Login the system in the background, connect the database with JDBC, and do small case exercises

Consolidate your foundation , In the future, the learning framework can also be handy , The case is very simple , The important thing is to consolidate your study .

As the first class , Connect them

package Web.JDBClogin;

import java.util.Scanner;

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

        Scanner scanner = new Scanner(System.in);
        System.out.println(" Applications ");
        System.out.println("1. Login account ");
        System.out.println("2. Registered account ");
        System.out.println("3. sign out ");
        String serialnumber = scanner.nextLine();
        switch (serialnumber) {
            case "1":
                new Login().login();
                break;
            case "2":
                new Enroll().enroll();
                break;
            case "3":
                System.out.println(" Quit successfully I wish you Life is happy !~ ");
                break;
        }

    }
}

adopt switch To implement the login method , The registration method is the same

package Web.JDBClogin;

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

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

        Scanner sc = new Scanner(System.in);
        System.out.println(" Please enter your account number ：");
        String userName = sc.nextLine();
        System.out.println(" Please input a password ：");
        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(" Congratulations " + userName + " Login successful ");
        } else {
            System.out.println(" The account or password is wrong or does not exist ");

        }
    }
}

Registration function

package Web.JDBClogin;

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

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

        Scanner sc1 = new Scanner(System.in);
        System.out.println(" Please enter your account number ");
        String Raa = sc1.nextLine();
        System.out.println(" Please enter the registration password ");
        String Rp = sc1.nextLine();

        Connection connection = JdbcConnection.getCon();

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

        if (exdate != 0) {
            System.out.println(" Registered successfully ");
            System.out.println(" Log back in .....");
            new Login().login(); // Registered successfully Will log in again Code perfect
        } else {
            System.out.println(" Registration failed ");
        }
    }
}

Database connection  

URL,username,password, Fill in by hand ,forName Reflection connection

package Web.JDBClogin;

import java.sql.*;

/**
* Database connection
*/
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;// Scope
        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 Method

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

 

The simple login system case is finished .

A great bai .