Ehcache Samples

一. 创建CacheManager

所有ehcache的使用, 都是从 CacheManager. 开始的，有多种方法创建CacheManager实例：

1：Create a singleton CacheManager using defaults, then list caches：

String[] cacheNames = CacheManager.create().getCacheNames();

或者

String[] cacheNames = CacheManager.getInstance().getCacheNames();

查看源代码：

    public static CacheManager getInstance() throws CacheException {
        return CacheManager.create();
    }

2：Create a CacheManager instance using defaults, then list caches.

CacheManager manager = new CacheManager();
 String[] cacheNames = manager.getCacheNames();

3：Create two CacheManagers, each with a different configuration, and list the caches in each.

CacheManager manager1 = new CacheManager("src/config/ehcache1.xml");
 CacheManager manager2 = new CacheManager("src/config/ehcache2.xml");
 String[] cacheNamesForManager1 = manager1.getCacheNames();
 String[] cacheNamesForManager2 = manager2.getCacheNames();

二：Ways of loading Cache Configuration

1：Create a CacheManager using defaults. Ehcache will look for ehcache.xml in the classpath.

CacheManager manager = new CacheManager();

2：Create a CacheManager specifying the path of a configuration file.

CacheManager manager = new CacheManager("src/config/ehcache.xml");

3：Create a CacheManager from a configuration resource in the classpath.

URL url = getClass().getResource("/anotherconfigurationname.xml");
CacheManager manager = new CacheManager(url);

4：Create a CacheManager from a configuration in an InputStream.

InputStream fis = new FileInputStream(new File("src/config/ehcache.xml").getAbsolutePath());
try {
    CacheManager manager = new CacheManager(fis);
} finally {
    fis.close();
}

三. Adding and Removing Caches Programmatically
手动创建一个cache, 而不是通过配置文件

1：Add a cache using defaults, then use it. The following example creates a cache called testCache, which will be configured using defaultCache from the configuration.

CacheManager singletonManager = CacheManager.create();
singletonManager.addCache("testCache");
Cache test = singletonManager.getCache("testCache");

2：Create a Cache and add it to the CacheManager, then use it.

CacheManager singletonManager = CacheManager.create();
Cache memoryOnlyCache = new Cache("testCache", 5000, false, false, 5, 2);
manager.addCache(memoryOnlyCache);
Cache test = singletonManager.getCache("testCache");

3：Remove cache called sampleCache1

CacheManager singletonManager = CacheManager.create();
singletonManager.removeCache("sampleCache1");

四. Shutdown the CacheManager

1：Shutdown the singleton CacheManager

CacheManager.getInstance().shutdown();

2：Shutdown a CacheManager instance, assuming you have a reference to the CacheManager called manager

manager.shutdown();

五. Using Caches

1：Obtaining a reference to a Cache
Obtain a Cache called "sampleCache1", which has been preconfigured in the configuration file

Cache cache = manager.getCache("sampleCache1");

2：Performing CRUD operations
Put an element into a cache

Cache cache = manager.getCache("sampleCache1");
Element element = new Element("key1", "value1");
cache.put(element);

3：Update an element in a cache. Even though cache.put() is used, Ehcache knows there is an existing element, and considers the put an update for the purpose of notifying cache listeners.

Cache cache = manager.getCache("sampleCache1");
cache.put(new Element("key1", "value1"));
//This updates the entry for "key1"
cache.put(new Element("key1", "value2"));

4：Get a Serializable value from an element in a cache with a key of "key1".

Cache cache = manager.getCache("sampleCache1");
Element element = cache.get("key1");
Serializable value = element.getValue();

5：Get a NonSerializable value from an element in a cache with a key of "key1".

Cache cache = manager.getCache("sampleCache1");
Element element = cache.get("key1");
Object value = element.getObjectValue();

6：Remove an element from a cache with a key of "key1".

Cache cache = manager.getCache("sampleCache1");
cache.remove("key1");

六. Disk Persistence on demand

1:sampleCache1 has a persistent diskStore. We wish to ensure that the data and index are written immediately.

Cache cache = manager.getCache("sampleCache1");
cache.flush();

七. Obtaining Cache Sizes

1：Get the number of elements currently in the Cache.

Cache cache = manager.getCache("sampleCache1");
int elementsInMemory = cache.getSize();

2：Get the number of elements currently in the MemoryStore.

Cache cache = manager.getCache("sampleCache1");
long elementsInMemory = cache.getMemoryStoreSize();

3：Get the number of elements currently in the DiskStore.

Cache cache = manager.getCache("sampleCache1");
long elementsInMemory = cache.getDiskStoreSize();

八. Obtaining Statistics of Cache Hits and Misses

1：Get the number of times requested items were found in the cache. i.e. cache hits

Cache cache = manager.getCache("sampleCache1");
int hits = cache.getHitCount();

2：Get the number of times requested items were found in the MemoryStore of the cache.

Cache cache = manager.getCache("sampleCache1");
int hits = cache.getMemoryStoreHitCount();

3：Get the number of times requested items were found in the DiskStore of the cache.

Cache cache = manager.getCache("sampleCache1");
int hits = cache.getDiskStoreCount();

4：Get the number of times requested items were not found in the cache. i.e. cache misses.

Cache cache = manager.getCache("sampleCache1");
int hits = cache.getMissCountNotFound();

5：Get the number of times requested items were not found in the cache due to expiry of the elements.

Cache cache = manager.getCache("sampleCache1");
int hits = cache.getMissCountExpired();