Class.forName("com.mysql.jdbc.Driver"); this.conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/daodb","root","password");
输出conn 为啥是NULL
Class.forName("com.mysql.jdbc.Driver"); this.conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/daodb","root","password");
输出conn 为啥是NULL