Posted on 2011-04-22 15:59
asdtiang 阅读(7921)
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boolean isKeyInCache(java.lang.Object key)
- An inexpensive check to see if the key exists in the cache.
-
-
- Parameters:
key - the key to check for
- Returns:
- true if an Element matching the key is found in the cache. No assertions are made about the state of the Element.
这个方法是Ehcache的方法，它只判断key是否存在，并不判断这个缓存元素过期没有，所以当元素加入缓存时key就一直存在，所以就算元素过期，只要key被缓存过一次，这个方法就返回true,
即缓存元素被移除的话，key还存在。
程序就不能用这个方法来判断缓存中是否存在这个某个缓存元素。
得用如下方法：
getQuiet
Element getQuiet(java.lang.Object key)
throws java.lang.IllegalStateException,
CacheException
- Gets an element from the cache, without updating Element statistics. Cache statistics are also not updated.
-
-
- Parameters:
key - a serializable value
- Returns:
- the element, or null, if it does not exist.
- Throws:
java.lang.IllegalStateException - if the cache is not Status.STATUS_ALIVE
CacheException
- Since:
- 1.2
- See Also:
isExpired(net.sf.ehcache.Element)
isExpired
boolean isExpired(Element element)
throws java.lang.IllegalStateException,
java.lang.NullPointerException
- Checks whether this cache element has expired.
The element is expired if:
- the idle time is non-zero and has elapsed, unless the cache is eternal; or
- the time to live is non-zero and has elapsed, unless the cache is eternal; or
- the value of the element is null.
-
-
- Parameters:
element - the element to check
- Returns:
- true if it has expired
- Throws:
java.lang.IllegalStateException - if the cache is not Status.STATUS_ALIVE
java.lang.NullPointerException - if the element is null
示例代码：
Element element=cache.getQuiet(key);
log.info("element:"+element);
if(element!=null)
{
log.info("cache.isExpired(element):"+cache.isExpired(element));
log.info("cacheName:" + cacheName + " key:" + key + " isExist:true");
return true;
}
else{
log.info("cacheName:" + cacheName + " key:" + key + " isExist:false");
return false;
}天苍苍，野茫茫，风吹草底见牛羊