数据库连接的5种方式

package connection;

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

public class ConnectionTest {
    public static void main(String[] args) throws Exception {
        testConnection5();
    }

//    方式一
    public static void testConnection1() throws SQLException {
//        获取driver的实现类
        Driver driver = new com.mysql.jdbc.Driver();
//        jdbc:mysql:协议；localhost:类似于ip地址；3306：端口号；test:数据库；问号：切换一下编码格式
        String url = "jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf8";
//        将用户名和密码封装在Properties里面
        Properties info = new Properties();
        info.setProperty("user", "victor");
        info.setProperty("password", "136019");
        Connection conn = driver.connect(url, info);
        System.out.println(conn);
    }

//    方式二，使用反射获取driver的实现类对象
    public static void testConnection2() throws Exception {
//        使用反射获取driver的实现类对象
        Class clazz = Class.forName("com.mysql.jdbc.Driver");
        Driver driver = (Driver) clazz.newInstance();
//        jdbc:mysql:协议；localhost:类似于ip地址；3306：端口号；test:数据库；问号：切换一下编码格式
        String url = "jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf8";
//        将用户名和密码封装在Properties里面
        Properties info = new Properties();
        info.setProperty("user", "victor");
        info.setProperty("password", "136019");
        Connection conn = driver.connect(url, info);
        System.out.println(conn);
    }

//    方式三
    public static void testConnection3() throws Exception {
//        1.提供三个基本信息
        Class clazz = Class.forName("com.mysql.jdbc.Driver");
        Driver driver = (Driver) clazz.newInstance();
        // 注册驱动
        DriverManager.registerDriver(driver);
//        获取连接
        String url = "jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf8";
        String user = "victor";
        String password = "136019";
        Connection connection = DriverManager.getConnection(url, user, password);
        System.out.println(connection);

    }

//    方式4 只加载驱动 不用显示的注册驱动
    public static void testConnection4() throws Exception {
//        1.提供三个基本信息
        Class clazz = Class.forName("com.mysql.jdbc.Driver");
//        Driver driver = (Driver) clazz.newInstance();
        // 注册驱动
//        DriverManager.registerDriver(driver);
//        获取连接
        String url = "jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf8";
        String user = "victor";
        String password = "136019";
        Connection connection = DriverManager.getConnection(url, user, password);
        System.out.println(connection);

    }

//    方式5 将数据库连接需要的4个基本信息声明在配置文件中，通过读取配置文件的方式，获取连接
//    好处：实现了数据与代码的分离，实现了解耦；如果需要修改配置信息，可以避免程序重新打包，直接修改配置文件即可，不需要修改代码包
    public static void testConnection5() throws Exception {
//        1.读取配置文件中的4个基本信息
        InputStream is = ConnectionTest.class.getClassLoader().getResourceAsStream("jdbc.properties");
        Properties properties = new Properties();
        properties.load(is);
        String user = properties.getProperty("user");
        String password = properties.getProperty("password");
        String url = properties.getProperty("url");
        String driverClass = properties.getProperty("driverClass");
//        2.加载驱动
        Class.forName(driverClass);
//        3.获取连接
        Connection connection = DriverManager.getConnection(url, user, password);
        System.out.println(connection);
    }

}