/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package com.aliyun.odps;
/**
* LazyLoad表示此类型的属性值可能是延迟加载的
*
* <p>
* 延迟加载的含义是, 对象的属性值可能不存在，在调用gets等方法时视需要通过RESTful API从服务器断获取
* </p>
*
* @author shenggong.wang@alibaba-inc.com
*/
public abstract class LazyLoad {
private boolean loaded;
/**
* 判断属性是否已经加载
*
* @return 如果对象已经被标记为已加载返回true, 否则返回false
*/
boolean isLoaded() {
return loaded;
}
/**
* 标记属性已经加载
*
* @param loaded
*/
protected void setLoaded(boolean loaded) {
this.loaded = loaded;
}
/**
* 加载属性
*
* <p>
* 如果状态为已加载则忽略
* </p>
*/
protected void lazyLoad() {
if (!loaded) {
try {
reload();
} catch (OdpsException e) {
throw new ReloadException(e.getMessage(), e);
}
}
}
/**
* 重新加载属性值
*
* @throws OdpsException
*/
public abstract void reload() throws OdpsException;
}