index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> </head> <body> <h1>我的網站</h1><hr> <% //獲取session中的登錄狀態 String user = (String)session.getAttribute("user");//這里的 user是session的標記 %> <% if(user == null || "".equals(user)){//用戶沒有登錄 %> 歡迎光臨!游客! <a href="${pageContext.request.contextPath }/loginout/login.jsp">登錄</a> <a href="#">注冊</a> <% }else{//用戶登錄過 %> 歡迎回來!<%=user %>! <a href="${pageContext.request.contextPath }/servlet/LogoutServlet">注銷</a> <% } %> </body> </html>
login.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> </head> <body> <h1>我的網站-登錄</h1><hr> <form action="${pageContext.request.contextPath }/servlet/LoginServlet" method="POST"> 用戶名:<input type="text" name="username"/> 密碼:<input type="password" name="password"/> <input type="submit" value="登錄"/> </form> </body> </html>
LoginServlet.java
1 package com.itheima.session.loginout; 2 3 import java.io.IOException; 4 5 import javax.servlet.ServletException; 6 import javax.servlet.http.HttpServlet; 7 import javax.servlet.http.HttpServletRequest; 8 import javax.servlet.http.HttpServletResponse; 9 10 public class LoginServlet extends HttpServlet { 11 12 public void doGet(HttpServletRequest request, HttpServletResponse response) 13 throws ServletException, IOException { 14 request.setCharacterEncoding("utf-8");//對於17,18行起作用！！！ 15 response.setContentType("text/html;charset=utf-8");//對27行起作用！！！ 16 //1.獲取用戶名密碼 17 String username = request.getParameter("username"); 18 String password = request.getParameter("password"); 19 //2.查詢數據庫檢查用戶名密碼 20 if(UserDao.valiNamePsw(username, password)){ 21 //3.如果正確登錄后重定向到主頁 22 request.getSession().setAttribute("user", username);//設置session標記user 23 response.sendRedirect(request.getContextPath()+"/loginout/index.jsp"); 24 return; 25 }else{ 26 //4.如果錯誤提示 27 response.getWriter().write("用戶名密碼不正確!"); 28 } 29 } 30 31 public void doPost(HttpServletRequest request, HttpServletResponse response) 32 throws ServletException, IOException { 33 doGet(request, response); 34 } 35 36 }
UserDao.java
1 package com.itheima.session.loginout; 2 3 import java.util.HashMap; 4 import java.util.Map; 5 6 public class UserDao { 7 private UserDao() {//工具類的構造方法私有化 8 } 9 private static Map <String,String>map = new HashMap<String, String>();//因為驗證的信息是用戶名、密碼，可以用key、value
的形式，想到用map語法 10 static{//類加載，靜態代碼塊執行 11 map.put("張三豐", "111"); 12 map.put("張翠山", "999"); 13 map.put("張無忌", "888"); 14 map.put("趙敏", "777"); 15 } 16 public static boolean valiNamePsw(String username,String password){ 17 return map.containsKey(username) && map.get(username).equals(password); 18 } 19 }
LogoutServlet.java
1 package com.itheima.session.loginout; 2 3 import java.io.IOException; 4 5 import javax.servlet.ServletException; 6 import javax.servlet.http.HttpServlet; 7 import javax.servlet.http.HttpServletRequest; 8 import javax.servlet.http.HttpServletResponse; 9 10 public class LogoutServlet extends HttpServlet { 11 12 public void doGet(HttpServletRequest request, HttpServletResponse response) 13 throws ServletException, IOException { 14 //1.殺死session 15 //request.getSession()底層的實現，如果發現沒有session立即創建 16 if(request.getSession(false)!=null //如果沒有對應的session，返回null，不會創建session 17 && request.getSession().getAttribute("user")!=null){ 18 // request.getSession(false)!=null && request.getSession().getAttribute("user")!=null 表示有sesson，並且有登錄標記 19 request.getSession().invalidate(); 20 } 21 //2.重定向到主頁 22 response.sendRedirect(request.getContextPath()+"/loginout/index.jsp"); 23 } 24 25 public void doPost(HttpServletRequest request, HttpServletResponse response) 26 throws ServletException, IOException { 27 doGet(request, response); 28 } 29 30 }