java database connection

依靠底层驱动 实现统一规范

  1.  加载数据库驱动

  DriverManager.registerDriver(new com.mysql.jdbc.Driver());

  2.  建立连接

  String username = "root";

  String password = "password" ;

  String url = "jdbc:mysql://localhost:3306/test"; 

  Connection conn = DriverManager.getConnection(url,username,password);

  3.  创建语句对象 并 发送语句 

  Statement st = conn.createStatement();

  ResultSet rs = st.executeQuery(sql);

  4.  从ResultSet中取数据 

  while(rs.next()) { //ResultSet默认指针是指到0

String userID = rs.getInt(1);

String userName = rs.getString(2); 

String password = rs.getString(3);

System.out.println(userID+" "+userName+" "+password) ;

  }

  5.  断开数据库连接

  rs.close();

  st.close();

  conn.close();