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package com.jchanghong.cache.impl;
import java.io.Serializable;
import java.util.Iterator;
import java.util.NoSuchElementException;
/**
* {@link AbstractCache} 的CacheObj迭代器.
*
* @author looly
*
* @param 键类型
* @param 值类型
* @since 4.0.10
*/
public class CacheObjIterator implements Iterator>, Serializable {
private static final long serialVersionUID = 1L;
private final Iterator> iterator;
private CacheObj nextValue;
/**
* 构造
*
* @param iterator 原{@link Iterator}
*/
CacheObjIterator(Iterator> iterator) {
this.iterator = iterator;
nextValue();
}
/**
* @return 是否有下一个值
*/
@Override
public boolean hasNext() {
return nextValue != null;
}
/**
* @return 下一个值
*/
@Override
public CacheObj next() {
if (false == hasNext()) {
throw new NoSuchElementException();
}
final CacheObj cachedObject = nextValue;
nextValue();
return cachedObject;
}
/**
* 从缓存中移除没有过期的当前值，此方法不支持
*/
@Override
public void remove() {
throw new UnsupportedOperationException("Cache values Iterator is not support to modify.");
}
/**
* 下一个值，当不存在则下一个值为null
*/
private void nextValue() {
while (iterator.hasNext()) {
nextValue = iterator.next();
if (nextValue.isExpired() == false) {
return;
}
}
nextValue = null;
}
}