org.apache.http.io
Class ChunkedInputStream

java.lang.Object
  extended by java.io.InputStream
      extended by org.apache.http.io.ChunkedInputStream
All Implemented Interfaces:
java.io.Closeable

public class ChunkedInputStream
extends java.io.InputStream

This class implements chunked transfer coding as described in the Section 3.6.1 of RFC 2616. It transparently coalesces chunks of a HTTP stream that uses chunked transfer coding.

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.

Note that this class NEVER closes the underlying stream, even when close gets called. Instead, it will read until the "end" of its chunking on close, which allows for the seamless invocation of subsequent HTTP 1.1 calls, while not requiring the client to remember to read the entire contents of the response.

Since:
2.0
Author:
Ortwin Glueck, Sean C. Sullivan, Martin Elwin, Eric Johnson, Mike Bowler, Michael Becke, Oleg Kalnichevski

Constructor Summary
ChunkedInputStream(HttpDataReceiver in)
           
 
Method Summary
 void close()
          Upon close, this reads the remainder of the chunked message, leaving the underlying socket at a position to start reading the next response without scanning.
(package private) static void exhaustInputStream(java.io.InputStream inStream)
          Exhaust an input stream, reading until EOF has been encountered.
 Header[] getFooters()
           
 int read()
           Returns all the data in a chunked stream in coalesced form.
 int read(byte[] b)
          Read some bytes from the stream.
 int read(byte[] b, int off, int len)
          Read some bytes from the stream.
 
Methods inherited from class java.io.InputStream
available, mark, markSupported, reset, skip
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

ChunkedInputStream

public ChunkedInputStream(HttpDataReceiver in)
Method Detail

read

public int read()
         throws java.io.IOException

Returns all the data in a chunked stream in coalesced form. A chunk is followed by a CRLF. The method returns -1 as soon as a chunksize of 0 is detected.

Trailer headers are read automcatically at the end of the stream and can be obtained with the getResponseFooters() method.

Specified by:
read in class java.io.InputStream
Returns:
-1 of the end of the stream has been reached or the next data byte
Throws:
java.io.IOException - If an IO problem occurs

read

public int read(byte[] b,
                int off,
                int len)
         throws java.io.IOException
Read some bytes from the stream.

Overrides:
read in class java.io.InputStream
Parameters:
b - The byte array that will hold the contents from the stream.
off - The offset into the byte array at which bytes will start to be placed.
len - the maximum number of bytes that can be returned.
Returns:
The number of bytes returned or -1 if the end of stream has been reached.
Throws:
java.io.IOException - if an IO problem occurs.
See Also:
InputStream.read(byte[], int, int)

read

public int read(byte[] b)
         throws java.io.IOException
Read some bytes from the stream.

Overrides:
read in class java.io.InputStream
Parameters:
b - The byte array that will hold the contents from the stream.
Returns:
The number of bytes returned or -1 if the end of stream has been reached.
Throws:
java.io.IOException - if an IO problem occurs.
See Also:
InputStream.read(byte[])

close

public void close()
           throws java.io.IOException
Upon close, this reads the remainder of the chunked message, leaving the underlying socket at a position to start reading the next response without scanning.

Specified by:
close in interface java.io.Closeable
Overrides:
close in class java.io.InputStream
Throws:
java.io.IOException - If an IO problem occurs.

getFooters

public Header[] getFooters()

exhaustInputStream

static void exhaustInputStream(java.io.InputStream inStream)
                        throws java.io.IOException
Exhaust an input stream, reading until EOF has been encountered.

Note that this function is intended as a non-public utility. This is a little weird, but it seemed silly to make a utility class for this one function, so instead it is just static and shared that way.

Parameters:
inStream - The InputStream to exhaust.
Throws:
java.io.IOException - If an IO problem occurs


Copyright 2005-2005-2006 Apache Software Foundation. All Rights Reserved.