java代码：

import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class LoginServlet1 extends HttpServlet {    public void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        //request.setCharacterEncoding("utf-8");        String username = request.getParameter("username");        String passwrod = request.getParameter("passwrod");        //显示        response.getWriter().write("用户名 ："+username);        response.getWriter().write("密码："+passwrod);    }}

Filter代码

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 FilterDemo3 implements Filter {    private FilterConfig filterConfig;    public FilterDemo3()    {    }    public void init(FilterConfig filterConfig) throws ServletException {        this.filterConfig = filterConfig;    }    //Web容器调用    public void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {        String encoding = filterConfig.getInitParameter("encoding");        //POST请求编码设置        request.setCharacterEncoding(encoding);        //响应编码设置        response.setContentType("text/html;charset="+encoding);        chain.doFilter(request,response);    }    public void destroy() {    }}

login.jsp

HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">                                  <!--        -->        

web.xml

        FilterDemo3        cn.web.servlet.filter.FilterDemo3                   encoding           UTF-8                        FilterDemo3        /*