org.rakeshv.filters
Class CachingResponseWrapper

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

All Implemented Interfaces:

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

public class CachingResponseWrapper
extends javax.servlet.http.HttpServletResponseWrapper

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

© Copyright 2005, Rakesh Vidyadharan

Version:

$Id: CachingResponseWrapper.java,v 1.4 2005/10/16 02:19:57 rakesh Exp $

Author:

Rakesh Vidyadharan 15^th September 2005

Field Summary

protected java.io.File	cacheFile The file to which the cached contents are to be written.
private CachingFilter.FileProperties	fileProperties The CachingFilter.FileProperties that is to be modified if the content properties for the response are modified by objects down the filter chain.
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

CachingResponseWrapper(javax.servlet.http.HttpServletResponse response, java.io.File file, CachingFilter.FileProperties fileProperties)
Constructs a cached response adaptor wrapping the given response.

Method Summary

void	addHeader(java.lang.String name, java.lang.String value) Add the specified header to the fileProperties
void	closeCacheFile() Closes the cached file in the CachingResponseStream without closing the underlying stream.
javax.servlet.ServletOutputStream	createOutputStream() Create a new instance of the CachingResponseWrapper class, that compresses the response.
void	flushBuffer() Forces any content in the buffer to be written to the client.
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	setCharacterEncoding(java.lang.String charset) Update the property in the fileProperties and then pass along to the super class implementation.
void	setContentType(java.lang.String type) Update the property in the fileProperties and then pass along to the super class implementation.
void	setHeader(java.lang.String name, java.lang.String value) Add the specified header to the fileProperties
void	setLocale(java.util.Locale locale) Update the property in the fileProperties and then pass along to the super class implementation.
void	setStatus(int status) If the status is not equal to SC_OK, indicate to the fileProperties that the response should not be cached.

Methods inherited from class javax.servlet.http.HttpServletResponseWrapper

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

Methods inherited from class javax.servlet.ServletResponseWrapper

getBufferSize, getCharacterEncoding, getContentType, getLocale, getResponse, isCommitted, reset, resetBuffer, setBufferSize, setContentLength, 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, setContentLength

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.

cacheFile

protected java.io.File cacheFile

The file to which the cached contents are to be written.

fileProperties

private CachingFilter.FileProperties fileProperties

The CachingFilter.FileProperties that is to be modified if the content properties for the response are modified by objects down the filter chain.

Constructor Detail

CachingResponseWrapper

public CachingResponseWrapper(javax.servlet.http.HttpServletResponse response,
                              java.io.File file,
                              CachingFilter.FileProperties fileProperties)
                       throws java.lang.IllegalArgumentException

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

Parameters:

response - The response that is to be cached.

file - The file to which the contents are to be cached.

fileProperties - The FileProperties that will be passed along to the CachingResponseStream.

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 CachingResponseWrapper 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 cached 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 CachingResponseStream 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 cached 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 CachingResponseStream 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 cached response stream.

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

closeCacheFile

public void closeCacheFile()
                    throws java.io.IOException

Closes the cached file in the CachingResponseStream without closing the underlying stream.

Note: This method must be invoked by to ensure that the cache file that was generated is properly closed after the actual response was generated.

Throws:

java.io.IOException - - If errors are encountered while closing the file.

addHeader

public void addHeader(java.lang.String name,
                      java.lang.String value)

Add the specified header to the fileProperties

Specified by:

addHeader in interface javax.servlet.http.HttpServletResponse

Overrides:

addHeader in class javax.servlet.http.HttpServletResponseWrapper

Parameters:

name - The name of the header

value - The value of the header

setHeader

public void setHeader(java.lang.String name,
                      java.lang.String value)

Add the specified header to the fileProperties

Specified by:

setHeader in interface javax.servlet.http.HttpServletResponse

Overrides:

setHeader in class javax.servlet.http.HttpServletResponseWrapper

Parameters:

name - The name of the header

value - The value of the header

setCharacterEncoding

public void setCharacterEncoding(java.lang.String charset)

Update the property in the fileProperties and then pass along to the super class implementation.

Specified by:

setCharacterEncoding in interface javax.servlet.ServletResponse

Overrides:

setCharacterEncoding in class javax.servlet.ServletResponseWrapper

Parameters:

charset - A String specifying only the character set defined by IANA Character Sets (http://www.iana.org/assignments/character-sets)

setContentType

public void setContentType(java.lang.String type)

Update the property in the fileProperties and then pass along to the super class implementation.

Specified by:

setContentType in interface javax.servlet.ServletResponse

Overrides:

setContentType in class javax.servlet.ServletResponseWrapper

Parameters:

type - A String specifying the MIME type of the content

setLocale

public void setLocale(java.util.Locale locale)

Update the property in the fileProperties and then pass along to the super class implementation.

Specified by:

setLocale in interface javax.servlet.ServletResponse

Overrides:

setLocale in class javax.servlet.ServletResponseWrapper

Parameters:

locale - The locale of the response

setStatus

public void setStatus(int status)

If the status is not equal to SC_OK, indicate to the fileProperties that the response should not be cached.

Specified by:

setStatus in interface javax.servlet.http.HttpServletResponse

Overrides:

setStatus in class javax.servlet.http.HttpServletResponseWrapper

Parameters:

status - The status code to set for the response.