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1.需求和步骤
1）在MySql 数据库中创建users:id ,user,password 。添加记录
2）定义一个login.html ，定义两个字段：user，password 。发送请求到LoginServlet
3）创建一个LoginServlet（继承HttpServlet，重写doPost方法），在其中获取请求的user，password
4) 利用JDBC 从users 中查询有没有和页面输入的user，password 对应的记录。若有，响应hello：xxx，若没有，sorry：xxx ，其中xxx为user
2.代码结构
1）com.jason.testweb.LoginServlet：Servlet类，处理前台提交的数据
1 package com.jason.testweb;
2
3 import java.io.IOException;
4 import java.io.PrintWriter;
5 import java.sql.Connection;
6 import java.sql.PreparedStatement;
7 import java.sql.ResultSet;
8 import java.sql.SQLException;
9
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 import com.jason.util.JDBCUtil;
16
17 public class LoginServlet extends HttpServlet {
18
19 /**
20 *
21 */
22 private static final long serialVersionUID = 2197552322420611512L;
23
24 @Override
25 protected void doPost(HttpServletRequest request,
26 HttpServletResponse response) throws ServletException, IOException {
27
28 String userName = request.getParameter("username");
29 String passWord = request.getParameter("password");
30 PrintWriter printWriter = response.getWriter();
31
32 Connection connection = null;
33 PreparedStatement preparedStatement = null;
34 ResultSet resultSet = null;
35
36 try {
37 connection = JDBCUtil.getConnection();
38 String sql = "SELECT count(id) FROM users WHERE username = ? AND password = ? ";
39 preparedStatement = connection.prepareStatement(sql);
40 preparedStatement.setString(1, userName);
41 preparedStatement.setString(2, passWord);
42
43 resultSet = preparedStatement.executeQuery();
44
45 if (resultSet.next()) {
46 int count = resultSet.getInt(1);
47 if (count > 0) {
48 printWriter.print("hello : " + userName);
49 } else {
50 printWriter.print("sorry : " + userName);
51 }
52 }
53
54 } catch (Exception e) {
55 e.printStackTrace();
56 } finally {
57 JDBCUtil.closeAll(connection, preparedStatement, resultSet);
58 }
59
60 }
61
62 }
2）com.jason.testweb.JDBCUtil：JDBU工具类，获取连接，和关闭资源
1 package com.jason.util;
2
3 import java.sql.Connection;
4 import java.sql.DriverManager;
5 import java.sql.PreparedStatement;
6 import java.sql.ResultSet;
7 import java.sql.SQLException;
8
9 public class JDBCUtil {
10
11 // 获取连接
12 public static Connection getConnection() throws Exception {
13
14 String driverClass = "com.mysql.jdbc.Driver";
15 String JDBCurl = "jdbc:mysql://127.0.0.1:3306/atguigu";
16 String user = "root";
17 String password2 = "zhangzhen";
18 Class.forName(driverClass);
19 return DriverManager.getConnection(JDBCurl, user, password2);
20 }
21
22 // 关闭流
23 public static void closeAll(Connection con, PreparedStatement ps,
24 ResultSet rs) {
25
26 if (rs != null) {
27 try {
28 rs.close();
29 } catch (SQLException e) {
30 // TODO Auto-generated catch block
31 e.printStackTrace();
32 }
33 }
34 if (ps != null) {
35 try {
36 ps.close();
37 } catch (SQLException e) {
38 // TODO Auto-generated catch block
39 e.printStackTrace();
40 }
41 }
42 if (con != null) {
43 try {
44 con.close();
45 } catch (SQLException e) {
46 // TODO Auto-generated catch block
47 e.printStackTrace();
48 }
49 }
50
51 }
52
53 }
3）login.html：显示页面
1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
2 <html>
3 <head>
4 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
5 <title>this is a test </title>
6 </head>
7 <body>
8 <form action="login" method="post">
9
10 user:<input type="text" name="username"/>
11 password:<input type="password" name="password"/>
12
13 <input type="submit" value="submit"/>
14
15 </form>
16 </body>
17 </html>
4)web.xml：配置Servlet 和 映射 Servlet
1 <?xml version="1.0" encoding="UTF-8"?>
2 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
3 xmlns="http://java.sun.com/xml/ns/javaee"
4 xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
5 id="WebApp_ID" version="3.0">
6 <!-- 配置和映射servlet -->
7 <servlet>
8 <servlet-name>LoginServlet</servlet-name>
9 <servlet-class>com.jason.testweb.LoginServlet</servlet-class>
10 </servlet>
11
12 <servlet-mapping>
13 <servlet-name>LoginServlet</servlet-name>
14 <url-pattern>/login</url-pattern> <!-- 和提表单提交的 action 一致 -->
15 </servlet-mapping>
16
17 </web-app>
3.总结分析
1）本实验只是模拟了一次完整的由 view -> control -> model
2) 本实验未使用连接池：c3p0
3）缺少模块化设计