登录成功界面和失败界面就不发了，很简单

登录界面login.jsp

  







<!--
    
    -->
    
登录界面
    


        账号:

        密码:

            
        

    
  

Web.xml文件

LoginFiltercom.imooc.filter.LoginFilterkeywordslogin.jsp;failure.jsp;LoginServlet;LoginFilter/*REQUESTThis is the description of my J2EE componentThis is the display name of my J2EE componentLoginServletcom.imooc.servlet.LoginServletLoginServlet/servlet/LoginServletindex.jspBASIC

LoginServlet
(简单处理)

package com.imooc.servlet;
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 LoginServlet extends HttpServlet {
    public LoginServlet() {
        super();
    }

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        response.setContentType("text/html;charset=utf-8");
        PrintWriter out = response.getWriter();

        out.close();
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        response.setContentType("text/html;charset=utf-8");
        PrintWriter out = response.getWriter();

        String username = request.getParameter("username");
        String password = request.getParameter("password");
        request.getSession().setAttribute("username", username);
        if ("admit".equals(username) && "admit".equals(password)) {
            response.sendRedirect("../success.jsp");
        } else {
            response.sendRedirect("../failure.jsp");
        }
        out.close();
    }
}

过滤器LoginFilter

package com.imooc.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 LoginFilter implements Filter {

    private FilterConfig config;

    public void destroy() {
        // TODO Auto-generated method stub

    }

    public void doFilter(ServletRequest arg0, ServletResponse arg1,
            FilterChain arg2) throws IOException, ServletException {
        HttpServletRequest request=(HttpServletRequest) arg0;
        HttpServletResponse response= (HttpServletResponse) arg1;

        String init=config.getInitParameter("keywords");
        String[] words=init.split(";");
        for (String str : words) {
            if(request.getRequestURI().indexOf(str)!=-1){
                arg2.doFilter(arg0, arg1);
                return;
            }
        }

        String username=(String) request.getSession().getAttribute("username");
        if(username!=null&&!(username.equals(""))){
            arg2.doFilter(arg0, arg1);
        }
        else{
            response.sendRedirect("login.jsp");
        }

    }

    public void init(FilterConfig arg0) throws ServletException {
        config=arg0;

    }
}