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org.apache.http.io
Class ChunkedOutputStream  

java.lang.Object
  java.io.OutputStream
      org.apache.http.io.ChunkedOutputStream

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public class ChunkedOutputStream

extends java.io.OutputStream

This class implements chunked transfer coding as described in the Section 3.6.1 of RFC 2616. Writes are buffered to an internal buffer (2048 default size). Chunks are guaranteed to be at least as large as the buffer size (except for the last chunk).

3.6.1 Chunked Transfer Coding

The chunked encoding modifies the body of a message in order to transfer it as a series of chunks, each with its own size indicator, followed by an OPTIONAL trailer containing entity-header fields. This allows dynamically produced content to be transferred along with the information necessary for the recipient to verify that it has received the full message.

  Chunked-Body   = *chunk
                   last-chunk
                   trailer
                   CRLF

  chunk          = chunk-size [ chunk-extension ] CRLF
                   chunk-data CRLF
  chunk-size     = 1*HEX
  last-chunk     = 1*("0") [ chunk-extension ] CRLF

  chunk-extension= *( ";" chunk-ext-name [ "=" chunk-ext-val ] )
  chunk-ext-name = token
  chunk-ext-val  = token | quoted-string
  chunk-data     = chunk-size(OCTET)
  trailer        = *(entity-header CRLF)
 

The chunk-size field is a string of hex digits indicating the size of the chunk. The chunked encoding is ended by any chunk whose size is zero, followed by the trailer, which is terminated by an empty line.

The trailer allows the sender to include additional HTTP header fields at the end of the message. The Trailer header field can be used to indicate which header fields are included in a trailer (see section 14.40).

A server using chunked transfer-coding in a response MUST NOT use the trailer for any header fields unless at least one of the following is true:

a)the request included a TE header field that indicates "trailers" is acceptable in the transfer-coding of the response, as described in section 14.39; or,

b)the server is the origin server for the response, the trailer fields consist entirely of optional metadata, and the recipient could use the message (in a manner acceptable to the origin server) without receiving this metadata. In other words, the origin server is willing to accept the possibility that the trailer fields might be silently discarded along the path to the client.

This requirement prevents an interoperability failure when the message is being received by an HTTP/1.1 (or later) proxy and forwarded to an HTTP/1.0 recipient. It avoids a situation where compliance with the protocol would have necessitated a possibly infinite buffer on the proxy.

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Field Summary
private  byte[]	cache
private  int	cachePosition
private  boolean	closed           True if the stream is closed.
private  HttpDataTransmitter	out
private  boolean	wroteLastChunk

 

Constructor Summary

ChunkedOutputStream(HttpDataTransmitter datatransmitter)           Wraps a data transmitter and chunks the output.

ChunkedOutputStream(HttpDataTransmitter out, int bufferSize)           Wraps a stream and chunks the output.

 

Method Summary
void	close()           Finishes writing to the underlying stream, but does NOT close the underlying stream.
void	finish()           Must be called to ensure the internal cache is flushed and the closing chunk is written.
void	flush()           Flushes the underlying stream, but leaves the internal buffer alone.
protected  void	flushCache()           Writes the cache out onto the underlying stream
protected  void	flushCacheWithAppend(byte[] bufferToAppend, int off, int len)           Writes the cache and bufferToAppend to the underlying stream as one large chunk
void	write(byte[] b)           Writes the array.
void	write(byte[] src, int off, int len)           This method writes len bytes from the specified array b starting at index off into the array.
void	write(int b)           This method writes a single byte to the output stream.
protected  void	writeClosingChunk()

 

Methods inherited from class java.lang.Object

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

 

Field Detail

out

private final HttpDataTransmitter out

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cache

private byte[] cache

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cachePosition

private int cachePosition

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wroteLastChunk

private boolean wroteLastChunk

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closed

private boolean closed

True if the stream is closed.

Constructor Detail

ChunkedOutputStream

public ChunkedOutputStream(HttpDataTransmitter out,
                           int bufferSize)
                    throws java.io.IOException

Wraps a stream and chunks the output.

Since:

3.0

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ChunkedOutputStream

public ChunkedOutputStream(HttpDataTransmitter datatransmitter)
                    throws java.io.IOException

Wraps a data transmitter and chunks the output. The default buffer size of 2048 was chosen because the chunk overhead is less than 0.5%

Method Detail

flushCache

protected void flushCache()
                   throws java.io.IOException

Writes the cache out onto the underlying stream

Since:

3.0

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flushCacheWithAppend

protected void flushCacheWithAppend(byte[] bufferToAppend,
                                    int off,
                                    int len)
                             throws java.io.IOException

Writes the cache and bufferToAppend to the underlying stream as one large chunk

Since:

3.0

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writeClosingChunk

protected void writeClosingChunk()
                          throws java.io.IOException

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finish

public void finish()
            throws java.io.IOException

Must be called to ensure the internal cache is flushed and the closing chunk is written.

Since:

3.0

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write

public void write(int b)
           throws java.io.IOException

Description copied from class: java.io.OutputStream

This method writes a single byte to the output stream. The byte written is the low eight bits of the int passed and a argument.

Subclasses must provide an implementation of this abstract method

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write

public void write(byte[] b)
           throws java.io.IOException

Writes the array. If the array does not fit within the buffer, it is not split, but rather written out as one large chunk.

Since:

3.0

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write

public void write(byte[] src,
                  int off,
                  int len)
           throws java.io.IOException

Description copied from class: java.io.OutputStream

This method writes len bytes from the specified array b starting at index off into the array.

This method in this class calls the single byte write() method in a loop until all bytes have been written. Subclasses should override this method if possible in order to provide a more efficent implementation.

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flush

public void flush()
           throws java.io.IOException

Flushes the underlying stream, but leaves the internal buffer alone.

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close

public void close()
           throws java.io.IOException

Finishes writing to the underlying stream, but does NOT close the underlying stream.

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