javawebparts.filter
Class ParameterMungerFilter

java.lang.Object
  |
  +--javawebparts.filter.ParameterMungerFilter

All Implemented Interfaces:

javax.servlet.Filter

public class ParameterMungerFilter

extends java.lang.Object

implements javax.servlet.Filter

This filter can perform various operations on incoming parameters. It allows for including or excluding paths from filter functionality. It also allows for performing one or more defined operations on every parameter received.

Init parameters are:

• pathSpec - Either "include" or "exclude". This determines whether the list of paths in the pathList parameter is a list of paths to include in filter functionality, or a list of paths to exclude. Required: No. Default: None.



• pathList - This is a comma-separated list of paths, which can use asterisk for wildcard support, that denotes either paths to include or exclude from the functioning of this filter (depending on what pathSpec is set to). The paths ARE case-senitive! There is no limit to how many items can be specified, although for performance reasons a developer will probably want to specify as few as possible to get the job done (each requested path is matched via regex). Note also that you are of course still required to specify a path for the filter itself as per the servlet spec. This parameter however, together with pathSpec, gives you more control and flexibility than that setting alone. Required: No. Default: None.
  
  General note on pathSpec and pathList: If pathSpec is not specified but pathList IS, then 'exclude' is assumed for pathSpec. If pathSpec is specified by pathList IS NOT, then the filter WILL NEVER EXECUTE (this is technically a misconfiguration). If NEITHER is defined then the generic filter mapping will be in effect only.



• functionList - This is a comma-separated list of functions to perform on all parameters of the request. You can string as many of these functions together as you wish. The supported values are 'trim' (trim whitespace from both ends of the parameter), 'ucase' (convert parameter to upper-case), 'lcase' (conert the parameter to lower-case), 'reverse' (reverse the parameter, i.e., java becomes avaj). Required: Yes. Default: None (must be at least one of the valid values).

Example configuration in web.xml:

<filter>
<filter-name>ParameterMungerFilter</filter-name>
<filter-class>javawebparts.filter. ParameterMungerFilter</filter-class>
<init-param>
<param-name>pathSpec</param-name>
<param-value>include</param-value>
</init-param>
<init-param>
<param-name>pathList</param-name>
<param-value>*‍/parameterMungerFilterTest </param-value>
</init-param>
<init-param>
<param-name>functionList</param-name>
<param-value>trim,ucase,reverse</ param-value>
</init-param>
</filter>

<filter-mapping>
<filter-name>ParameterMungerFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>

Author:

Frank W. Zammetti.

Field Summary

private static java.lang.String	FUNCTION_LCASE Constant for function lcase function.
private static java.lang.String	FUNCTION_REVERSE Constant for function reverse function.
private static java.lang.String	FUNCTION_TRIM Constant for function trim function.
private static java.lang.String	FUNCTION_UCASE Constant for function ucase function.
private java.util.ArrayList	functionList The list of functions to be performed.
private static org.apache.commons.logging.Log	log Log instance.
private java.util.ArrayList	pathList List of paths for filter functionality determination.
private java.lang.String	pathSpec Whether pathList includes or excludes.

Constructor Summary

ParameterMungerFilter()

Method Summary

void	destroy() Destroy.
void	doFilter(javax.servlet.ServletRequest request, javax.servlet.ServletResponse response, javax.servlet.FilterChain filterChain) Do filter's work.
void	init(javax.servlet.FilterConfig filterConfig) Initialize this filter.

Methods inherited from class java.lang.Object

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

Field Detail

log

private static org.apache.commons.logging.Log log

Log instance.

FUNCTION_TRIM

private static final java.lang.String FUNCTION_TRIM

Constant for function trim function.

See Also:

Constant Field Values

FUNCTION_LCASE

private static final java.lang.String FUNCTION_LCASE

Constant for function lcase function.

See Also:

Constant Field Values

FUNCTION_UCASE

private static final java.lang.String FUNCTION_UCASE

Constant for function ucase function.

See Also:

Constant Field Values

FUNCTION_REVERSE

private static final java.lang.String FUNCTION_REVERSE

Constant for function reverse function.

See Also:

Constant Field Values

pathSpec

private java.lang.String pathSpec

Whether pathList includes or excludes.

pathList

private java.util.ArrayList pathList

List of paths for filter functionality determination.

functionList

private java.util.ArrayList functionList

The list of functions to be performed.

Constructor Detail

ParameterMungerFilter

public ParameterMungerFilter()

Method Detail

destroy

public void destroy()

Destroy.

Specified by:

destroy in interface javax.servlet.Filter

init

public void init(javax.servlet.FilterConfig filterConfig)
          throws javax.servlet.ServletException

Initialize this filter.

Specified by:

init in interface javax.servlet.Filter

Parameters:

filterConfig - The configuration information for this filter.

Throws:

javax.servlet.ServletException - ServletException.

doFilter

public void doFilter(javax.servlet.ServletRequest request,
                     javax.servlet.ServletResponse response,
                     javax.servlet.FilterChain filterChain)
              throws javax.servlet.ServletException,
                     java.io.IOException

Do filter's work.

Specified by:

doFilter in interface javax.servlet.Filter

Parameters:

request - The current request object.

response - The current response object.

filterChain - The current filter chain.

Throws:

javax.servlet.ServletException - ServletException.

java.io.IOException - IOException.