JDBC连接MySQL数据库

方式一：
Driver driver = new com.mysql.cj.jdbc.Driver();
String url = "jdbc:mysql://localhost:3306/test?useSSL=false&serverTimezone=UTC";
Properties into = new Properties();
into.setProperty("user","root");
into.setProperty("password","123456");
Connection conn = driver.connect(url,into);
System.out.println(conn);

方式二：
Class cls = Class.forName("com.mysql.cj.jdbc.Driver");
Driver driver = (Driver) cls.newInstance();
DriverManager.registerDriver(driver);
String url = "jdbc:mysql://localhost:3306/test?useSSL=false&serverTimezone=UTC";
String user = "root";
String password = "123456";
Connection conn = DriverManager.getConnection(url,user,password);
System.out.println(conn);

方式三：
Class cls = Class.forName("com.mysql.cj.jdbc.Driver");
String url = "jdbc:mysql://localhost:3306/test?useSSL=false&serverTimezone=UTC";
String user = "root";
String password = "123456";
Connection conn = DriverManager.getConnection(url,user,password);
System.out.println(conn);

方式四：
InputStream is = JunitTest.class.getClassLoader().getResourceAsStream("jdbc_mysql.properties");
Properties pros = new Properties();
pros.load(is);
String user = pros.getProperty("user");
String password = pros.getProperty("password");
String url = pros.getProperty("url");
String driver = pros.getProperty("driver");
Class.forName(driver);
Connection conn = DriverManager.getConnection(url,user,password);
System.out.println(conn);

//jdbc_mysql.properties文件
user=root
password=123456
url=jdbc:mysql://localhost:3306/test?useSSL=false&serverTimezone=UTC
driver=com.mysql.cj.jdbc.Driver

方式五：使用注解
//1、获取该类的字节码文件对象
Class<Test> testClass = Test.class;
//2、获取注解对象
JDBC_Mysql annotation = testClass.getAnnotation(JDBC_Mysql.class);
//2、获取连接
Class.forName(annotation.driver());
Connection conn = DriverManager.getConnection
        (annotation.url(), annotation.user(), annotation.password());
System.out.println(conn);
        
//注解
@Target({ElementType.TYPE,ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface JDBC_Mysql {
    String user() default "root";
    String password() default "123456";
    String driver () default "com.mysql.cj.jdbc.Driver";
    String url () default "jdbc:mysql://localhost:3306/test?useSSL=false&serverTimezone=UTC";
}