package com.demo.test;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 characterEncodingFilter implements Filter {        private String characterEncoding;    private boolean enabled;    public void destroy() {        // TODO Auto-generated method stub        characterEncoding = null;//销毁时清空资源    }    public void doFilter(ServletRequest request, ServletResponse response,            FilterChain chain) throws IOException, ServletException {        // TODO Auto-generated method stub        if(enabled || characterEncoding != null){
   //如果启用该Filter            request.setCharacterEncoding(characterEncoding);//设置reques编码            response.setCharacterEncoding(characterEncoding);//设置response编码        }        chain.doFilter(request,response );//doFilter,执行下一个Filter或者Servlet    }    public void init(FilterConfig config) throws ServletException {
   //初始化时加载参数        // TODO Auto-generated method stub        characterEncoding = config.getInitParameter(characterEncoding);//编码方式        enabled = "true".equalsIgnoreCase(config.getInitParameter("enabled").trim());//启用    }  }

characterEncoding表示编码方式，enabled表示是否启用编码，分别从初始化参数中取值。

web.xml中的配置如下：

     
       
            
          
       
        index.jsp
         
        
          
       
        characterEncodingFilter
           
       
        com.helloweenvsfei.filter.CharacterEncodingFilter
           
             
        
         characterEncoding
              
        
         UTF-8
            
           
             
        
         enabled
              
        
         true
            
         
        
          
       
        characterEncodingFilter
           
       
        /*
         
      
     

如果使用的字符编码Filter、request中取出的字符可能是乱码，否则不会出乱码。页面编码的方式与Filter编码方式必须一致。另外，如果表单是GET方式提交的，还需要修改Tomcat的conf/servlet.xml配置文件，制定URIEncoding(默认为IOS-8859-1);否则，依然会出现乱码。修改如下：

<Connector port="8080" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" URIEncoding="UTF-8">