session对象的概念（Session详解，学习 Session对象一篇文章就够了）

目录

1 Session概述

2 Session原理

3 Session使用

3.1 获取Session

3.2 Session保存数据

3.3 Session获取数据

3.4 Session移除数据

4 Session与Request应用区别

4.1 Session和request存储数据

4.2 获取session和request中的值

4.3 session和request区别效果

5 Session的声明周期

5.1 Session有效时间设置

5.2 session销毁

.6 浏览器禁用Cookie解决方案（了解）

6.1 浏览器禁用Cookie的后果

6.2 URL重写

6.3 实现URL重写

7 Session实战权限验证

7.1 创建管理员表manager并添加数据

7.2 创建Web项目

7.3 基础环境搭建

7.4 登录页面

7.5 LoginMgrController

7.6 ShowAllManagerController

7.7 ShowAllManagerJsp

8 Session实战保存验证码

8.1 创建验证码

8.2 登录页面

8.3 LoginMgrController

8.4 ShowAllManagerController

今天的分享就到此结束了

创作不易点赞评论互关三连

1 Session概述

（1）Session用于记录用户的状态            。Session指的是一段时间内            ，单个客户端与Web服务器的一连串相关的交互过程
  
 
  
 
  
 
  
 
  
 
  
 。

（2）在一个Session中
  
 
  
 
  
 
  
 
  
 
  
 ，客户可能会多次请求访问同一个资源











，也有可能请求访问各种不同的服务器资源











。

（3）Session是由服务器端创建的

2 Session原理

（1）Session会为每一次会话分配一个Session对象

（2）同一个浏览器发起的多次请求 
  
  
  
  
  
 ，同属于一次会话（Session）

（3）首次使用到Session时
  
  
  
  
  
  ，服务器会自动创建Session
 


 


 


 


 


 

，并创建Cookie存储SessionId发送回客户端

3 Session使用

Session作用域：拥有存储数据的空间 
 
 
 
 
 
，作用范围是一次会话有效

一次会话是使用同一浏览器发送的多次请求 
  
  
  
  
  
 。一旦浏览器关闭
   
   
   
   
   
   ，则结束会话

可以将数据存入Session中
 

 

 

 

 

 
，在一次会话的任意位置进行获取

可传递任何数据（基本数据类型            、对象
  
 
  
 
  
 
  
 
  
 
  
 、集合











、数组）

3.1 获取Session

Session是服务器端自动创建的 

 

 

 

 

 

，通过request对象获取

package com.cxyzxc.www.servlet01; import javax.servlet.*; import javax.servlet.http.*; import javax.servlet.annotation.*; import java.io.IOException; @WebServlet(name = "SessionServlet01", value = "/SessionServlet01") public class SessionServlet01 extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置请求参数的编码格式            ，这种方式对get请求方式无效 request.setCharacterEncoding("UTF-8"); //设置响应编码格式为UTF-8 response.setContentType("text/html;charset=UTF-8"); //获取Session对象,首次使用到Session时

 
 

 
 

 
 

 
 

 
 

 
 ，服务器会自动创建Session











，并创建Cookie存储SessionId发送回客户端 HttpSession session = request.getSession(); System.out.println("ID:" + session.getId());//唯一标记 } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }

3.2 Session保存数据

使用setArrtibute(属性名,Object)保存数据到session中

package com.cxyzxc.www.servlet01; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import java.io.IOException; @WebServlet(name = "SessionServlet02", value = "/SessionServlet02") public class SessionServlet02 extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置请求参数的编码格式                  ，这种方式对get请求方式无效 request.setCharacterEncoding("UTF-8"); //设置响应编码格式为UTF-8 response.setContentType("text/html;charset=UTF-8"); //获取Session对象,首次使用到Session时
 
 
 
 
 
 
 
 
 
 
 
 ，服务器会自动创建Session

















，并创建Cookie存储SessionId发送回客户端 HttpSession session = request.getSession(); //将数据存储以键值对的形式到session对象中            ，可传递任何数据（基本数据类型 
  
  
  
  
  
 、对象
  
  
  
  
  
  、集合
 


 


 


 


 


 

、数组） session.setAttribute("username","张三"); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }

3.3 Session获取数据

（1）使用getAttribute("属性名");获取session中数据
  
  
  
  
  
  。

（2）先访问SessionServlet02将数据存储到session对象中
  
 
  
 
  
 
  
 
  
 
  
 ，然后通过GetSessionValueServlet01请求获取session中的数据

package com.cxyzxc.www.servlet01; import javax.servlet.*; import javax.servlet.http.*; import javax.servlet.annotation.*; import java.io.IOException; @WebServlet(name = "GetSessionValueServlet01", value = "/GetSessionValueServlet01") public class GetSessionValueServlet01 extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置请求参数的编码格式











，这种方式对get请求方式无效 request.setCharacterEncoding("UTF-8"); //设置响应编码格式为UTF-8 response.setContentType("text/html;charset=UTF-8"); //获取Session对象 HttpSession session = request.getSession(); //获取session对象中的值 
  
  
  
  
  
 ，获取的值是Object类型
  
  
  
  
  
  ，转换为其对应的类型 String username = (String) session.getAttribute("username"); System.out.println("session对象中存储的username值：" + username); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }

3.4 Session移除数据

（1）使用removeAttribute("属性名");从session中删除数据

（2）向请求SessionServlet02向session对象中存储数据
 


 


 


 


 


 

，然后访问GetSessionValueServlet01可以获取session对象中的值 
 
 
 
 
 
，再访问SessionServlet03移除session对象中存储的数据
   
   
   
   
   
   ，最后访问GetSessionValueServlet01获取session对象中的值为null

package com.cxyzxc.www.servlet01; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import java.io.IOException; @WebServlet(name = "SessionServlet03", value = "/SessionServlet03") public class SessionServlet03 extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置请求参数的编码格式
 

 

 

 

 

 
，这种方式对get请求方式无效 request.setCharacterEncoding("UTF-8"); //设置响应编码格式为UTF-8 response.setContentType("text/html;charset=UTF-8"); //获取Session对象,首次使用到Session时 

 

 

 

 

 

，服务器会自动创建Session            ，并创建Cookie存储SessionId发送回客户端 HttpSession session = request.getSession(); //通过键移除session作用域中的值 session.removeAttribute("username"); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }

4 Session与Request应用区别

（1）request是一次请求有效

 
 

 
 

 
 

 
 

 
 

 
 ，请求改变











，则request改变

（2）session是一次会话有效                  ，浏览器改变
 
 
 
 
 
 
 
 
 
 
 
 ，则session改变

4.1 Session和request存储数据

package com.cxyzxc.www.servlet01; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import java.io.IOException; @WebServlet(name = "SessionServlet04", value = "/SessionServlet04") public class SessionServlet04 extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置请求参数的编码格式

















，这种方式对get请求方式无效 request.setCharacterEncoding("UTF-8"); //设置响应编码格式为UTF-8 response.setContentType("text/html;charset=UTF-8"); //获取Session对象 HttpSession session = request.getSession(); //使用session存储数据 session.setAttribute("username","zhangsan"); //使用request存储数据 request.setAttribute("password","123456"); //重定向 response.sendRedirect("/webProject10_war_exploded/GetSessionValueServlet01"); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }

4.2 获取session和request中的值

package com.cxyzxc.www.servlet01; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import java.io.IOException; @WebServlet(name = "GetSessionValueServlet01", value = "/GetSessionValueServlet01") public class GetSessionAndRequestValueServlet01 extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置请求参数的编码格式            ，这种方式对get请求方式无效 request.setCharacterEncoding("UTF-8"); //设置响应编码格式为UTF-8 response.setContentType("text/html;charset=UTF-8"); //获取Session对象 HttpSession session = request.getSession(); //获取session对象中的值
  
 
  
 
  
 
  
 
  
 
  
 ，获取的值是Object类型











，转换为其对应的类型 String username = (String) session.getAttribute("username"); //获取request对象中的值 
  
  
  
  
  
 ，获取的值是Object类型
  
  
  
  
  
  ，转换为其对应的类型 String password = (String) request.getAttribute("password"); System.out.println("session对象中存储的username值：" + username); System.out.println("request对象中存储的password值：" + password); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }

4.3 session和request区别效果

5 Session的声明周期

开始

第一次使用到Session的请求产生
 


 


 


 


 


 

，则创建Session

结束

浏览器关闭 
 
 
 
 
 
，则失效

Session超时
   
   
   
   
   
   ，则失效

session.setMaxInactiveInterval(seconds);//设置最大有效时间（单位：秒）

手工销毁
 

 

 

 

 

 
，则失效

session.invalidate();//登录退出 

 

 

 

 

 

，销毁

5.1 Session有效时间设置

SessionServlet05类设置session有效期为20秒            ，先通过请求SessionServlet05类将session存储在

 
 

 
 

 
 

 
 

 
 

 
 ，然后在20秒内第一次在GetSessionValueServlet02获取sessionID值











，与SessionServlet05类中输出的id值一致                  ，过20秒后在GetSessionValueServlet02类中输出的sessionID值不一致了

package com.cxyzxc.www.servlet01; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import java.io.IOException; @WebServlet(name = "SessionServlet05", value = "/SessionServlet05") public class SessionServlet05 extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置请求参数的编码格式
 
 
 
 
 
 
 
 
 
 
 
 ，这种方式对get请求方式无效 request.setCharacterEncoding("UTF-8"); //设置响应编码格式为UTF-8 response.setContentType("text/html;charset=UTF-8"); //获取Session对象,首次使用到Session时

















，服务器会自动创建Session            ，并创建Cookie存储SessionId发送回客户端 HttpSession session = request.getSession(); //设置session有效期,时间单位为秒 session.setMaxInactiveInterval(20); //输出sessionid值 System.out.println("SessionServlet05类中输出ID:"+session.getId()); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }

5.2 session销毁

先使用GetSessionValueServlet03类获取session的id值
  
 
  
 
  
 
  
 
  
 
  
 ，然后使用GetSessionValueServlet04类获取session的id值











，两个类获取的id值一致 
  
  
  
  
  
 ，在GetSessionValueServlet04类中输出id值后销毁了session
  
  
  
  
  
  ，然后再在GetSessionValueServlet03类中获取id值
 


 


 


 


 


 

，就不一致了 
 
 
 
 
 
，就是服务器新建的session对象了

5.2.1 GetSessionValueServlet03类

package com.cxyzxc.www.servlet01; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import java.io.IOException; @WebServlet(name = "GetSessionValueServlet03", value = "/GetSessionValueServlet03") public class GetSessionValueServlet03 extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置请求参数的编码格式
   
   
   
   
   
   ，这种方式对get请求方式无效 request.setCharacterEncoding("UTF-8"); //设置响应编码格式为UTF-8 response.setContentType("text/html;charset=UTF-8"); //获取Session对象 HttpSession session = request.getSession(); //输出sessionid值 System.out.println("GetSessionValueServlet03类中输出ID:"+session.getId()); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }

5.2.2 GetSessionValueServlet04类

package com.cxyzxc.www.servlet01; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import java.io.IOException; @WebServlet(name = "GetSessionValueServlet04", value = "/GetSessionValueServlet04") public class GetSessionValueServlet04 extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置请求参数的编码格式
 

 

 

 

 

 
，这种方式对get请求方式无效 request.setCharacterEncoding("UTF-8"); //设置响应编码格式为UTF-8 response.setContentType("text/html;charset=UTF-8"); //获取Session对象 HttpSession session = request.getSession(); //输出sessionid值 System.out.println("GetSessionValueServlet04类中输出ID:"+session.getId()); //销毁session session.invalidate(); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }

.6 浏览器禁用Cookie解决方案（了解）

6.1 浏览器禁用Cookie的后果

服务器在默认情况下 

 

 

 

 

 

，会使用Cookie的方式将sessionID发送给浏览器            ，如果用户禁止Cookie

 
 

 
 

 
 

 
 

 
 

 
 ，则sessionID不会被浏览器保存











，此时                  ，服务器可以使用URL重写这样的方式来发送sessionID

多次请求GetSessionValueServlet05类输出的session的id值都不相同
 
 
 
 
 
 
 
 
 
 
 
 ，并且在网站的Cookie对象中没有session的id值存在

6.2 URL重写

浏览器在访问服务器上的某个地址时

















，不再使用原来的那个地址            ，而是使用经过改写的地址（即在原来的地址后面加上了sessionID）

6.3 实现URL重写

response.encodeRedirectURL(String url)生成重写的URL

6.3.1 重写URL

package com.cxyzxc.www.servlet01; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import java.io.IOException; @WebServlet(name = "GetSessionValueServlet06", value = "/GetSessionValueServlet06") public class GetSessionValueServlet06 extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置请求参数的编码格式
  
 
  
 
  
 
  
 
  
 
  
 ，这种方式对get请求方式无效 request.setCharacterEncoding("UTF-8"); //设置响应编码格式为UTF-8 response.setContentType("text/html;charset=UTF-8"); //获取Session对象 HttpSession session = request.getSession(); //输出sessionid值 System.out.println("GetSessionValueServlet06类中输出ID:"+session.getId()); //重写URL追加session值 String newURL = response.encodeURL("/webProject10_war_exploded/GetSessionValueServlet07"); System.out.println("重写后的URL："+newURL); //重定向 response.sendRedirect(newURL); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }

6.3.1 获取session

package com.cxyzxc.www.servlet01; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import java.io.IOException; @WebServlet(name = "GetSessionValueServlet07", value = "/GetSessionValueServlet07") public class GetSessionValueServlet07 extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置请求参数的编码格式











，这种方式对get请求方式无效 request.setCharacterEncoding("UTF-8"); //设置响应编码格式为UTF-8 response.setContentType("text/html;charset=UTF-8"); //获取Session对象 HttpSession session = request.getSession(); //输出sessionid值 System.out.println("GetSessionValueServlet07类中输出ID:"+session.getId()); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }

7 Session实战权限验证

7.1 创建管理员表manager并添加数据

7.2 创建Web项目

创建Web项目 
  
  
  
  
  
 ，导入相关jar包

commons-dbutils-1.7.jar

druid-1.1.5.jar

mysql-connector-java-5.1.25-bin.jar

servlet-api.jar

7.3 基础环境搭建

在项目下创建包目录结构如下

com.cxyzxc.www.controller包：调用业务逻辑Servlet

com.cxyzxc.www.dao包：数据访问层接口

com.cxyzxc.www.dao.impl包：数据访问层接口实现类

com.cxyzxc.www.entity包：实体类

com.cxyzxc.www.jsp包：打印显示页面Servlet

com.cxyzxc.www.service包：业务逻辑层接口

com.cxyzxc.www.service.impl包：业务逻辑层接口实现类

com.cxyzxc.www.utils包：工具类

database.properties:数据库连接及连接池配置文件

7.4 登录页面

7.4.1 login.html

<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>管理员登录页面</title> <link type="text/css" rel="stylesheet" href="css/login.css"/> </head> <body> <div> <form action="LoginMgrController" method="post"> <p> 账号：<input type="text" name="username"/> </p> <p> 密码：<input type="password" name="password"/> </p> <p> <input type="submit" value="登录"/> </p> </form> </div> </body> </html>

7.4.2 login.css

* { margin: 0; padding: 0; } div { width: 400px; background-color: #ccc; margin: 30px auto; padding-top: 30px; text-align: center; } p { margin-top: 10px; } input { outline: none; }

7.5 LoginMgrController

package com.cxyzxc.www.controller; import com.cxyzxc.www.entity.Manager; import com.cxyzxc.www.service.ManagerService; import com.cxyzxc.www.service.impl.ManagerServiceImpl; import javax.servlet.*; import javax.servlet.http.*; import javax.servlet.annotation.*; import java.io.IOException; @WebServlet(name = "LoginMgrController", value = "/LoginMgrController") public class LoginMgrController extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //1 
 
 
 
 
 
、处理乱码 request.setCharacterEncoding("UTF-8"); response.setContentType("text/html;charset=UTF-8"); //2
   
   
   
   
   
   、收参（获取客户端发送过来的请求数据） String username = request.getParameter("username"); String password = request.getParameter("password"); //3
 

 

 

 

 

 
、调用业务方法 ManagerService managerService = new ManagerServiceImpl(); Manager manager = managerService.login(username, password); //4 

 

 

 

 

 

、处理结果
  
  
  
  
  
  ，根据结果做不同的跳转 if (manager != null) {//manager不为null
 


 


 


 


 


 

，说明账号和密码正确 
 
 
 
 
 
，登录成功 //将获取的账号和密码信息存储在session中 HttpSession session = request.getSession(); session.setAttribute("manager", manager); //跳转到显示所有管理员信息的Servlet response.sendRedirect("/managerProject01_war_exploded/ShowAllManagerController"); } else {//manager为null
 


 


 


 


 


 

。说明账号或者密码错误
   
   
   
   
   
   ，登录失败 response.sendRedirect("/managerProject01_war_exploded/login.html"); } } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }

7.6 ShowAllManagerController

package com.cxyzxc.www.controller; import com.cxyzxc.www.entity.Manager; import com.cxyzxc.www.service.ManagerService; import com.cxyzxc.www.service.impl.ManagerServiceImpl; import javax.servlet.*; import javax.servlet.http.*; import javax.servlet.annotation.*; import java.io.IOException; import java.util.List; @WebServlet(name = "ShowAllManagerController", value = "/ShowAllManagerController") public class ShowAllManagerController extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //1            、处理乱码 request.setCharacterEncoding("UTF-8"); response.setContentType("text/html;charset=UTF-8"); //通过HttpSession完成权限控制 HttpSession session =request.getSession(); //获取session中存储的值 Manager manager = (Manager)session.getAttribute("manager"); //判断获取的值 if(manager!=null){ //调用业务,只做业务
 

 

 

 

 

 
，业务与显示分离 ManagerService managerService = new ManagerServiceImpl(); List<Manager> managers =managerService.showAllManager(); //将获取的数据存储在request作用域中 request.setAttribute("managers",managers); //转发 

 

 

 

 

 

，跳转到显示结果的Servlet request.getRequestDispatcher("/ShowAllManagerJsp").forward(request,response); }else{ //说明没有登录            ，要先去登录才能进行显示 response.sendRedirect("/managerProject01_war_exploded/login.html"); } } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }

7.7 ShowAllManagerJsp

package com.cxyzxc.www.jsp; import com.cxyzxc.www.entity.Manager; import javax.servlet.*; import javax.servlet.http.*; import javax.servlet.annotation.*; import java.io.IOException; import java.io.PrintWriter; import java.util.List; @WebServlet(name = "ShowAllManagerJsp", value = "/ShowAllManagerJsp") public class ShowAllManagerJsp extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //1

 
 

 
 

 
 

 
 

 
 

 
 、处理乱码 request.setCharacterEncoding("UTF-8"); response.setContentType("text/html;charset=UTF-8"); //2











、获取数据 List<Manager> managers = (List<Manager>) request.getAttribute("managers"); //获取输出流 PrintWriter printWriter = response.getWriter(); if (managers.size() != 0) { printWriter.println("<html>"); printWriter.println("<head>"); printWriter.println("<title>所有管理员</title>"); printWriter.println("<link type=\"text/css\" rel=\"stylesheet\" href=\"css/table.css\" />"); printWriter.println("</head>"); printWriter.println("<table border=1px cellspacing=0>"); printWriter.println("<tr>"); printWriter.println(" <th>序号</th>"); printWriter.println(" <th>账号</th>"); printWriter.println(" <th>密码</th>"); printWriter.println(" <th>操作</th>"); printWriter.println(" </tr>"); for (int i = 0; i < managers.size(); i++) { printWriter.println("<tr>"); printWriter.println("<td>" + (i + 1) + "</td>"); printWriter.println("<td>" + managers.get(i).getUsername() + "</td>"); printWriter.println("<td>" + managers.get(i).getPassword() + "</td>"); printWriter.println("<td><a href=\"#\">修改</a> <a href=\"#\">删除</a></td>"); printWriter.println("</tr>"); } printWriter.println("</table>"); printWriter.println("</html>"); } else { printWriter.println("<h2>数据库中没有数据查询</h2>"); } } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }

8 Session实战保存验证码

生成验证码的方式有很多种

 
 

 
 

 
 

 
 

 
 

 
 ，可以使用随机数的方式实现











，也可以使用ValidateCode类来实现（需要导入ValidateCode.jar包） 
 
 
 
 
 
。在这里                  ，我们学习使用ValidateCode类来生成验证码

8.1 创建验证码

package com.cxyzxc.www.controller; import cn.dsna.util.images.ValidateCode; import javax.servlet.*; import javax.servlet.http.*; import javax.servlet.annotation.*; import java.io.IOException; /** * 此Servlet的作用是生成验证码并将生成的验证码存储到session中                  、发送到页面中显示 */ @WebServlet(name = "VerificationServlet", value = "/VerificationServlet") public class VerificationServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置验证码规格 ValidateCode validateCode = new ValidateCode(200, 20, 4, 10); //获取验证码 String code = validateCode.getCode(); //将验证码存储在session中 HttpSession session = request.getSession(); session.setAttribute("code",code); //将验证码输出到客户端 validateCode.write(response.getOutputStream()); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }

8.2 登录页面

<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>管理员登录页面</title> <link type="text/css" rel="stylesheet" href="css/login.css"/> </head> <body> <div> <form action="LoginMgrController" method="post"> <p> 账号：<input type="text" name="username"/> </p> <p> 密码：<input type="password" name="password"/> </p> <p> 验证码：<input type="text" name="verification"/> <img src="/managerProject02_war_exploded/VerificationServlet" /> </p> <p> <input type="submit" value="登录"/> </p> </form> </div> </body> </html>

8.3 LoginMgrController

package com.cxyzxc.www.controller; import com.cxyzxc.www.entity.Manager; import com.cxyzxc.www.service.ManagerService; import com.cxyzxc.www.service.impl.ManagerServiceImpl; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import java.io.IOException; @WebServlet(name = "LoginMgrController", value = "/LoginMgrController") public class LoginMgrController extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //1
 
 
 
 
 
 
 
 
 
 
 
 、处理乱码 request.setCharacterEncoding("UTF-8"); response.setContentType("text/html;charset=UTF-8"); //2

















、收参（获取客户端发送过来的请求数据） String username = request.getParameter("username"); String password = request.getParameter("password"); String inputCodde = request.getParameter("verification"); //获取session中的验证码 HttpSession session = request.getSession(); String codes = (String) session.getAttribute("code"); if (!inputCodde.isEmpty() && inputCodde.equalsIgnoreCase(codes)) { //3            、调用业务方法 ManagerService managerService = new ManagerServiceImpl(); Manager manager = managerService.login(username, password); //4
  
 
  
 
  
 
  
 
  
 
  
 、处理结果
 
 
 
 
 
 
 
 
 
 
 
 ，根据结果做不同的跳转 if (manager != null) {//manager不为null

















，说明账号和密码正确            ，登录成功 //将获取的账号和密码信息存储在session中 HttpSession session2 = request.getSession(); session2.setAttribute("manager", manager); //跳转到显示所有管理员信息的Servlet response.sendRedirect("/managerProject02_war_exploded/ShowAllManagerController"); } else {//manager为null
   
   
   
   
   
   。说明账号或者密码错误
  
 
  
 
  
 
  
 
  
 
  
 ，登录失败 response.sendRedirect("/managerProject02_war_exploded/login.html"); } } else {//验证码不对











，重新登录 response.sendRedirect("/managerProject02_war_exploded/login.html"); } } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }

8.4 ShowAllManagerController

package com.cxyzxc.www.controller; import com.cxyzxc.www.entity.Manager; import com.cxyzxc.www.service.ManagerService; import com.cxyzxc.www.service.impl.ManagerServiceImpl; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import java.io.IOException; import java.util.List; @WebServlet(name = "ShowAllManagerController", value = "/ShowAllManagerController") public class ShowAllManagerController extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //通过HttpSession完成权限控制 HttpSession session =request.getSession(); //获取session中存储的值 Manager manager = (Manager)session.getAttribute("manager"); //判断获取的值 if(manager!=null){ //调用业务,只做业务 
  
  
  
  
  
 ，业务与显示分离 ManagerService managerService = new ManagerServiceImpl(); List<Manager> managers =managerService.showAllManager(); //将获取的数据存储在request作用域中 request.setAttribute("managers",managers); //转发
  
  
  
  
  
  ，跳转到显示结果的Servlet request.getRequestDispatcher("/ShowAllManagerJsp").forward(request,response); }else{ //说明没有登录
 


 


 


 


 


 

，要先去登录才能进行显示 response.sendRedirect("/managerProject02_war_exploded/login.html"); } } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }

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