// Copyright (c) 2003-2012, Jodd Team (jodd.org). All Rights Reserved.
package jodd.servlet.filter;
import jodd.JoddDefault;
import jodd.typeconverter.Convert;
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;
/**
* 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:
*
* <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.
*/
public class CharacterEncodingFilter implements Filter {
/**
* The default character encoding to set for requests that pass through
* this filter.
*/
protected String encoding;
/**
* The filter configuration object we are associated with. If this value
* is null, this filter instance is not currently configured.
*/
protected FilterConfig filterConfig;
/**
* Should a character encoding specified by the client be ignored?
*/
protected boolean ignore = true;
/**
* 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 servlet request we are processing
* @param response servlet response we are creating
* @param chain 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 encodingStr = selectEncoding(request);
if (encodingStr != null) {
request.setCharacterEncoding(encodingStr);
response.setCharacterEncoding(encodingStr);
}
}
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");
if (this.encoding == null) {
this.encoding = JoddDefault.encoding;
}
this.ignore = Convert.toBooleanValue(filterConfig.getInitParameter("ignore"), true);
}
/**
* 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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