setcharacterencodingfilter.java

学生信息管理系统 jsp + sql + javabean 实现

package sms.filter;

import javax.servlet.*;
import java.io.IOException;
public class SetCharacterEncodingFilter implements Filter  {

 //-----------------instance variables
 /**
  * The default character encoding to set for request 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;
 /**
  * Take this filter out of service
  */
 public void destroy(){
 this.encoding =null;
 this.filterConfig =null;
 }
 /**
  *
  * @param request ServletRequest
  * @param response ServletResponse
  * @param chain FilterChain
  * @throws IOException
  * @throws ServletException
  */
 public void doFilter(ServletRequest request,ServletResponse response,FilterChain chain)
 throws IOException,ServletException{
   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
  */
 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 String selectEncoding(ServletRequest request){
   return(this.encoding );
 }
 }