Java：连接mysql数据库的五种方式 【代码】Java：连接mysql数据库的五种方式。

方式1

public void connect01() throws SQLException {
 Driver driver = new Driver();
 String url = "jdbc:mysql://localhost:3306/db02";
 Properties properties = new Properties();
 properties.setProperty("user", "root");
 properties.setProperty("password", "1234");
 Connection connect = driver.connect(url, properties);
 System.out.println(connect);
 }

方式2

public void connect02() throws ClassNotFoundException, InstantiationException, IllegalAccessException, SQLException {
 Class aClass = Class.forName("com.mysql.jdbc.Driver");
 Driver driver = (Driver) aClass.newInstance();
 String url = "jdbc:mysql://localhost:3306/db02";
 Properties properties = new Properties();
 properties.setProperty("user", "root");
 properties.setProperty("password", "1234");
 Connection connect = driver.connect(url, properties);
 System.out.println(connect);
 }

方式3

//方式3 使用DriverManager 替代 Diver 进行统一管理 扩展性更好一点
 public void connect03() throws ClassNotFoundException, InstantiationException, IllegalAccessException, SQLException {
 //
 Class aClass = Class.forName("com.mysql.jdbc.Driver");
 Driver driver = (Driver) aClass.newInstance();
 String url = "jdbc:mysql://localhost:3306/db02";
 String user = "root";
 String password = "1234";
 DriverManager.registerDriver(driver);//注册Driver驱动
 Connection connection = DriverManager.getConnection(url, user, password);
 System.out.println(connection);
 }

方式4

//方式4 使用Class.forName 自动完成注册驱动 简化代码
 //这种方式获取连接是使用最多的，推荐使用
 public void connect04() throws ClassNotFoundException, SQLException {
 //使用反射加载 Driver类
 //在加载 Driver类时 完成注册
 /*
 * 源码 1. 静态代码块 在类加载的时候 会执行一次
 * 2.DriverManager.registerDriver(new Driver());
 * 3.因此注册Driver的工作已经完成
 * static{
 * try{
 * DriverManager.registerDriver(new Driver());
 * }catch(SQLException var1){
 * throw new RuntimeException("Can't register driver!");
 * }
 * }
 * }
 * */
 Class.forName("com.mysql.jdbc.Driver");
 //1.mysql驱动5.1.6可以无需Class.forName("com.mysql.jdbc.Driver")
 //2.从jdk1.5以后使用了jdbc4 不再需要显示调用class.forName()注册驱动而是自动调用驱动
 // jar包下META-INF/services/java.sql.Driver文本中的类名称去注册
 //3.建议还是写上Class.forName("com.mysql.jdbc.Driver")，更加明确
 //创建url 和 user 和 password
 String url = "jdbc:mysql://localhost:3306/db02";
 String user = "root";
 String password = "1234";
 Connection connection = DriverManager.getConnection(url, user, password);
 System.out.println(connection);
 }

方式5

//方式5 在方式4的基础上改进 增加配置文件 让连接mysql更加灵活
 public void connect05() throws IOException, ClassNotFoundException, SQLException {
 //通过Properties对象获取配置文件的信息
 Properties properties = new Properties();
 properties.load(new FileInputStream("src/mysql.properties"));
 //获取相关的值
 String user = properties.getProperty("user");
 String password = properties.getProperty("password");
 String driver = properties.getProperty("driver");
 String url = properties.getProperty("url");
 Class.forName(driver);
 Connection connection = DriverManager.getConnection(url, user, password);
 System.out.println(connection);
 }