaseTrigger

Throws:

IOException - in case of an IO problem. The connection will be released anyway.

abortConnection

public void abortConnection()
                     throws IOException

Aborts this stream. This is a special version of close() which prevents re-use of the underlying connection, if any. Calling this method indicates that there should be no attempt to read until the end of the stream.

Specified by:

abortConnection in interface ConnectionReleaseTrigger

Throws:

IOException - in case of an IO problem. The connection will be released anyway.