public ResultSet queryResult(String sql, String[] params) {
		try {
			Class.forName(driver);
			System.out.println("ɹ");
			connection = DriverManager.getConnection(url,username,password);	 //ݿ
			System.out.println("ݿɹ!");
			ps = connection.prepareStatement(sql);			//ȡPreparedStatement
			
			//ѭϣSQLе"?"
			for (int i = 0; i < params.length; i++) {
				ps.setString(i+1, params[i]);
			}
			//ѯݿȡResultSet
			rs = ps.executeQuery();			
		} catch (SQLException e) {
			// TODO: handle exception
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			// TODO: handle exception
			e.printStackTrace();
		} finally {
		}
		return rs;		//ResultSet
	}