ehcache如何判断缓存数据是否存在--isKeyInCache

 

Posted on 2011-04-22 15:59 asdtiang 阅读(5552) 评论(0)  编辑  收藏 ehcache如何判断缓存数据是否存在--isKeyInCache
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:

  1. the idle time is non-zero and has elapsed, unless the cache is eternal; or
  2. the time to live is non-zero and has elapsed, unless the cache is eternal; or
  3. 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:
ehcache如何判断缓存数据是否存在--isKeyInCacheElement element=cache.getQuiet(key);
ehcache如何判断缓存数据是否存在--isKeyInCache        log.info("element:"+element);
ehcache如何判断缓存数据是否存在--isKeyInCache        if(element!=null){
ehcache如何判断缓存数据是否存在--isKeyInCache            log.info("cache.isExpired(element):"+cache.isExpired(element));
ehcache如何判断缓存数据是否存在--isKeyInCache            log.info("cacheName:" + cacheName + " key:" + key + " isExist:true");
ehcache如何判断缓存数据是否存在--isKeyInCache            return true;
ehcache如何判断缓存数据是否存在--isKeyInCache        }
ehcache如何判断缓存数据是否存在--isKeyInCache        else{
ehcache如何判断缓存数据是否存在--isKeyInCache            log.info("cacheName:" + cacheName + " key:" + key + " isExist:false");
ehcache如何判断缓存数据是否存在--isKeyInCache            return false;
ehcache如何判断缓存数据是否存在--isKeyInCache        }


ehcache如何判断缓存数据是否存在--isKeyInCache

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