org.rakeshv.filters
Class CompressionResponseWrapper

java.lang.Object
  javax.servlet.ServletResponseWrapper
      javax.servlet.http.HttpServletResponseWrapper
          org.rakeshv.filters.CompressionResponseWrapper

All Implemented Interfaces:

javax.servlet.http.HttpServletResponse, javax.servlet.ServletResponse

public class CompressionResponseWrapper
extends javax.servlet.http.HttpServletResponseWrapper

A HttpServletResponseWrapper class that is used to create a compressed output stream. This class over-rides appropriate methods in the parent class to create compressed OutputStreams and PrintWriters.

Note: - It is REQUIRED that you set the value of the compressionType instance variable using the mutator method setCompressionType( int ) if the compression is to work.

© Copyright 2003, Rakesh Vidyadharan

Version:

$Id: CompressionResponseWrapper.java,v 1.5 2005/09/17 03:53:05 rakesh Exp $

Author:

Rakesh Vidyadharan 2^nd September 2003

Field Summary

protected int	compressionType An integer that indicates the type of compression that is to be used.
protected javax.servlet.http.HttpServletResponse	servletResponse Original response
protected javax.servlet.ServletOutputStream	stream The ServletOutputStream that has been returned by getOutputStream(), if any.
protected java.io.PrintWriter	writer The PrintWriter that has been returned by getWriter(), if any.

Fields inherited from interface javax.servlet.http.HttpServletResponse

SC_ACCEPTED, SC_BAD_GATEWAY, SC_BAD_REQUEST, SC_CONFLICT, SC_CONTINUE, SC_CREATED, SC_EXPECTATION_FAILED, SC_FORBIDDEN, SC_FOUND, SC_GATEWAY_TIMEOUT, SC_GONE, SC_HTTP_VERSION_NOT_SUPPORTED, SC_INTERNAL_SERVER_ERROR, SC_LENGTH_REQUIRED, SC_METHOD_NOT_ALLOWED, SC_MOVED_PERMANENTLY, SC_MOVED_TEMPORARILY, SC_MULTIPLE_CHOICES, SC_NO_CONTENT, SC_NON_AUTHORITATIVE_INFORMATION, SC_NOT_ACCEPTABLE, SC_NOT_FOUND, SC_NOT_IMPLEMENTED, SC_NOT_MODIFIED, SC_OK, SC_PARTIAL_CONTENT, SC_PAYMENT_REQUIRED, SC_PRECONDITION_FAILED, SC_PROXY_AUTHENTICATION_REQUIRED, SC_REQUEST_ENTITY_TOO_LARGE, SC_REQUEST_TIMEOUT, SC_REQUEST_URI_TOO_LONG, SC_REQUESTED_RANGE_NOT_SATISFIABLE, SC_RESET_CONTENT, SC_SEE_OTHER, SC_SERVICE_UNAVAILABLE, SC_SWITCHING_PROTOCOLS, SC_TEMPORARY_REDIRECT, SC_UNAUTHORIZED, SC_UNSUPPORTED_MEDIA_TYPE, SC_USE_PROXY

Constructor Summary

CompressionResponseWrapper(javax.servlet.http.HttpServletResponse response)
Constructs a compressed response adaptor wrapping the given response.

Method Summary

javax.servlet.ServletOutputStream	createOutputStream() Create a new instance of the CompressionResponseWrapper class, that compresses the response.
void	finish() Finishes writing compressed data to the CompressionResponseStream output stream without closing the underlying stream.
void	flushBuffer() Forces any content in the buffer to be written to the client.
int	getCompressionType() Returns compressionType.
javax.servlet.ServletOutputStream	getOutputStream() Returns a ServletOutputStream suitable for writing binary data in the response.
java.io.PrintWriter	getWriter() Returns a PrintWriter object that can send character text to the client.
void	setCompressionType(int compressionType) Set compressionType.

Methods inherited from class javax.servlet.http.HttpServletResponseWrapper

addCookie, addDateHeader, addHeader, addIntHeader, containsHeader, encodeRedirectUrl, encodeRedirectURL, encodeUrl, encodeURL, sendError, sendError, sendRedirect, setDateHeader, setHeader, setIntHeader, setStatus, setStatus

Methods inherited from class javax.servlet.ServletResponseWrapper

getBufferSize, getCharacterEncoding, getContentType, getLocale, getResponse, isCommitted, reset, resetBuffer, setBufferSize, setCharacterEncoding, setContentLength, setContentType, setLocale, setResponse

Methods inherited from class java.lang.Object

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

Methods inherited from interface javax.servlet.ServletResponse

getBufferSize, getCharacterEncoding, getContentType, getLocale, isCommitted, reset, resetBuffer, setBufferSize, setCharacterEncoding, setContentLength, setContentType, setLocale

Field Detail

servletResponse

protected javax.servlet.http.HttpServletResponse servletResponse

Original response

stream

protected javax.servlet.ServletOutputStream stream

The ServletOutputStream that has been returned by getOutputStream(), if any.

writer

protected java.io.PrintWriter writer

The PrintWriter that has been returned by getWriter(), if any.

compressionType

protected int compressionType

An integer that indicates the type of compression that is to be used. The different compression algorithms supported are the ones supported in the java.util.zip package.

Constructor Detail

CompressionResponseWrapper

public CompressionResponseWrapper(javax.servlet.http.HttpServletResponse response)
                           throws java.lang.IllegalArgumentException

Constructs a compressed response adaptor wrapping the given response. Calls the super-class constructor, and set the servletResponse reference.

Parameters:

response - - The response that is to be compressed.

Throws:

java.lang.IllegalArgumentException - - If the specified response is null.

Method Detail

createOutputStream

public javax.servlet.ServletOutputStream createOutputStream()
                                                     throws java.io.IOException

Create a new instance of the CompressionResponseWrapper class, that compresses the response.

Returns:

ServletOutputStream - The appropriate instance of the ServletOutputStream that wraps a DeflaterOutputStream .

Throws:

java.io.IOException - - If exceptions are encountered while creating the compressed response stream.

flushBuffer

public void flushBuffer()
                 throws java.io.IOException

Forces any content in the buffer to be written to the client. A call to this method automatically commits the response, meaning the status code and headers will be written.

Specified by:

flushBuffer in interface javax.servlet.ServletResponse

Overrides:

flushBuffer in class javax.servlet.ServletResponseWrapper

Throws:

java.io.IOException

getOutputStream

public javax.servlet.ServletOutputStream getOutputStream()
                                                  throws java.io.IOException

Returns a ServletOutputStream suitable for writing binary data in the response. If a Writer has not already been created for the response (through a call to getWriter() method) a new instance of the CompressionResponseStream is created, and the instance variable stream set to the new instance created. If the stream has already been initialised, then the reference is returned.

Specified by:

getOutputStream in interface javax.servlet.ServletResponse

Overrides:

getOutputStream in class javax.servlet.ServletResponseWrapper

Throws:

java.io.IOException - - If errors are encountered while creating the compressed response stream.

java.lang.IllegalStateException - - If getWriter() has already been called on this instance.

getWriter

public java.io.PrintWriter getWriter()
                              throws java.io.IOException

Returns a PrintWriter object that can send character text to the client. The PrintWriter is created on top of the appropriate CompressionResponseStream class. The character encoding used is the one specified in the charset= property of the setContentType( java.lang.String ) method, which must be called before calling this method for the charset to take effect.

If necessary, the MIME type of the response is modified to reflect the character encoding used.

Either this method or getOutputStream() may be called to write the body, not both.

Specified by:

getWriter in interface javax.servlet.ServletResponse

Overrides:

getWriter in class javax.servlet.ServletResponseWrapper

Throws:

java.io.IOException - - If errors are encountered while creating the compressed response stream.

java.lang.IllegalStateException - - If getWriter() has already been called on this instance.

finish

public void finish()
            throws java.io.IOException

Finishes writing compressed data to the CompressionResponseStream output stream without closing the underlying stream.

Note: This method must be invoked by to properly finish the output if multiple filters are added in succession to the same output stream. This is generally the case, and hence this method must be called in order for the response to be completely sent back to the client.

Throws:

java.io.IOException - - If errors are encountered while writing to the stream. An exception will be thrown if this method is invoked after the stream has been closed.

getCompressionType

public final int getCompressionType()

Returns compressionType.

Returns:

int - The value/reference of/to compressionType.

setCompressionType

public final void setCompressionType(int compressionType)

Set compressionType.

Parameters:

compressionType - - The value to set.