#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

*

• http://www.apache.org/licenses/LICENSE-2.0

*

• 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);
  }

}