【JDBC】1.手动获取连接

sun公司提供的一套api(java.sql,javax.sql)，
使用这套api可以实现对数据的连接和操作(DML、DDL)

要想获取连接，准备工作：
① mysql服务开启
② 连接的基本条件：指名数据库的ip地址、端口号、用户名、密码
③ 导入mysql的驱动（即为jdbc中相关接口的实现类的集合）

添加mysql驱动

方式1-方式4逐步优化；会写方式4。

package com.atguigu.java1;

import org.junit.Test;

import java.io.InputStream;
import java.sql.Connection;
import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;

public class ConnectionTest {

    
    @Test
    public void test1() throws SQLException {

        //提供mysql中Driver接口的实现类
        Driver driver = new com.mysql.jdbc.Driver();

        //注册驱动
        DriverManager.registerDriver(driver);

        String url = "jdbc:mysql://localhost:3306/wanzi";  //wanzi:表示具体的数据库名
        String user = "root";
        String password = "666666";

        //获取连接
        Connection connection = DriverManager.getConnection(url, user, password);
        System.out.println(connection);

    }

    
    @Test
    public void test2() throws SQLException, ClassNotFoundException, IllegalAccessException, InstantiationException {

        //提供mysql中Driver接口的实现类的对象
        String className = "com.mysql.jdbc.Driver";
        Class clazz = Class.forName(className);
        Driver driver = (Driver) clazz.newInstance();

        //注册驱动
        DriverManager.registerDriver(driver);

        String url = "jdbc:mysql://localhost:3306/wanzi";  //wanzi:表示具体的数据库名
        String user = "root";
        String password = "666666";

        //获取连接
        Connection connection = DriverManager.getConnection(url, user, password);
        System.out.println(connection);

    }

    
    @Test
    public void test3() throws SQLException, ClassNotFoundException, IllegalAccessException, InstantiationException {

        //1. 获取连接的4个基本信息
        String className = "com.mysql.jdbc.Driver";
        String url = "jdbc:mysql://localhost:3306/wanzi";  //wanzi:表示具体的数据库名
        String user = "root";
        String password = "abc123";

        //2. 加载驱动
        Class.forName(className);

        //注册驱动
//        DriverManager.registerDriver(driver);
        

        //3. 获取连接
        Connection connection = DriverManager.getConnection(url, user, password);
        System.out.println(connection);

    }

    
    @Test
    public void test4() throws Exception {

        //读取配置文件中的4个基本信息
        Properties pros = new Properties();

        //加载资源的路径  默认为：src下
        InputStream is = ClassLoader.getSystemClassLoader().getResourceAsStream("jdbc.properties");
        pros.load(is);

        String className = pros.getProperty("className");
        String url = pros.getProperty("url");
        String user = pros.getProperty("user");
        String password = pros.getProperty("password");

        //2. 加载驱动
        Class.forName(className);

        //3. 获取连接
        Connection connection = DriverManager.getConnection(url, user, password);
        System.out.println(connection);
    }
}