java如何创建过滤器

弄过滤器，要实现filter接口，下面我写一个小例子
主要是用过滤器处理中文编码，至于你要用来做什么，你再自己写。。。比如权限控制，登录验证，之类

//下面这是一个类。。。。
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 doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
request.setCharacterEncoding("GBK");//处理编码
response.setCharacterEncoding("GBK");//处理编码

chain.doFilter(request, response);//让过滤器执行下一个请求
}

public void destroy() {}

public void init(FilterConfig arg0) throws ServletException {}
}<