Filter拦截器处理字符集问题

package com.wenq.www.filter;

import java.io.IOException;
import java.util.Date;

import javax.servlet.*;

public class TestFilter implements Filter {
   
    FilterConfig config;
    String encoding;

    public void destroy() {
       
    }

    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {
        if(encoding!=null&&!encoding.equals("")){
            request.setCharacterEncoding(encoding);
            System.out.println("编码为:"+encoding);
        }
        else {
            request.setCharacterEncoding("GBK");
        }
        chain.doFilter(request, response);
    }

    public void init(FilterConfig config) throws ServletException {
        this.config = config;
        this.encoding=config.getInitParameter("encoding");
        System.out.println("insert encoding:"+encoding);
    }

}

web.xml

配置文件：

<filter>
    <filter-name>fristFilter</filter-name>
    <filter-class>com.wenq.www.filter.TestFilter</filter-class>
    <init-param>
    <param-name>encoding</param-name>
    <param-value>UTF-8</param-value>
    </init-param>
</filter>

<filter-mapping>
    <filter-name>fristFilter</filter-name>
    <servlet-name>/*</servlet-name>
</filter-mapping>