对话技术（ Cookie ，Session）_Java相关

会话技术（ Cookie ，Session）

会话技术：
   会话：浏览器访问服务器端，发送多次请求，接受多次响应。直到有一方断开连接。会话结束。

   解决问题：可以使用会话技术，在一次会话的多次请求之间共享数据。

   分类：
       客户端会话技术   Cookie
       服务器端会话技术   Session

客户端会话技术：Cookie 小饼干的意思

       服务器端不需要管理，方便。但是不安全。

       原理：
           1.客户端第一次请求服务器端，服务器作出响应时，会发送set-cookie头，携带需要共享的数据
           2.当客户端接受到这个响应，会将数据存储在客户端
           3.当客户端再次请求服务器端时，会通过cookie请求头携带着存储的数据。
           4.服务器接受带请求，会获取客户端携带的数据。

       Java代码实现：
           1.发送cookie
               //1.创建Cookie对象。
               Cookie c = new Cookie("name","zhangsan");
               //2.通过response发送cookie
               response.addCookie(c);

           2.接收cookie
               //1.获取所有cookie数组
               Cookie[] cs = request.getCookies();
               //2.遍历数组
               if(cs != null){
                   for (Cookie c : cs) {
                       //获取cookie的名称
                       String name = c.getName();
                       //判断名称，得到目标cookie
                       if("name".equals(name)){
                           //获取值
                           String value = c.getValue();
                           System.out.println(name+":"+value);
                       }
                   }
               }

       Cookie的细节：
           1.默认情况下，cookie保存在客户端浏览器内存中。
              需要将数据持久化存储在客户端的硬盘上。
              设置cookie的存活时间。setMaxAge(int s);

           2.Cookie是不支持中文数据的。如果要想存储中文数据。需要转码。
               URL编码

       功能：记住用户名和密码

        服务器端会话技术：Session 主菜的意思

       服务器端需要管理数据，麻烦，但是安全。

       原理：
           1.客户端访问服务器端，在服务器端的一个对象（Session）中存储了数据
           2.服务器给客户端作出响应时，会自动将session对象的id通过响应头 set-cookie:jsessionid=xxx 发送到客户端
           3.客户端接受到响应，将头对应的值存储到客户端
           4.客户端再次请求时，会携带着请求头 cookie：jsessionid=xxx.
           5.服务器接受到请求，通过jsessionid的值，找到对应的session对象。就可以获取对象中存储的数据了。

           Session技术依赖于cookie。

       获取session
           HttpSession session = request.getSession();

       域对象：
           setAttribute():
           getAttribute():
           removeAttribute():

       session细节：
           1.客户端关闭了，两次session一样吗？
               不一样。因为客户端浏览器内存释放了，jsessionid没了。
              服务器关闭了，两次session一样吗？
               不一样。因为服务器内存释放了，session对象没了。
                   session的钝化：
                       当服务器正常关闭时，会将session对象写入到服务器的硬盘上。
                   session的活化：
                       当服务器正常启动时，会将session文件还原为session对象

           2.session对象的销毁
               1.session超时
                   <session-config>
                       <session-timeout>30</session-timeout>
                   </session-config>

               2.invalidate()：session销毁

               3.服务器关闭。

           3.session依赖于cookie，如果客户端禁用了cookie，那么session该咋办？
               URL重写。

           4.getSession方法的重载：
               boolean：
                   true：默认值
                       通过id查找session，如果没找到，新创建一个
                   false：
                       通过id查找session，如果没找到，返回null
                       第一次创建一个新的对象

　　代码演示：

 1 package cookie; 2  3 import java.io.IOException; 4 import java.sql.PreparedStatement; 5 import java.sql.SQLException; 6  7 import javax.servlet.ServletException; 8 import javax.servlet.http.HttpServlet; 9 import javax.servlet.http.HttpServletRequest;10 import javax.servlet.http.HttpServletResponse;11 import javax.servlet.http.HttpSession;12 13 public class LoginServlet extends HttpServlet {14 15     private static final long serialVersionUID = -4372317815130787297L;16 17     public void doGet(HttpServletRequest request, HttpServletResponse response)18             throws ServletException, IOException {19         try {20             //1.获取验证码21             String checkCode = request.getParameter("checkCode");22             //2.获取生成的验证码23             HttpSession session = request.getSession();24             String checkCode_pro = (String) session.getAttribute("checkCode_pro");25             26             //1.设置编码27             request.setCharacterEncoding("utf-8");28             //2.获取用户名和密码29             String username = request.getParameter("username");30             String password = request.getParameter("password");31             //3.操作数据库,获取数据库连接32             //4.定义sql33             //5.获取pstmt对象34             PreparedStatement pstmt = JDBCUtils.getConnection().prepareStatement("select * from user where username = ? and userpassword = ?");35             //6.设置参数36             pstmt.setString(1, username);37             pstmt.setString(2, password);38             //7.执行sql39             //8.验证,判断40             //判断验证码是否正确41             if(checkCode_pro.equalsIgnoreCase(checkCode)){42                     //正确43                     //注册 或 登录44                     session.setAttribute("regist_msg", "验证码正确");45                     if(pstmt.executeQuery().next()){46                     //登陆成功47                     request.setAttribute("username", username);48                     request.getRequestDispatcher("/success.jsp").forward(request, response);49                     }else{50                         //登陆失败51                         request.setAttribute("msg", "用户名或密码错误！");52                         request.getRequestDispatcher("/login.jsp").forward(request, response);    53                     }54             }else{55                 //错误56                 session.setAttribute("regist_msg", "验证码错误");57                 response.sendRedirect("/colloquy/login.jsp");58                 //将session中存储的验证码清空59                 session.removeAttribute("checkCode_pro");    60             }    61         } catch (SQLException e) {62             e.printStackTrace();63         }64     }65 66     public void doPost(HttpServletRequest request, HttpServletResponse response)67             throws ServletException, IOException {68         this.doGet(request, response);69     }70 }

 1 package cookie; 2  3 import java.io.IOException; 4  5 import javax.servlet.ServletException; 6 import javax.servlet.http.Cookie; 7 import javax.servlet.http.HttpServlet; 8 import javax.servlet.http.HttpServletRequest; 9 import javax.servlet.http.HttpServletResponse;10 11 public class RemServlet extends HttpServlet {12 13     private static final long serialVersionUID = -3477344209817695234L;14 15     public void doGet(HttpServletRequest request, HttpServletResponse response)16             throws ServletException, IOException {17         //1.获取用户名和密码，复选框18         String username = request.getParameter("username");19         String password = request.getParameter("password");20         //2.判断用户名和密码是否正确21         if("zhangsan".equals(username) && "123".equals(password)){22             //登陆成功23             if(request.getParameter("rem") != null){24                 //记住密码25                 //1.创建cookie26                 Cookie c_username = new Cookie("username", username);27                 Cookie c_password = new Cookie("password", password);28                 //2.设置存活时间29                 c_username.setMaxAge(60 * 60 * 24 * 7);30                 c_password.setMaxAge(60 * 60 * 24 * 7);31                 //3.发送cookie32                 response.addCookie(c_username);33                 response.addCookie(c_password);34             }35             request.setAttribute("username", username);36             request.getRequestDispatcher("/success.jsp").forward(request, response);37         }else{38             //登陆失败39             request.setAttribute("msg", "用户名或密码错误！");40             request.getRequestDispatcher("/login.jsp").forward(request, response);41         }42     }43 44     public void doPost(HttpServletRequest request, HttpServletResponse response)45             throws ServletException, IOException {46         this.doGet(request, response);47     }48 }

 1 package cookie; 2  3 import java.awt.Color; 4 import java.awt.Graphics; 5 import java.awt.image.BufferedImage; 6 import java.io.IOException; 7 import java.util.Random; 8  9 import javax.imageio.ImageIO;10 import javax.servlet.ServletException;11 import javax.servlet.http.HttpServlet;12 import javax.servlet.http.HttpServletRequest;13 import javax.servlet.http.HttpServletResponse;14 15 /**16  * 生成验证码17  * @author rongsnow18  *19  */20 public class CheckCodeServlet extends HttpServlet {21 22     private static final long serialVersionUID = 8583894656985684165L;23 24     public void doGet(HttpServletRequest request, HttpServletResponse response)25             throws ServletException, IOException {26         27         int width = 100;28         int height = 50;29         //1.创建图片30         BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);31         //2.装饰图片32         //2.1设置背景色33         //2.1.1  获取画笔对象34         Graphics g = image.getGraphics();35         //2.2.2 设置画笔的颜色36         g.setColor(Color.pink);37         //2.2.3 填充背景色38         g.fillRect(0, 0, width, height);39         40         //2.2 画边框41         g.setColor(Color.GREEN);42         g.drawRect(0, 0, width - 1, height - 1);43         44         //2.3 写入验证码45         g.setColor(Color.RED);46         47         String msg = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";48         Random ran = new Random();49         StringBuilder sb = new StringBuilder();50         for (int i = 1; i <= 4; i++) {51             int index = ran.nextInt(msg.length());//随机生成角标52             String s = String.valueOf(msg.charAt(index));53             sb.append(s);54             55             g.drawString(s, width/5 * i, height/2);56         }57         String checkCode_pro = sb.toString();58         //将生成的验证码 存入session59         request.getSession().setAttribute("checkCode_pro", checkCode_pro);60         61         //2.4画干扰线62         g.setColor(Color.BLUE);63         64         for (int i = 0; i < 5; i++) {65             //动态生成坐标点66             int x1 = ran.nextInt(width);67             int x2 = ran.nextInt(width);68             int y1 = ran.nextInt(height);69             int y2 = ran.nextInt(height);70             g.drawLine(x1, y1, x2, y2);71         }72         73         //3.将图片数据 写入到 response输出流中74         ImageIO.write(image, "jpg", response.getOutputStream());75     }76 77     public void doPost(HttpServletRequest request, HttpServletResponse response)78             throws ServletException, IOException {79 80         this.doGet(request, response);81     }82 }

 1 package cookie; 2  3 import java.io.FileNotFoundException; 4 import java.io.FileReader; 5 import java.io.IOException; 6 import java.sql.Connection; 7 import java.sql.DriverManager; 8 import java.sql.ResultSet; 9 import java.sql.SQLException;10 import java.sql.Statement;11 import java.util.Properties;12 13 /**14  * JDBC 工具类15  * @author rongsnow16  *17  */18 public class JDBCUtils {19     private static String url = null;20     private static String user = null;21     private static String password = null;22     private static String driverClass = null;23     24     static{25         /*26          * 加载配置文件，为每一个值赋值27          */28         try {29             //1.创建properties对象30             Properties pro = new Properties();31             //获取配置文件的真实路径32             //2.关联资源文件33             pro.load(new FileReader(JDBCUtils.class.getClassLoader().getResource("jdbc.properties").getPath()));34             //3.获取数据35             url = pro.getProperty("url");36             user = pro.getProperty("user");37             password = pro.getProperty("password");38             driverClass = pro.getProperty("driverClass");39             //4.注册驱动40             Class.forName(driverClass);41             42         } catch (FileNotFoundException e) {43             e.printStackTrace();44         } catch (IOException e) {45             e.printStackTrace();46         } catch (ClassNotFoundException e) {47             e.printStackTrace();48         }49     }50     51     /**52      * 获取数据库连接53      * @throws SQLException 54      */55     public static Connection getConnection() throws SQLException{56         57         return DriverManager.getConnection(url, user, password);58     }59     60     /**61      * 释放资源62      * @throws SQLException 63      */64     public static void close(Connection conn,Statement stmt,ResultSet rs) throws SQLException{65         if(rs != null){//预防空指针异常66             rs.close();67         }68         if(stmt != null){//预防空指针异常69             stmt.close();70         }71         if(conn != null){//预防空指针异常72             conn.close();73         }74     }75     public static void close(Connection conn,Statement stmt) throws SQLException{76         if(stmt != null){//预防空指针异常77             stmt.close();78         }79         if(conn != null){//预防空指针异常80             conn.close();81         }82     }83     public static void close(Connection conn) throws SQLException{84         if(conn != null){//预防空指针异常85             conn.close();86         }87     }88 }

　　web.xml

 1 <?xml version="1.0" encoding="UTF-8"?> 2 <web-app version="2.5"  3     xmlns="http://java.sun.com/xml/ns/javaee"  4     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  5     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee  6     http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> 7   <display-name></display-name>     8    9     <servlet>10         <description>This is the description of my J2EE component</description>11         <display-name>This is the display name of my J2EE component</display-name>12         <servlet-name>LoginServlet</servlet-name>13         <servlet-class>cookie.LoginServlet</servlet-class>14     </servlet>15     <servlet>16         <description>This is the description of my J2EE component</description>17         <display-name>This is the display name of my J2EE component</display-name>18         <servlet-name>RemServlet</servlet-name>19         <servlet-class>cookie.RemServlet</servlet-class>20     </servlet>21     <servlet>22         <description>This is the description of my J2EE component</description>23         <display-name>This is the display name of my J2EE component</display-name>24           <servlet-name>checkcode</servlet-name>25           <servlet-class>cookie.CheckCodeServlet</servlet-class>26       </servlet>27 28 29     <servlet-mapping>30         <servlet-name>LoginServlet</servlet-name>31         <url-pattern>/loginServlet</url-pattern>32     </servlet-mapping>33     <servlet-mapping>34         <servlet-name>RemServlet</servlet-name>35         <url-pattern>/remServlet</url-pattern>36     </servlet-mapping>37     <servlet-mapping>38           <servlet-name>checkcode</servlet-name>39           <url-pattern>/checkCodeServlet</url-pattern>40       </servlet-mapping>41       42       43   <welcome-file-list>44       <welcome-file>index.jsp</welcome-file>45   </welcome-file-list>46 </web-app>

　　jdbc.properties配置文件内容

driverClass=com.mysql.jdbc.Driver
url=jdbc:mysql:///mydb
user=root
password=123

login.jsp

 1 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> 2  3 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 4 <html> 5     <head> 6         <title>My JSP 'login.jsp' starting page</title> 7         <script type="text/javascript"> 8             function changeImg(){ 9                 document.getElementById("img").src = "/colloquy/checkCodeServlet?time="+new Date().getTime();10             }11             function changeImg2(obj){12                 obj.src = "/colloquy/checkCodeServlet?time="+new Date().getTime();13             }14         </script>15     </head>16     <body>17         <%18             //1.获取所有cookie19             Cookie[] cs = request.getCookies();20             String username = "";21             String password = "";22             //2.遍历cookie数组23             if(cs != null){24                 for(Cookie c : cs){25                     //获取名称26                     String name = c.getName();27                     if("username".equals(name)){28                         username = c.getValue();29                     }30                     if("password".equals(name)){31                         password = c.getValue();32                     }33                 }34             }    35         %>36         37         <form action="/colloquy/loginServlet" method="post">    38             <table align="center" bgcolor="pink">39                 <caption>用户登陆</caption>40                 <tr>41                     <td>用户名：</td>42                     <td><input type="text" name="username"></td>43                 </tr>44                 <tr>45                     <td>密码：</td>46                     <td><input type="password" name="password"></td>47                 </tr>48                 <tr>49                     <td>验证码：</td>50                     <td><input type="text" name="checkCode"></td>51                     <td><img src="/colloquy/checkCodeServlet" id="img" onclick="changeImg2(this);"></td>52                     <td><a href="javascript:void(0);" onclick="changeImg();">看不清?</a><br></td>53                 <tr>54                 <tr>55                     <td>记住密码</td>56                     <td><input type="checkbox" name="rem"></td>57                 </tr>58                 <tr>59                     <td colspan="2" align="center" ><input type="submit" value="登陆"></td>60                 </tr>61             </table>62         </form>63         <div align="center" style="color:red;"><%=request.getAttribute("msg")==null ? "" : request.getAttribute("msg") %></div>64         <div align="center" style="color:#FF0000;"><%=session.getAttribute("regist_msg")==null ? "" : session.getAttribute("regist_msg") %></div>65     </body>66 </html>

success.jsp

 1 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> 2  3 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 4 <html> 5     <head> 6             <title>My JSP 'success.jsp' starting page</title> 7     </head> 8     <body> 9         10         <%=11             request.getAttribute("username")12         %>,欢迎您！13         14     </body>15 </html>

所使用的MySQL语句

 1 -- 创建用户信息表 user,并指定主键且自增长 2 CREATE TABLE USER( 3     uid        INT PRIMARY KEY AUTO_INCREMENT, 4     username    VARCHAR(32), 5     userpassword    VARCHAR(32)     6 ); 7  8 -- 查询所有列 9 SELECT * FROM USER;10 11 -- 添加数据12 INSERT INTO USER(username,userpassword) VALUE ('zhangsan','123');13 INSERT INTO USER(username,userpassword) VALUE ('lisi','1234');14 INSERT INTO USER(username,userpassword) VALUE ('wangwu','234');15 INSERT INTO USER(username,userpassword) VALUE ('zhaoliu','1234');16 INSERT INTO USER(username,userpassword) VALUE ('sisi','234');