JDBC 获取数据库连接

如下

package com.jdbc.connection;

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 {
    //方式一
    @Test
    public void testConnection1() throws SQLException {
        Driver driver = new com.mysql.jdbc.Driver();//获取Driver的实现类对象
        String url = "jdbc:mysql://localhost:3306/bookdb";
        Properties info = new Properties();
        info.setProperty("user","root");
        info.setProperty("password","");

        Connection conn = driver.connect(url, info);
        System.out.println(conn);
    }
    //方式二：对方式一迭代
    @Test
    public void testConnection2() throws Exception {
        //获取Driver的实现类对象（使用反射）
        Class clazz = Class.forName("com.mysql.jdbc.Driver()");
        Driver driver = (Driver) clazz.newInstance();

        //要链接的数据库
        String url = "jdbc:mysql://localhost:3306/bookdb";

        //获取需要的用户名和密码
        Properties info = new Properties();
        info.setProperty("user","root");
        info.setProperty("password","");

        //获取连接
        Connection conn = driver.connect(url, info);
        System.out.println(conn);
    }
    //方式三：使用DriverManager替代Driver
    @Test
    public void testConnection3() throws Exception {
        //获取Driver的实现类对象（使用反射）
        Class clazz = Class.forName("com.mysql.jdbc.Driver()");
        Driver driver = (Driver) clazz.newInstance();

        //提供连接的基本信息
        String url = "jdbc:mysql://localhost:3306/bookdb";
        String user = "root";
        String password = "";

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

        //获取连接
        Connection conn = DriverManager.getConnection(url, user, password);
        System.out.println(conn);
    }
    @Test
    public void testConnection4() throws Exception {
        //提供连接的基本信息
        String url = "jdbc:mysql://localhost:3306/bookdb";
        String user = "root";
        String password = "";

        //加载Driver
        Class.forName("com.mysql.jdbc.Driver()");

        //获取连接
        Connection conn = DriverManager.getConnection(url, user, password);
        System.out.println(conn);
        System.out.println(conn);
    }
    //方式五：将数据库连接需要的4个基本信息声明在配置文件中
    @Test
    public void testConnection5() throws Exception {
        //1.获取配置文件中4个基本信息
        InputStream is = ConnectionTest.class.getClassLoader().getResourceAsStream("jdbc.properties");

        Properties pros = new Properties();
        pros.load(is);

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

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

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


}