#FORMAT Java
/*
- Copyright 2004 The Apache Software Foundation
*
- Licensed under the Apache License, Version 2.0 (the "License");
- you may not use this file except in compliance with the License.
- You may obtain a copy of the License at
*
*
- Unless required by applicable law or agreed to in writing, software
- distributed under the License is distributed on an "AS IS" BASIS,
- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- See the License for the specific language governing permissions and
- limitations under the License.
*/
package org.apache.servlet;
import java.io.IOException;
import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.FilterConfig; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse;
/**
- <p>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:</p>
- <ul>
- <li><strong>encoding</strong> - The character encoding to be configured
- for this request, either conditionally or unconditionally based on
- the <code>ignore</code> initialization parameter. This parameter
- is required, so there is no default.</li>
- <li><strong>ignore</strong> - If set to "true", any character encoding
- specified by the client is ignored, and the value returned by the
- <code>selectEncoding()</code> method is set. If set to "false,
- <code>selectEncoding()</code> is called <strong>only</strong> if the
- client has not already specified an encoding. By default, this
- parameter is set to "true".</li>
- </ul> *
- <p>Although this filter can be used unchanged, it is also easy to
- subclass it and make the <code>selectEncoding()</code> method more
- intelligent about what encoding to choose, based on characteristics of
- the incoming request (such as the values of the <code>Accept-Language</code>
- and <code>User-Agent</code> headers, or a value stashed in the current
- user's session.</p> *
- @author Craig McClanahan
- @version $Revision: 267129 $ $Date: 2004-03-18 11:40:35 -0500 (Thu, 18 Mar 2004) $ */
public class SetCharacterEncodingFilter implements Filter {
// ---- Instance Variables
/**
- The default character encoding to set for requests that pass through
- this filter. */
protected String encoding = null;
/** - The filter configuration object we are associated with. If this value
- is null, this filter instance is not currently configured. */
protected FilterConfig filterConfig = null;
/** - Should a character encoding specified by the client be ignored? */
protected boolean ignore = true;
// ---- Public Methods
/** - Take this filter out of service. */
public void destroy() {
this.encoding = null;
this.filterConfig = null;
}
/** - Select and set (if specified) the character encoding to be used to
- interpret request parameters for this request. *
- @param request The servlet request we are processing
- @param result The servlet response we are creating
- @param chain The filter chain we are processing *
- @exception IOException if an input/output error occurs
- @exception ServletException if a servlet error occurs */
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain)
throws IOException, ServletException {
// Conditionally select and set the character encoding to be used
if (ignore | (request.getCharacterEncoding() == null)) {
String encoding = selectEncoding(request);
if (encoding != null)
request.setCharacterEncoding(encoding);
}
// Pass control on to the next filter
chain.doFilter(request, response);
}
/** - Place this filter into service. *
- @param filterConfig The filter configuration object */
public void init(FilterConfig filterConfig) throws ServletException {
this.filterConfig = filterConfig;
this.encoding = filterConfig.getInitParameter("encoding");
String value = filterConfig.getInitParameter("ignore");
if (value == null)
this.ignore = true;
else if (value.equalsIgnoreCase("true"))
this.ignore = true;
else if (value.equalsIgnoreCase("yes"))
this.ignore = true;
else
this.ignore = false;
}
// ---- Protected Methods
/** - 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
- <code>null</code>.
- <p>
- The default implementation unconditionally returns the value configured
- by the <strong>encoding</strong> initialization parameter for this
- filter. *
- @param request The servlet request we are processing */
protected String selectEncoding(ServletRequest request) {
return (this.encoding);
}
}