mysql先连接再指定数据库

Class.forName("com.mysql.jdbc.Driver");
   Connection conn = (Connection) DriverManager.getConnection("jdbc:mysql://localhost", "root", "root");
   JdbcRowSet jrs = new JdbcRowSetImpl(conn);
   //执行选择数据库操作
   jrs.setCommand("use test");   
   jrs.execute();
   jrs.setCommand("select * from user");
   jrs.execute();
   while(jrs.next()){
    System.out.println(jrs.getString(2)+"\t"+jrs.getString(3));
   }