Package com.twelvemonkeys.servlet.image

Class ImageFilter

java.lang.Object

com.twelvemonkeys.servlet.GenericFilter

com.twelvemonkeys.servlet.image.ImageFilter

All Implemented Interfaces:

java.io.Serializable, javax.servlet.Filter, javax.servlet.FilterConfig

Direct Known Subclasses:

AWTImageFilterAdapter, BufferedImageOpAdapter, ComposeFilter, ContentNegotiationFilter, NullImageFilter, RotateFilter, ScaleFilter, SourceRenderFilter

public abstract class ImageFilter
extends GenericFilter

Abstract base class for image filters. Automatically decoding and encoding of the image is handled in the doFilterImpl method.

Version:

$Id: ImageFilter.java#2 $

Author:

Harald Kuhr

See Also:

doFilter(java.awt.image.BufferedImage,javax.servlet.ServletRequest,ImageServletResponse), Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
protected java.lang.String[]	triggerParams

Fields inherited from class com.twelvemonkeys.servlet.GenericFilter

oncePerRequest

Constructor Summary

Constructors

Constructor	Description
ImageFilter()

Method Summary

Modifier and Type	Method	Description
protected abstract java.awt.image.RenderedImage	doFilter(java.awt.image.BufferedImage pImage, javax.servlet.ServletRequest pRequest, ImageServletResponse pResponse)	Filters the image for this request.
protected void	doFilterImpl(javax.servlet.ServletRequest pRequest, javax.servlet.ServletResponse pResponse, javax.servlet.FilterChain pChain)	The doFilterImpl method is called once, or each time a request/response pair is passed through the chain, depending on the GenericFilter.oncePerRequest member variable.
void	setTriggerParams(java.lang.String pTriggerParams)	Sets the trigger parameters.
protected boolean	trigger(javax.servlet.ServletRequest pRequest)	Tests if the filter should do image filtering/processing.

Methods inherited from class com.twelvemonkeys.servlet.GenericFilter

destroy, doFilter, getFilterConfig, getFilterName, getInitParameter, getInitParameterNames, getServletContext, init, init, log, log, setFilterConfig, setOncePerRequest

Methods inherited from class java.lang.Object

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

Field Detail

triggerParams

protected java.lang.String[] triggerParams

Constructor Detail

ImageFilter

public ImageFilter()

Method Detail

doFilterImpl

protected void doFilterImpl(javax.servlet.ServletRequest pRequest,
                            javax.servlet.ServletResponse pResponse,
                            javax.servlet.FilterChain pChain)
                     throws java.io.IOException,
                            javax.servlet.ServletException

The doFilterImpl method is called once, or each time a request/response pair is passed through the chain, depending on the GenericFilter.oncePerRequest member variable.

Specified by:

doFilterImpl in class GenericFilter

Parameters:

pRequest - the servlet request

pResponse - the servlet response

pChain - the filter chain

Throws:

java.io.IOException

javax.servlet.ServletException

See Also:

GenericFilter.oncePerRequest, doFilter, Filter.doFilter

trigger

protected boolean trigger(javax.servlet.ServletRequest pRequest)

Tests if the filter should do image filtering/processing.

This default implementation uses triggerParams to test if:

mTriggerParams == null

return true

mTriggerParams != null, loop through parameters, and test if pRequest contains the parameter. If match

return true

Otherwise

return false

Parameters:

pRequest - the servlet request

Returns:

true if the filter should do image filtering

setTriggerParams

public void setTriggerParams(java.lang.String pTriggerParams)

Sets the trigger parameters. The parameter is supposed to be a comma-separated string of parameter names.

Parameters:

pTriggerParams - a comma-separated string of parameter names.

doFilter

protected abstract java.awt.image.RenderedImage doFilter(java.awt.image.BufferedImage pImage,
                                                         javax.servlet.ServletRequest pRequest,
                                                         ImageServletResponse pResponse)
                                                  throws java.io.IOException

Filters the image for this request.

Parameters:

pImage - the image to filter

pRequest - the servlet request

pResponse - the servlet response

Returns:

the filtered image

Throws:

java.io.IOException - if an I/O error occurs during filtering