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  • servlet编写用户注册登录系统，登录成功后显示此用户的登录次数

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    代码如下：

    CheckUser.java

      1 package com.wyd.www;
  2 import java.io.*;
  3 import java.sql.*;
  4 
  5 import javax.servlet.*;
  6 import javax.servlet.http.*;
  7 
  8 /**
  9  * 
 10  * @date 2014-05-21
 11  * @author asif
 12  * @检测用户名哥密码的合法性
 13  *
 14  */
 15 
 16 @SuppressWarnings("serial")
 17 public class CheckUser extends HttpServlet{
 18     public void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException
 19     {
 20         //HttpSession session = request.getSession();
 21         response.setContentType("Text/html;charset=GB2312");
 22         request.setCharacterEncoding("GB2312");
 23         String name = request.getParameter("username");
 24         String passwd = request.getParameter("pwd");
 25         int totlogin = 0;
 26         //获得输出流
 27         PrintWriter out = response.getWriter();
 28         User account = new User();
 29         account.SetPassword(passwd);
 30         account.SetUsername(name);
 31         //判断用户名是否为空
 32         if(name.trim().equals(""))
 33         {
 34             out.println("<html>");
 35             out.println("<head>");
 36             out.println("<meta http-equiv="Refresh" content="2;url= login.jsp">");
 37             out.println("<title>Wait 2s</title>");
 38             out.println("</head>");
 39             out.println("<body>用户名不能为空</body>");
 40             out.println("</html>");
 41         }
 42         else
 43         {
 44             //连接数据库查看用户名是否存在和其密码是否正确
 45             Connection conn = MysqlConnection();
 46             PreparedStatement pstmt = null;
 47             ResultSet rset = null;
 48             String sql = "select * from user where username=?";
 49             try {
 50                 pstmt = conn.prepareStatement(sql);
 51                 pstmt.setString(1, name);
 52                 rset = pstmt.executeQuery();
 53             } catch (SQLException e1) {
 54                 // TODO Auto-generated catch block
 55                 e1.printStackTrace();
 56             }
 57             //flag标记用户名和密码是否对应成功，如果对应正确为true，否则为false
 58             boolean flag = true;
 59             try {
 60                 if(rset == null)
 61                 {
 62                     //out.close();
 63                     //conn.close();
 64                     /*out.println("<html>");
 65                     out.println("<head>");
 66                     out.println("<meta http-equiv="Refresh" content="2;url= login.jsp">");
 67                     out.println("<title>Wait 2s</title>");
 68                     out.println("</head>");
 69                     out.println("<body>用户名不存在</body>");
 70                     out.println("</html>");*/
 71                 }
 72                 else
 73                 {
 74                     while(rset.next())
 75                     {
 76                         String Passwordtemp = rset.getString("password");
 77                         if(passwd.equals(Passwordtemp))
 78                         {
 79                             totlogin = rset.getInt("totlogin");
 80                             totlogin++;
 81                             account.SetTotlogin(totlogin);
 82                             //登录次数加一
 83                             sql = "update user set totlogin=? where username=?";
 84                             pstmt = conn.prepareStatement(sql);
 85                             pstmt.setInt(1, totlogin);
 86                             pstmt.setString(2, name);
 87                             pstmt.executeUpdate();//更新完成
 88                             flag = false;
 89                             break;
 90                         }
 91                     }
 92                 }
 93                 conn.close();
 94             } catch (SQLException e) {
 95                 // TODO Auto-generated catch block
 96                 e.printStackTrace();
 97             }
 98             //根据上面得到的flag的值判断是否正确，并向不同的页面跳转
 99             if(!flag)
100             {
101                 out.println("<html>");
102                 out.println("<head>");
103                 out.println("<title>login successful</title>");
104                 out.println("</head>");
105                 out.println("<body>登陆成功!这是你的第 "+totlogin+" 次登录</body>");
106                 out.println("</html>");
107             }
108             else
109             {
110                 out.println("<html>");
111                 out.println("<head>");
112                 out.println("<meta http-equiv="Refresh" content="2;url= login.jsp">");
113                 out.println("<title>Wait 2s</title>");
114                 out.println("</head>");
115                 out.println("<body>用户名或密码错误</body>");
116                 out.println("</html>");
117             }
118         }
119         out.close();
120     }
121     //连接数据库函数
122     public static Connection MysqlConnection()
123     {
124         String username = "root";
125         String userpasswd = "123456";
126         String url = "jdbc:mysql://127.0.0.1:3306/test";
127         try
128         {
129             Class.forName("com.mysql.jdbc.Driver").newInstance();
130             try
131             {
132                 Connection contemp = DriverManager.getConnection(url, username, userpasswd);
133                 return contemp;
134             }
135             catch (SQLException e)
136             {
137                 // TODO Auto-generated catch block
138                 e.printStackTrace();
139             }
140         }
141         catch (InstantiationException e)
142         {
143             // TODO Auto-generated catch block
144             e.printStackTrace();
145         }
146         catch (ClassNotFoundException e) {
147             // TODO Auto-generated catch block
148             e.printStackTrace();
149         } catch (IllegalAccessException e1) {
150             // TODO Auto-generated catch block
151             e1.printStackTrace();
152         }
153         return null;
154     }
155 }
    View Code

    User.java

     1 package com.wyd.www;
 2 
 3 /**
 4  * 
 5  * @date 2014-05-21
 6  * @author asif
 7  * 用户登录系统-用户账户类
 8  *
 9  */
10 
11 public class User {
12     private static String username = "";
13     private static String password = "";
14     private static int totlogin = 0;
15     //获得密码
16     public String GetPassword()
17     {
18         return password;
19     }
20     //传入密码
21     @SuppressWarnings("static-access")
22     public void SetPassword(String password)
23     {
24         this.password = password;
25     }
26     //获取用户名
27     public String GetUsername()
28     {
29         return username;
30     }
31     //传入用户名
32     @SuppressWarnings("static-access")
33     public void SetUsername(String username)
34     {
35         this.username = username;
36     }
37     //获取登录次数
38     public int GetTotlogin()
39     {
40         return totlogin;
41     }
42     //传入用户的登录次数
43     @SuppressWarnings("static-access")
44     public void SetTotlogin(int totlogin)
45     {
46         this.totlogin = totlogin;
47     }
48 }
    View Code

    CheckRegister.java

      1 package com.yqr.www;
  2 
  3 import java.io.*;
  4 import java.sql.Connection;
  5 import java.sql.DriverManager;
  6 import java.sql.PreparedStatement;
  7 import java.sql.ResultSet;
  8 import java.sql.SQLException;
  9 import java.text.SimpleDateFormat;
 10 import java.util.*;
 11 
 12 import javax.servlet.*;
 13 import javax.servlet.http.*;
 14 
 15 /**
 16  * 
 17  * @date 2014-05-23
 18  * @author asif
 19  * 检测用户注册信息是否合法
 20  *
 21  */
 22 
 23 @SuppressWarnings("serial")
 24 public class CheckRegister  extends HttpServlet implements Servlet{
 25     public void doPost(HttpServletRequest request,HttpServletResponse response) throws IOException
 26     {
 27         response.setContentType("Text/html;charset=GB2312");
 28         request.setCharacterEncoding("GB2312");
 29         String name = request.getParameter("username1");
 30         String passwd1 = request.getParameter("password1");
 31         String passwd2 = request.getParameter("password2");
 32         int totlogin = 0;
 33         //获得输出流
 34         PrintWriter out = response.getWriter();
 35         if(name.trim().equals(""))
 36         {
 37             out.println("<html>");
 38             out.println("<head>");
 39             out.println("<meta http-equiv="Refresh" content="2;url= login.jsp">");
 40             out.println("<title>Wait 2s</title>");
 41             out.println("</head>");
 42             out.println("<body>用户名不能为空</body>");
 43             out.println("</html>");
 44         }
 45         else if(!passwd1.equals(passwd2))
 46         {
 47             out.println("<html>");
 48             out.println("<head>");
 49             out.println("<meta http-equiv="Refresh" content="2;url= register.jsp">");
 50             out.println("<title>Wait 2s</title>");
 51             out.println("</head>");
 52             out.println("<body>两次密码不一样，请重新注册</body>");
 53             out.println("</html>");
 54         }
 55         else
 56         {
 57             //连接数据库查看用户名是否存在和其密码是否正确
 58             Connection conn = MysqlConnection();
 59             PreparedStatement pstmt = null;
 60             ResultSet rset = null;
 61             String sql = "select * from user where username=?";
 62             try {
 63                 pstmt = conn.prepareStatement(sql);
 64                 pstmt.setString(1, name);
 65                 rset = pstmt.executeQuery();
 66             } catch (SQLException e1) {
 67                 // TODO Auto-generated catch block
 68                 e1.printStackTrace();
 69             }
 70             try {
 71                 if(!rset.next())
 72                 {
 73                     sql = "insert user(username,password,totlogin,date) values(?,?,?,?)";
 74                     pstmt = conn.prepareStatement(sql);
 75                     try {
 76                         pstmt.setString(1, name);
 77                         pstmt.setString(2, passwd1);
 78                         pstmt.setInt(3, totlogin);
 79                         Date now = new Date();
 80                         SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
 81                         String strdate = dateFormat.format(now);
 82                         pstmt.setString(4, strdate);
 83                         pstmt.executeUpdate();
 84                     } catch (SQLException e) {
 85                         // TODO Auto-generated catch block
 86                         e.printStackTrace();
 87                     }
 88                     //关闭数据库
 89                     conn.close();
 90                     out.println("<html>");
 91                     out.println("<head>");
 92                     out.println("<meta http-equiv="Refresh" content="1;url= login.jsp">");
 93                     out.println("<title>Wait 1s</title>");
 94                     out.println("</head>");
 95                     out.println("<body>恭喜您注册成功，马上为您跳转到登陆页面</body>");
 96                     out.println("</html>");
 97                 }
 98                 else
 99                 {
100                     out.println("<html>");
101                     out.println("<head>");
102                     out.println("<meta http-equiv="Refresh" content="2;url= register.jsp">");
103                     out.println("<title>Wait 2s</title>");
104                     out.println("</head>");
105                     out.println("<body>亲，用户名已存在，您还是换一个进行注册吧</body>");
106                     out.println("</html>");
107                 }
108             } catch (SQLException e) {
109                 // TODO Auto-generated catch block
110                 e.printStackTrace();
111             }
112         }
113     }
114     
115     //连接数据库函数
116     public static Connection MysqlConnection()
117     {
118         String username = "root";
119         String userpasswd = "123456";
120         String url = "jdbc:mysql://127.0.0.1:3306/test";
121         try
122         {
123             Class.forName("com.mysql.jdbc.Driver").newInstance();
124             try
125             {
126                 Connection contemp = DriverManager.getConnection(url, username, userpasswd);
127                 return contemp;
128             }
129             catch (SQLException e)
130             {
131                 // TODO Auto-generated catch block
132                 e.printStackTrace();
133             }
134         }
135         catch (InstantiationException e)
136         {
137             // TODO Auto-generated catch block
138             e.printStackTrace();
139         }
140         catch (ClassNotFoundException e) {
141             // TODO Auto-generated catch block
142             e.printStackTrace();
143         } catch (IllegalAccessException e1) {
144             // TODO Auto-generated catch block
145             e1.printStackTrace();
146         }
147         return null;
148     }
149 }
    View Code

    login.jsp

     1 <!--
 2 /**
 3  * 
 4  * @date 2014-05-21
 5  * @author asif
 6  * @login
 7  * 
 8  *
 9  /-->
10 
11 <%@ page contentType="text/html;charset=gb2312" language="java" %>
12 <%@ page import="java.sql.*" %>
13 <%@ page import="java.util.*" %>
14 
15 <html>
16 
17 <head>
18     <title>Login</title>
19 </head>
20 
21 <body>
22     <table height="62%" width="100%">
23     <td align="center" valign="middle">
24         <div align="center">
25             <form method="post" action="login">
26             <image src="./image/logo.gif">
27             <br></br>
28             Username: <input type="text" name="username"><br>
29             Password: <input type="password" name="pwd"><br>
30             <br>
31             <input type="submit" name="submit" value="submit">&nbsp;
32             <input type="reset" name="reset" value="reset">&nbsp;
33             <input type="button" onClick="window.location.href='register.jsp'" value="register">
34             </form>
35         </div>
36     </td>
37     </table>
38 </body>
39 
40 </html>
    View Code

    register.jsp

     1 <%@ page language="java" contentType="text/html; charset=ISO-8859-1"
 2     pageEncoding="ISO-8859-1"%>
 3 
 4 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 5 <html>
 6 <head>
 7 <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
 8 <title>register</title>
 9 </head>
10 
11 <body>
12     <form action="register" method=post>
13     <table align="center">
14     <tr></tr><tr></tr><tr></tr><tr></tr><tr></tr><tr></tr><tr></tr>
15     <tr></tr><tr></tr><tr></tr><tr></tr><tr></tr><tr></tr><tr></tr>
16     <tr></tr><tr></tr><tr></tr><tr></tr><tr></tr><tr></tr><tr></tr>
17     <tr></tr><tr></tr><tr></tr><tr></tr><tr></tr><tr></tr><tr></tr>
18     <tr></tr><tr></tr><tr></tr><tr></tr><tr></tr><tr></tr><tr></tr>
19     <tr></tr><tr></tr><tr></tr><tr></tr><tr></tr><tr></tr><tr></tr>
20     <tr></tr><tr></tr><tr></tr><tr></tr><tr></tr><tr></tr><tr></tr>
21     <tr></tr><tr></tr><tr></tr><tr></tr><tr></tr><tr></tr><tr></tr>
22     <tr></tr><tr></tr><tr></tr><tr></tr><tr></tr><tr></tr><tr></tr>
23     <tr></tr><tr></tr><tr></tr><tr></tr><tr></tr><tr></tr><tr></tr>
24         <tr><td align="center"><font size=2>Username: </font></td>
25         <td><Input type="text" name="username1"></td>
26         </tr><tr></tr>
27         <tr><td align="center"><font size=2>Password: </font></td>
28         <td><Input type="password" name="password1"></td>
29         </tr><tr></tr>
30         <tr><td align="center"><font size=2>Comfirepassword: </font></td>
31         <td><Input type="password" name="password2"></td>
32         </tr><tr></tr>
33     </table>
34     <br>
35     <div align="center">
36         <Input type="submit" name="reg" value="register">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
37         <Input type="reset" name="reset" value="reset">
38     </div>
39     </form>
40 </body>
41 
42 </html>
    View Code

    web.xml　　　　//这个很重要，路径绝对不能错

     1 <?xml version="1.0" encoding="UTF-8"?>
 2 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
 3   <display-name>ServletTest</display-name>
 4   <welcome-file-list>
 5     <welcome-file>login.jsp</welcome-file>
 6   </welcome-file-list>
 7   
 8   <servlet>
 9     <servlet-name>login</servlet-name>
10     <servlet-class>com.wyd.www.CheckUser</servlet-class>
11   </servlet>
12   
13     <servlet>
14     <servlet-name>register</servlet-name>
15     <servlet-class>com.yqr.www.CheckRegister</servlet-class>
16   </servlet>
17   
18   <servlet-mapping>
19     <servlet-name>login</servlet-name>
20     <url-pattern>/login</url-pattern>
21   </servlet-mapping>
22   
23     <servlet-mapping>
24     <servlet-name>register</servlet-name>
25     <url-pattern>/register</url-pattern>
26   </servlet-mapping>
27 
28 
29 </web-app>
    View Code

    本来想用一个User类记录用户的，后面写着写着没用到······稍微修改一下CheckUser.java应该就可以去掉 

    个人感觉JSP和servlet的表面差别就是JSP把java程序放到网页文件里面了，而servlet则是分开的~~
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  • 原文地址：https://www.cnblogs.com/asif/p/3747818.html
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