setcharacterencodingfilter.java

这是我们做的一个网上购物系统,包手用户和管理员两大功能模块,采用jsp+servlet+java bean技术.

package com.qyg.tools;

import javax.servlet.ServletRequest;

//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;
//
//public class SetCharacterEncodingFilter implements Filter {
//	protected FilterConfig filterConfig;
//	protected String encodeingName;
//	protected boolean enable;
//	
//	public SetCharacterEncodingFilter(){
//		this.encodeingName = "gbk";
//		this.enable = false;
//	}
//	
//	public void init(FilterConfig filterConfig)throws ServletException{
//		 this.filterConfig = filterConfig;
//		 loadConfigParams();
//	}
//	
//	private void loadConfigParams(){
//		this.encodeingName = this.filterConfig.getInitParameter("encoding");
//		String strIgnoreFlag = this.filterConfig.getInitParameter("enable");
//		
//		if(strIgnoreFlag.equals("true")){
//			this.enable = true;
//		}else{
//			this.enable = false;
//		}
//	}
//	
//	public void doFilter(ServletRequest request , ServletResponse response , FilterChain chain)
//	throws IOException , ServletException{
//		if(this.enable){
//			request.setCharacterEncoding(this.encodeingName);
//		}
//		chain.doFilter(request, response);
//	}
//	
//	public void destroy(){}
//}

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: 500674 $ $Date: 2007-01-28 00:15:00 +0100 (dim., 28 janv. 2007) $
*/

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("enable");
      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);

  }
}