servlet增删查改demo（一）注册与登录

项目结构

增删查改利用jsp前端页面获取用户在浏览器输入或者操作的数据，利用servlet进行处理，通过jdbc调用数据库，从而完成用户的要求。

　　userregister.jsp

 1 <%@ page language="java" contentType="text/html; charset=utf-8"
 2     pageEncoding="utf-8"%>
 3 <!DOCTYPE html>
 4 <html>
 5 <head>
 6 <meta charset="utf-8">
 7 <title>用户注册</title>
 8 </head>
 9 <body>
10     
11     <form action="userregister" method="post">
12             <table align = "center" border="1" style="border-collapse: collapse;">
13                 <tr>
14                     <td colspan="2">用户注册</td>
15                 </tr>
16                 <tr>
17                     <td>用户名：</td>
18                     <td><input type="text" name="userName" /></td>
19                 </tr>
20                 <tr>
21                     <td>密码：</td>
22                     <td><input type="password" name="userPassword" /></td>
23                 </tr>
24                 <tr>
25                     <td class="tdstyle" colspan="2">
26                         <input type="submit" value="注册" />
27                     </td>
28                 </tr>
29             </table>
30     </form>    
31     
32 </body>
33 </html>

userlogin.jsp

 1 <%@ page language="java" contentType="text/html; charset=utf-8"
 2     pageEncoding="utf-8"%>
 3 <!DOCTYPE html>
 4 <html>
 5 <head>
 6 <meta charset="ISO-8859-1">
 7 <title>登录页面</title>
 8 </head>
 9 <body>
10 
11      <form action="login" method="post">
12           <p>用户名: <input type="text" name="username" /></p>
13           <p>密&nbsp;&nbsp;&nbsp;&nbsp;码: <input type="password" name="password" /></p>
14           <input type = "submit" name="login" value ="登录"/>
15       </form>
16 
17 </body>
18 </html>

ServletUserRegister.java

 1 package servlet;
 2 
 3 import java.io.IOException;
 4 import java.sql.SQLException;
 5 
 6 import javax.servlet.ServletException;
 7 import javax.servlet.http.HttpServlet;
 8 import javax.servlet.http.HttpServletRequest;
 9 import javax.servlet.http.HttpServletResponse;
10 
11 import dao.UserDao;
12 import vo.UserEmp;
13 
14 public class ServletUserRegister extends HttpServlet{
15 
16     public void doPost(HttpServletRequest request,HttpServletResponse response) throws IOException, ServletException {
17         
18         request.setCharacterEncoding("utf8");
19         response.setCharacterEncoding("utf8");
20         
21         //获取表单中的username，password
22         String username = request.getParameter("userName");
23         String password = request.getParameter("userPassword");
24         
25         //数据存入VO
26         UserEmp useremp = new UserEmp();
27         useremp.setUsername(username);
28         useremp.setPassword(password);
29         
30         //实例化操作数据库对象
31         UserDao userDao = new UserDao();
32         //调用增加用户方法
33         try {
34             userDao.insert(useremp);
35         } catch (SQLException e) {
36             e.printStackTrace();
37         }
38         
39         request.getRequestDispatcher("/userlogin.jsp").forward(request, response);
40         
41     }
42     
43 }

从表单中获取用户输入的数据，存储到数据库中，在把页面转发到登录页面。

ServletUserLogin.java

 1 package servlet;
 2 
 3 import java.io.IOException;
 4 import java.sql.SQLException;
 5 
 6 import javax.servlet.ServletException;
 7 import javax.servlet.http.HttpServlet;
 8 import javax.servlet.http.HttpServletRequest;
 9 import javax.servlet.http.HttpServletResponse;
10 
11 import dao.UserDao;
12 import vo.UserEmp;
13 
14 public class ServletUserLogin extends HttpServlet {
15     
16     @Override
17     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException {
18         
19         req.setCharacterEncoding("utf8");
20         resp.setCharacterEncoding("utf8");
21         
22         String username = req.getParameter("username");
23         String password = req.getParameter("password");
24         
25         UserEmp userEmp = new UserEmp();
26         userEmp.setUsername(username);
27         userEmp.setPassword(password);
28         
29         UserDao dao = new UserDao();
30         
31         boolean flag = false;
32         try {
33             flag = dao.login(userEmp);
34         } catch (SQLException e) {
35             e.printStackTrace();
36         }
37         
38         if(flag)
39             req.getRequestDispatcher("/userlist.jsp").forward(req, resp);
40         else
41             req.getRequestDispatcher("/userlogin.jsp").forward(req, resp);
42         
43     }
44     
45 }

从浏览器获取用户输入数据，与底层数据库的数据比较，若用户名密码都相等则页面转到list页面，若不同则重新刷新当前登录页面

UserDao.java

 1 package dao;
 2 
 3 import java.sql.Connection;
 4 import java.sql.PreparedStatement;
 5 import java.sql.ResultSet;
 6 import java.sql.SQLException;
 7 import java.sql.Statement;
 8 
 9 import vo.UserEmp;
10 
11 public class UserDao {
12 
13     public boolean login(UserEmp userEmp) throws SQLException {
14         
15         Connection connection = dbmanage.Util.getConnection();
16         Statement statement = connection.createStatement();
17         
18         String sql = "SELECT user_name,user_pawd FROM user_emp ";
19         ResultSet rs = statement.executeQuery(sql);
20         
21         String username = null;
22         String password = null;
23         
24         while(rs.next()) {
25             username = rs.getString("user_name");
26             password = rs.getString("user_pawd");
27             
28             if(username.equals(userEmp.getUsername()) && password.equals(userEmp.getPassword())) {
29                 return true;
30             }
31             
32         }
33         
34         dbmanage.Util.closeDB(statement, connection, rs);
35         
36         return false;
37     }
38     
39     public void delete(UserEmp userEmp) {
40         
41     }
42     
43     public void update(UserEmp userEmp) {
44         
45     }
46     
47     public void insert(UserEmp userEmp) throws SQLException {
48         
49         Connection connection = dbmanage.Util.getConnection();
50         
51         String sql = "INSERT INTO user_emp (user_name,user_pawd) VALUES(?,?)";
52         
53         PreparedStatement ps = connection.prepareStatement(sql);
54         ps.setString(1, userEmp.getUsername());
55         ps.setString(2, userEmp.getPassword());
56         
57         ps.executeUpdate();
58         
59         dbmanage.Util.closeDB(ps, connection);
60         
61     }
62     
63 }

工具类：调用数据库

Util.java

 1 package dbmanage;
 2 
 3 import java.sql.Connection;
 4 import java.sql.DriverManager;
 5 import java.sql.ResultSet;
 6 import java.sql.SQLException;
 7 import java.sql.Statement;
 8 
 9 public class Util {
10 
11     private static String driver = "com.mysql.jdbc.Driver";
12     private static String url = "jdbc:mysql://localhost:3306/my_db?charaterEncoding=utf-8";
13     private static String username = "root";
14     private static String password = "123456";
15     
16     public static Connection getConnection() throws SQLException {
17         
18         Connection con = null;
19         
20         try {
21             Class.forName(driver);
22             con = DriverManager.getConnection(url, username, password);
23         } catch (ClassNotFoundException e) {
24             e.printStackTrace();
25         }
26         
27         return con;
28         
29     }
30     
31     public static void closeDB(Statement statement,Connection connection,ResultSet resultSet) {
32         try {
33             statement.close();
34             resultSet.close();
35             connection.close();
36         } catch (SQLException e) {
37             e.printStackTrace();
38         }
39     }
40     
41     public static void closeDB(Statement statement,Connection connection) {
42         try {
43             statement.close();
44             connection.close();
45         } catch (SQLException e) {
46             e.printStackTrace();
47         }
48     }
49     
50 }

vo：与数据库表对应，通过创建对象把数据存入

UserEmp.java

 1 package vo;
 2 
 3 public class UserEmp {
 4     
 5     private String username;
 6     private String password;
 7     
 8     public String getUsername() {
 9         return username;
10     }
11     public void setUsername(String username) {
12         this.username = username;
13     }
14     public String getPassword() {
15         return password;
16     }
17     public void setPassword(String password) {
18         this.password = password;
19     } 
20     
21 }

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       
 8       <!-- 登录 -->
 9       <servlet>
10           <servlet-name>UserLogin</servlet-name>
11           <servlet-class>servlet.ServletUserLogin</servlet-class>
12       </servlet>
13       <servlet-mapping>
14           <servlet-name>UserLogin</servlet-name>
15           <url-pattern>/login</url-pattern>
16       </servlet-mapping>
17       
18       <!-- 注册 -->
19     <servlet>
20         <servlet-name>UserRegister</servlet-name>
21           <servlet-class>servlet.ServletUserRegister</servlet-class>
22     </servlet>
23     <servlet-mapping>
24           <servlet-name>UserRegister</servlet-name>
25         <url-pattern>/userregister</url-pattern>
26  </servlet-mapping>
27         
28 </web-app>

项目测试：在浏览器地址栏输入项目下的jsp文件即可访问