filter的写法

package com.insigma.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 EncodingFilter implements Filter {
    public void destroy() {
    }

    public void doFilter(ServletRequest req, ServletResponse resp,
            FilterChain chain) throws IOException, ServletException {
           HttpServletRequest request = (HttpServletRequest) req;
           HttpServletResponse response = (HttpServletResponse) resp;
           request.setCharacterEncoding("utf-8");
           response.setCharacterEncoding("utf-8");
          chain.doFilter(req, resp);
    }

    public void init(FilterConfig arg0) throws ServletException {
    }

}