#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);
    }

}

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