Update

src/finalexam/Database/UserLogin.java

@@ -0,0 +1,66 @@
+package finalexam.Database;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+import java.util.Scanner;
+
+public class UserLogin {
+    static final String DBURL = "jdbc:mysql://localhost:3306/xiaoshou?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=GMT";
+
+    public static void main(String[] args) {
+        Scanner scanner = new Scanner(System.in);
+        Connection conn = null;
+        PreparedStatement pstmt = null;
+        ResultSet rs = null;
+        try {
+            Class.forName("com.mysql.cj.jdbc.Driver");
+            conn = DriverManager.getConnection(DBURL);
+            int attempts = 0;
+            boolean loginSuccess = false;
+            while (attempts < 3 && !loginSuccess) {
+                System.out.println("欢迎使用阳光超市收银系统，请登陆");
+                System.out.print("请输入用户名: ");
+                String username = scanner.nextLine();
+                System.out.print("请输入密码: ");
+                String password = scanner.nextLine();
+                String sql = "SELECT xingming FROM t_yong WHERE yonghuming=? AND mima=?";
+                pstmt = conn.prepareStatement(sql);
+                pstmt.setString(1, username);
+                pstmt.setString(2, Encrypt.MD5(password));
+                rs = pstmt.executeQuery();
+                if (rs.next()) {
+                    loginSuccess = true;
+                    String xingming = rs.getString("xingming");
+                    SimpleDateFormat formatter = new SimpleDateFormat("yyyy年MM月dd日HH时mm分ss秒");
+                    String currentTime = formatter.format(new Date());
+                    System.out.println("欢迎使用阳光超市收银系统");
+                    System.out.println("当前收银员：" + xingming);
+                    System.out.println("当前时间：" + currentTime);
+                } else {
+                    System.out.println("用户名或密码不正确，请重新输入");
+                    attempts++;
+                }
+            }
+            if (!loginSuccess)
+                System.out.println("最多只能尝试3次");
+        } catch (Exception e) {
+            e.printStackTrace();
+        } finally {
+            try {
+                if (rs != null)
+                    rs.close();
+                if (pstmt != null)
+                    pstmt.close();
+                if (conn != null)
+                    conn.close();
+            } catch (SQLException se) {
+                se.printStackTrace();
+            }
+        }
+    }
+}