IDEA使用JDBC连接MYSQL库

2022-02-23 19:03:50

在MYSQL学习过程中，我们可以使用IDEA来连接MSYQL库，对MSYQL库进行操作，这里需要用到JDBC
我使用的版本是 mysql-connector-java-5.1.17，可以根据自己的mysql版本进行调整
可以进入MAVEN仓库 https://mvnrepository.com/ 搜索MySQL

选择自己需要的版本

下载完成之后使用IDEA导入jar包，因为IDEA版本不同这个Project Structure可能在IDEA界面右边的小齿轮

打开之后导入你的JAR包，导入后需要点击一下APPLY，否则可能不会显示。

这样便是成功导入，下面来建立连接。

mysqltestDemo

import java.sql.*;

public class mysqltestdemo {
    public static void main(String[] args) throws Exception {
//     JDBC的使用
//        1.通过反射加在 加载驱动
         Class.forName("com.mysql.jdbc.Driver");
//        2.建立连接
        Connection connection = DriverManager.getConnection("jdbc:mysql://master:3306/shujia", 
                                                            "root", "123456");
//        3.创建执行器,用来执行SQL语句
//          1.createStatement()
//            2.prepareStatement()
        Statement statement = connection.createStatement();
        String sql ="select * from student";
//        4.执行SQL语句
        ResultSet rs = statement.executeQuery(sql);
//        5.获取结果
        System.out.println(rs);
//        6.关闭
        rs.close();
        statement.close();
        connection.close();
    }

import java.sql.*;

public class mysqltestdemo {
    public static void main(String[] args) throws Exception {
//     JDBC的使用
//        1.通过反射加在 加载驱动
        Class.forName("com.mysql.jdbc.Driver");
//        2.建立连接
        Connection connection = DriverManager.getConnection("jdbc:mysql://master:3306/shujia",
                "root", "123456");
//        3.创建执行器,用来执行SQL语句
//          1.createStatement()
//            2.prepareStatement()
        Statement statement = connection.createStatement();
        String sql ="select * from student";
//        4.执行SQL语句
        ResultSet rs = statement.executeQuery(sql);
//        5.获取结果
        while(rs.next()){
            System.out.println(rs.getInt("id"));
            System.out.println(rs.getString("name"));
            System.out.println(rs.getInt("sex"));
            System.out.println(rs.getString("age"));
        }
//        6.关闭
        rs.close();
        statement.close();
        connection.close();
    }
}

mysqlInsert

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
import java.util.Scanner;

public class mysqlnsert {
    public static void main(String[] args) throws Exception {

        Scanner scanner = new Scanner(System.in);
        String name = scanner.next();
        int age=scanner.nextInt();
        String sex=scanner.next();

        Class.forName("com.mysql.jdbc.Driver");
        Connection connection = DriverManager.getConnection("jdbc:mysql://master:3306/shujia",
                "root", "123456");
        Statement statement = connection.createStatement();

        String sql="insert into student(name,age,sex) values(\""+name+"\","+age+",\""+sex+"\")";
        int i = statement.executeUpdate(sql);
        System.out.println(i);
        if(i==1){
            System.out.println("注册成功");
        }else{
            System.out.println("注册失败");
        }
        statement.close();
        connection.close();
    }
}

mysqlDelete

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;

public class mysqlDelete {
    public static void main(String[] args) throws Exception {
        Class.forName("com.mysql.jdbc.Driver");
        Connection connection = DriverManager.getConnection("jdbc:mysql://master:3306/shujia",
                "root", "123456");
        Statement statement = connection.createStatement();
        String sql="delete from student where name=‘zhontg‘";
        int i = statement.executeUpdate(sql);
        System.out.println(i);
        statement.close();
        connection.close();
    }
}

msyqlUpdate

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;

public class mysqlDelete {
    public static void main(String[] args) throws Exception {
        Class.forName("com.mysql.jdbc.Driver");
        Connection connection = DriverManager.getConnection("jdbc:mysql://master:3306/shujia",
                "root", "123456");
        Statement statement = connection.createStatement();
        String sql="delete from student where name=‘zhontg‘";
        int i = statement.executeUpdate(sql);
        System.out.println(i);
        statement.close();
        connection.close();
    }
}

Login01

package mysql.statement;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.Scanner;

public class Login01 {
    public static void main(String[] args) throws  Exception {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入用户：");
        String username = scanner.next();
        System.out.println("请输入密码：");
        String password = scanner.next();

        Class.forName("com.mysql.jdbc.Driver");
        Connection connection = DriverManager.getConnection("jdbc:mysql://master:3306/shujia",
                "root", "123456");
        Statement statement = connection.createStatement();
//      1.通过username去mysql中查找有没有这一条记录(存在：输入密码，不存在：报错)
//      2.存在之后，用查到的密码匹配输入的密码
        String sql="select * from user where username=‘"+username+"‘";
        ResultSet rs = statement.executeQuery(sql);
        if(!rs.next()){
            System.out.println("用户输出错误");
//            结束
        }
//        匹配密码
        String password1 = rs.getString("password");
        if(password==null || !password.equals(password1)){
            System.out.println("密码不匹配失败");
        }else {
            System.out.println("登陆成功");
        }
        rs.close();
        statement.close();
        connection.close();
    }
}

注意：这里使用 createStatement 之后，在使用 123‘ or ‘1=1时会直接登录成功，这是因为产生了sql注入
sql注入：参数传递时，参数中的内容当做关键字来使用
优化：使用prepareStatement来进行

package mysql.statement;

import java.sql.*;
import java.util.Scanner;

public class Login02 {
    public static void main(String[] args) throws  Exception {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入用户：");
        String username = scanner.nextLine();
        System.out.println("请输入密码：");
        String password = scanner.next();

        Class.forName("com.mysql.jdbc.Driver");
        Connection connection = DriverManager.getConnection("jdbc:mysql://master:3306/shujia",
                "root", "123456");
        String sql="select * from user where username=?";
        PreparedStatement statement = connection.prepareStatement(sql);
        statement.setString(1,username);
//      1.通过username去mysql中查找有没有这一条记录(存在：输入密码，不存在：报错)
//      2.存在之后，用查到的密码匹配输入的密码
        ResultSet rs = statement.executeQuery();
        if(!rs.next()){
            System.out.println("用户输出错误");
//            结束
        }
//        匹配密码
        String password1 = rs.getString("password");
        if(password==null || !password.equals(password1)){
            System.out.println("密码不匹配失败");
        }else {
            System.out.println("登陆成功");
        }
        rs.close();
        statement.close();
        connection.close();
    }
}

IDEA使用JDBC连接MYSQL库

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