后台登录系统，JDBC连接数据库，做小案例练习

巩固自己的基础，以后学习框架学起来也可以称心应手一些，案例很简单，重要的是巩固自己的学习。

作为第一个类，把他们联系起来

package Web.JDBClogin;

import java.util.Scanner;

public class procedure {
    public  void gui() throws Exception {

        Scanner scanner = new Scanner(System.in);
        System.out.println("应用程序");
        System.out.println("1.登录账号");
        System.out.println("2.注册账号");
        System.out.println("3.退出");
        String serialnumber = scanner.nextLine();
        switch (serialnumber) {
            case "1":
                new Login().login();
                break;
            case "2":
                new Enroll().enroll();
                break;
            case "3":
                System.out.println("退出成功 祝你 生活愉快!~ ");
                break;
        }

    }
}

通过switch来实现登录方法，注册方法也同路理

package Web.JDBClogin;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.Scanner;

/**
* 登录
*/
public class Login {
    public  void login() throws Exception {

        Scanner sc = new Scanner(System.in);
        System.out.println("请输入账号：");
        String userName = sc.nextLine();
        System.out.println("请输入密码：");
        String password = sc.nextLine();

        Connection connection1 = JdbcConnection.getCon();
        String sql = "select * from tb_user where username=? and password=?";

        PreparedStatement pst = connection1.prepareStatement(sql);

        pst.setString(1, userName);
        pst.setString(2, password);

        ResultSet rs = pst.executeQuery();

        if (rs.next()) {
            System.out.println("恭喜" + userName + "登录成功");
        } else {
            System.out.println("账号或密码错误或不存在");

        }
    }
}

注册功能实现

package Web.JDBClogin;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.util.Scanner;

/**
* 注册
*/
public class Enroll {
    public  void enroll() throws Exception {

        Scanner sc1 = new Scanner(System.in);
        System.out.println("请输入注册账号");
        String Raa = sc1.nextLine();
        System.out.println("请输入注册密码");
        String Rp = sc1.nextLine();

        Connection connection = JdbcConnection.getCon();

        String sql = "insert into tb_user (username,password) values ( ? ,? )";
        //执行sql
        PreparedStatement pst = connection.prepareStatement(sql);
        pst.setString(1, Raa);
        pst.setString(2, Rp);
        int exdate = pst.executeUpdate();

        if (exdate != 0) {
            System.out.println("注册成功");
            System.out.println("重新登录.....");
            new Login().login(); //注册成功 会再一次进行登录 代码完善
        } else {
            System.out.println("注册失败");
        }
    }
}

数据库连接 

URL,username,password,手动填写，forName反射连接

package Web.JDBClogin;

import java.sql.*;

/**
* 数据库连接
*/
public class JdbcConnection {
    private static final String url = 
    private static final   String username = ;
    private static final String password = ;
    private static final String jdbcName = "com.mysql.jdbc.Driver";

    static {
        try {
            Class.forName(jdbcName);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    public static Connection getCon() {
        Connection con;//作用域
        try {
            con = DriverManager.getConnection(url, username, password);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
        return con;
    }

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

main方法

procedure procedure = new procedure();
procedure.gui();

 

简单的登录系统案例就做完了。

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