servlet过滤器解决乱码问题

  <filter>
     <filter-name>SetCharFilter</filter-name>
     <filter-class>com.filter.SetCharFilter</filter-class>
     <init-param>
        <param-name>ecoding</param-name>
        <param-value>utf-8</param-value>
     </init-param>
  </filter>
  <filter-mapping>
     <filter-name>SetCharFilter</filter-name>
     <url-pattern>/*</url-pattern>
  </filter-mapping>

package com.filter;

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;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class SetCharFilter implements Filter {
 private String encode = "";
    public void destroy()
    {