连接数据库的5种方式

JDBC 程序编写步骤

1. 注册驱动 - 加载Driver类
2. 获取连接 - 得到Connection
3. 执行增删改查 - 发送SQL给mysql执行
4. 释放资源 - 关闭相关连接

package com.jdbc;

import com.mysql.cj.jdbc.Driver;
import org.junit.jupiter.api.Test;

import java.io.FileInputStream;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;

public class Jdbc02 {
    @Test//方式1
    public void connect01() throws SQLException {
        Driver driver = new Driver();
        String url = "jdbc:mysql://localhost:3306/bd01";
        Properties properties = new Properties();
        properties.setProperty("user", "root");
        properties.setProperty("password", "123456");
        Connection connect = driver.connect(url, properties);
        System.out.println("第一种方法：" + connect);
    }

    @Test//方式2
    public void connect02() throws ClassNotFoundException, IllegalAccessException, InstantiationException, SQLException {
        //使用反射加载 Driver 类 , 动态加载，更加的灵活，减少依赖性
        Class<?> aClass = Class.forName("com.mysql.cj.jdbc.Driver");
        Driver driver = (Driver) aClass.newInstance();
        String url = "jdbc:mysql://localhost:3306/bd01";
        Properties properties = new Properties();
        properties.setProperty("user", "root");
        properties.setProperty("password", "123456");
        Connection connect = driver.connect(url, properties);
        System.out.println("第二种方法：" + connect);
    }

    @Test//方式3
    public void connect03() throws ClassNotFoundException, IllegalAccessException, InstantiationException, SQLException {
        //使用反射加载 Driver 类 , 动态加载，更加的灵活，减少依赖性
        Class<?> aClass = Class.forName("com.mysql.cj.jdbc.Driver");
        Driver driver = (Driver) aClass.newInstance();
        String url = "jdbc:mysql://localhost:3306/bd01";
        String user = "root";
        String password = "123456";
        DriverManager.registerDriver(driver);//注册 Driver 驱动
        Connection connection = DriverManager.getConnection(url, user, password);
        System.out.println("第三种方法：" + connection);
    }

    @Test//方式4  推荐使用
    public void connect04() throws ClassNotFoundException, SQLException {
        Class.forName("com.mysql.cj.jdbc.Driver");
        String url = "jdbc:mysql://localhost:3306/bd01";
        String user = "root";
        String password = "123456";
        Connection connection = DriverManager.getConnection(url, user, password);
        System.out.println("第四种方法：" + connection);
    }

    @Test//方式5
    public void connect05() throws IOException, ClassNotFoundException, SQLException {
        Properties properties = new Properties();
        properties.load(new FileInputStream("src\mysql.properties"));
        String user = properties.getProperty("user");
        String password = properties.getProperty("password");
        String url = properties.getProperty("url");
        String driver = properties.getProperty("driver");
        Class.forName(driver);
        Connection connection = DriverManager.getConnection(url, user, password);
        System.out.println("第五种方式：" + connection);
    }
}

方式5需要配置properties文件

user=root
password=123456
url=jdbc:mysql://localhost:3306/bd01?rewriteBatchedStatements=true
driver=com.mysql.cj.jdbc.Driver

properties配置文件放在src目录下，我的配置文件是mysql.properties