JDBC的各种连接方式

JDBC的各种连接方式

终极版

// 最终版
// 将配置写在配置文件中，用流读取
@Test
public void finalTestConnection() throws Exception {
    // 读取配置文件
    Properties properties = new Properties();
    // 拿到配置文件的流
    FileInputStream is = new FileInputStream("src/jdbc.properties");
    properties.load(is);

    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(connection);
}

配置文件

driver=com.mysql.jdbc.Driver
user=root
password=coderDreams
url=jdbc:mysql://localhost:3306/demo1?serverTimezone=UTC&characterEncoding=utf8&useUnicode=true&useSSL=false

原始方式1

// 调用接口的方法
@Test
public void testConnection01() throws SQLException {
    // 拿到Driver接口对象
    Driver driver = new com.mysql.jdbc.Driver();
    // 调用方法拿到Connection

    String url = "jdbc:mysql://localhost:3306/demo1?serverTimezone=UTC&characterEncoding=utf8&useUnicode=true&useSSL=false";
    Properties info = new Properties();
    info.setProperty("user","root");
    info.setProperty("password","coderDreams");
    Connection connect = driver.connect(url, info);
    System.out.println(connect);
}

方式2

// 改变拿到接口对象的方法，提高可扩展性
@Test
public void testConnection02() throws Exception {
    // 拿到Driver接口对象
    Driver driver = (Driver) Class.forName("com.mysql.jdbc.Driver").newInstance();
    // 调用方法拿到Connection

    String url = "jdbc:mysql://localhost:3306/demo1?serverTimezone=UTC&characterEncoding=utf8&useUnicode=true&useSSL=false";
    Properties info = new Properties();
    info.setProperty("user","root");
    info.setProperty("password","coderDreams");
    Connection connect = driver.connect(url, info);
    System.out.println(connect);
}

方式3

// 使用DriverManager替换Driver
@Test
public void testConnection03() throws Exception {
    // 拿到Driver接口对象
    Driver driver = (Driver) Class.forName("com.mysql.jdbc.Driver").newInstance();
    // 注册驱动
    DriverManager.registerDriver(driver);

    String url = "jdbc:mysql://localhost:3306/demo1?serverTimezone=UTC&characterEncoding=utf8&useUnicode=true&useSSL=false";
    Properties info = new Properties();
    info.setProperty("user","root");
    info.setProperty("password","coderDreams");
    Connection connection = DriverManager.getConnection(url, info);
    System.out.println(connection);
}

方式4(常用)

// 发现类加载时会自动注册
@Test
public void testConnection04() throws Exception {
    // 拿到Driver接口对象
    Class.forName("com.mysql.jdbc.Driver");

    String url = "jdbc:mysql://localhost:3306/demo1?serverTimezone=UTC&characterEncoding=utf8&useUnicode=true&useSSL=false";
    Properties info = new Properties();
    info.setProperty("user","root");
    info.setProperty("password","coderDreams");
    Connection connection = DriverManager.getConnection(url, info);
    System.out.println(connection);
}

方式5(了解)

// 发现驱动加载时会自动注册
@Test
public void testConnection05() throws Exception {
    // 省略了类加载
    // 但是不推荐，降低了扩展性
    String url = "jdbc:mysql://localhost:3306/demo1?serverTimezone=UTC&characterEncoding=utf8&useUnicode=true&useSSL=false";
    Properties info = new Properties();
    info.setProperty("user","root");
    info.setProperty("password","coderDreams");
    Connection connection = DriverManager.getConnection(url, info);
    System.out.println(connection);
}