Posted on 2011-04-22 15:59
asdtiang 閱讀(7964)
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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.
這個方法是Ehcache的方法，它只判斷key是否存在，并不判斷這個緩存元素過期沒有，所以當元素加入緩存時key就一直存在，所以就算元素過期，只要key被緩存過一次，這個方法就返回true,
即緩存元素被移除的話，key還存在。
程序就不能用這個方法來判斷緩存中是否存在這個某個緩存元素。
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
示例代碼：
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;
}天蒼蒼，野茫茫，風吹草底見牛羊