9.27

[实验任务二]：单一职责原则

登录模块在实际项目开发中很常见，请按照教材28页（PPT49页）利用单一职责原则重构后的类图实现这一模块。

实验要求：

1.提交源代码和对应的数据库文件（注意将此模块保存，以备以后使用）；

2.注意编程规范。

 

代码：

DBUtil.java

package Test;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class DBUtil {

   public static String db_url = "jdbc:mysql://localhost:3306/first?serverTimezone=GMT%2B8&useSSL=false";
   public static String db_user = "root";
   public static String db_pass = "ydt041113";

   public static Connection getConn () {
       Connection conn = null;

       try {
           Class.forName("com.mysql.cj.jdbc.Driver");
           conn = DriverManager.getConnection(db_url, db_user, db_pass);
       } catch (Exception e) {
           e.printStackTrace();
       }

       return conn;
   }//end getConn

   public static void close (Statement state, Connection conn) {
       if (state != null) {
           try {
               state.close();
           } catch (SQLException e) {
               e.printStackTrace();
           }
       }

       if (conn != null) {
           try {
               conn.close();
           } catch (SQLException e) {
               e.printStackTrace();
           }
       }
   }

   public static void close (ResultSet rs, Statement state, Connection conn) {
       if (rs != null) {
           try {
               rs.close();
           } catch (SQLException e) {
               e.printStackTrace();
           }
       }

       if (state != null) {
           try {
               state.close();
           } catch (SQLException e) {
               e.printStackTrace();
           }
       }

       if (conn != null) {
           try {
               conn.close();
           } catch (SQLException e) {
               e.printStackTrace();
           }
       }
   }

   public static void main(String[] args) throws SQLException {
       Connection conn = getConn();
       PreparedStatement pstmt = null;
       ResultSet rs = null;
       String sql ="select * from user";
       pstmt = conn.prepareStatement(sql);
       rs = pstmt.executeQuery();
       if(rs.next()){
           System.out.println("连接成功");
       }else{
           System.out.println("连接失败");
       }
   }
}

LoginForm.java

package Test;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class LoginForm extends JFrame {

   private static final long serialVersionUID = 1L;
   private  UserDao dao = new UserDao();
   //设置按钮组件

   private  JButton jb=new JButton("登录");  //添加一个登录按钮
   private JButton button=new JButton("重置");   //添加一个确定按钮
   //设置文本框组件
   private JTextField username = new JTextField();//用户名框
   private JPasswordField password = new JPasswordField();//密码框：为加密的***

   JLabel user_name=new JLabel("账号：");//设置左侧用户名文字
   JLabel pass_word=new JLabel("密码：");//设置左侧密码文字

   public void init()
   {
       /* 组件绝对位置  */
       user_name.setBounds(50, 70, 300, 25);
       pass_word.setBounds(50, 130, 200, 25);

       username.setBounds(110, 70, 300, 25);//设置用户名框的宽，高，x值，y值
       password.setBounds(110, 130, 300, 25);//设置密码框的宽，高，x值，y值

       button.setBounds(315, 225, 90, 20);//设置确定按钮的宽，高，x值，y值
       jb.setBounds(95, 225, 90, 20);//设置确定按钮的宽，高，x值，y值


       /* 组件透明化*/
       user_name.setOpaque(false);
       pass_word.setOpaque(false);


       //监听事件
       jb.addActionListener(new ActionListener(){     //为确定按钮添加监听事件

           @SuppressWarnings("deprecation")
           public void actionPerformed(ActionEvent arg0) {
               validate(username.getText().trim(),password.getText().trim());
           }
       });


       //重置按钮
       button.addActionListener(new ActionListener(){     //为重置按钮添加监听事件
           //同时清空name、password的数据
           public void actionPerformed(ActionEvent arg0) {
               // TODO 自动生成方法存根
               username.setText("");
               password.setText("");
           }
       });

   }

   public void display()
   {
       JFrame f =new JFrame();
       f.setTitle("登录页面");
       //窗口退出行为
       f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       //设置窗口大小不可变
       f.setResizable(false);
       //设置窗口打开居中
       f.setLocationRelativeTo(null);
       //窗口大小
       f.setSize(500, 300);

       init();

       //添加组件
       Container contentPanel= new Container();//添加一个contentPanel容器
       contentPanel.setLayout(null);//设置添加的contentPanel容器为流布局管理器
       contentPanel.add(user_name);
       contentPanel.add(pass_word);
       contentPanel.add(username);
       contentPanel.add(password);
       contentPanel.add(jb);
       contentPanel.add(button);

       f.add(contentPanel);
       //展示窗口
       f.setVisible(true);
   }


   public  void  validate(String username,String password)
   {

       if(username.trim().length()==0||password.trim().length()==0){
           JOptionPane.showMessageDialog(null, "用户名,密码不允许为空");

           return;
       }

       if(dao.findUser(username, password))
       {

           JOptionPane.showMessageDialog(null, "登录成功！");


       }else {
           JOptionPane.showMessageDialog(null, "用户名或密码错误");

       }

   }

}

MainClass.java

package Test;

public class MainClass {

   public static void main(String[] args)
   {
       LoginForm loginForm=new LoginForm() ;   //调用
       loginForm.display();

   }

}

UserDao.java

package Test;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class UserDao {
   private Test.DBUtil DBUtil;

   public boolean findUser(String username, String password) {
       //准备SQL语句
       String sql = "select * from user where username ='" + username + "'";
       Connection conn= DBUtil.getConn();
       //创建语句传输对象
       Statement state = null;
       ResultSet rs= null;
       int flag=0;
       String c_password=null;
       try {
           state = conn.createStatement();
           rs = state.executeQuery(sql);
           while(rs.next()) {
               ++flag;
               c_password=rs.getString("password");
           }   if (flag == 0) {
               return false;
           }
           if (!password.equals(c_password)) {   //判断密码
               return false;
           }
       }catch (SQLException e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
       }finally {
           DBUtil.close(rs, state, conn);
       }
       return true;
   }
}

数据库代码：

/*

 Navicat Premium Data Transfer

 

 Source Server         : ss

 Source Server Type    : MySQL

 Source Server Version : 80034

 Source Host           : localhost:3306

 Source Schema         : first

 

 Target Server Type    : MySQL

 Target Server Version : 80034

 File Encoding         : 65001

 

 Date: 30/09/2024 09:24:20

*/

 

SET NAMES utf8mb4;

SET FOREIGN_KEY_CHECKS = 0;

 

-- ----------------------------

-- Table structure for user

-- ----------------------------

DROP TABLE IF EXISTS `user`;

CREATE TABLE `user`  (

  `id` int NOT NULL AUTO_INCREMENT,

  `username` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL,

  `password` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL,

  PRIMARY KEY (`id`) USING BTREE

) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_0900_ai_ci ROW_FORMAT = Dynamic;

 

-- ----------------------------

-- Records of user

-- ----------------------------

INSERT INTO `user` VALUES (1, '1', '1');

 

SET FOREIGN_KEY_CHECKS = 1;

运行截图：