nl.b3p.web.filter

Class SetCharacterEncodingFilter

java.lang.Object

nl.b3p.web.filter.SetCharacterEncodingFilter

All Implemented Interfaces:

javax.servlet.Filter

public class SetCharacterEncodingFilter
extends Object
implements javax.servlet.Filter

Example filter that sets the character encoding to be used in parsing the incoming request, either unconditionally or only if the client did not specify a character encoding. Configuration of this filter is based on the following initialization parameters:

• encoding - The character encoding to be configured for this request, either conditionally or unconditionally based on the ignore initialization parameter. This parameter is required, so there is no default.
• ignore - If set to "true", any character encoding specified by the client is ignored, and the value returned by the selectEncoding() method is set. If set to "false, selectEncoding() is called only if the client has not already specified an encoding. By default, this parameter is set to "true".

Although this filter can be used unchanged, it is also easy to subclass it and make the selectEncoding() method more intelligent about what encoding to choose, based on characteristics of the incoming request (such as the values of the Accept-Language and User-Agent headers, or a value stashed in the current user's session.

Version:

$Id$

Author:

Craig McClanahan

Field Summary

Fields

Modifier and Type	Field and Description
protected String	encoding The default character encoding to set for requests that pass through this filter.
protected javax.servlet.FilterConfig	filterConfig The filter configuration object we are associated with.
protected boolean	ignore Should a character encoding specified by the client be ignored?

Constructor Summary

Constructors

Constructor and Description
SetCharacterEncodingFilter()

Method Summary

Modifier and Type	Method and Description
void	destroy() Take this filter out of service.
void	doFilter(javax.servlet.ServletRequest request, javax.servlet.ServletResponse response, javax.servlet.FilterChain chain) Select and set (if specified) the character encoding to be used to interpret request parameters for this request.
void	init(javax.servlet.FilterConfig filterConfig) Place this filter into service.
protected String	selectEncoding(javax.servlet.ServletRequest request) Select an appropriate character encoding to be used, based on the characteristics of the current request and/or filter initialization parameters.

Methods inherited from class java.lang.Object

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

Field Detail

encoding

protected String encoding

The default character encoding to set for requests that pass through this filter.

filterConfig

protected javax.servlet.FilterConfig filterConfig

The filter configuration object we are associated with. If this value is null, this filter instance is not currently configured.

ignore

protected boolean ignore

Should a character encoding specified by the client be ignored?

Constructor Detail

SetCharacterEncodingFilter

public SetCharacterEncodingFilter()

Method Detail

destroy

public void destroy()

Take this filter out of service.

Specified by:

destroy in interface javax.servlet.Filter

doFilter

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

Select and set (if specified) the character encoding to be used to interpret request parameters for this request.

Specified by:

doFilter in interface javax.servlet.Filter

Parameters:

request - The servlet request we are processing

response - The servlet response we are creating

chain - The filter chain we are processing

Throws:

IOException - if an input/output error occurs

javax.servlet.ServletException - if a servlet error occurs

init

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

Place this filter into service.

Specified by:

init in interface javax.servlet.Filter

Parameters:

filterConfig - The filter configuration object

Throws:

javax.servlet.ServletException

selectEncoding

protected String selectEncoding(javax.servlet.ServletRequest request)

Select an appropriate character encoding to be used, based on the characteristics of the current request and/or filter initialization parameters. If no character encoding should be set, return null.

The default implementation unconditionally returns the value configured by the encoding initialization parameter for this filter.

Parameters:

request - The servlet request we are processing

Returns:

the encoding of the request