Ehcache - hello world

Key Classes

CacheManager

The CacheManager class is used to manage caches. Creation of, access to, and removal of caches is controlled by a named CacheManager.

Cache

A Cache is a thread-safe logical representation of a set of data elements, analogous to a cache region in many caching systems. Once a reference to a cache is obtained (through a CacheManager), logical actions can be performed. The physical implementation of these actions is relegated to the stores.

Element

An element is an atomic entry in a cache. It has a key, a value, and a record of accesses. Elements are put into and removed from caches. They can also expire and be removed by the cache, depending on the cache settings.

 

Creating a CacheManager

Create a new CacheManager or return the existing one named in the configuration.
　　CacheManager.newInstance(Configuration configuration)

Create a new singleton CacheManager with default configuration, or return the existing singleton.
　　CacheManager.create()
　　CacheManager.getInstance()

Create a singleton CacheManager with the passed-in configuration, or return the existing singleton.
　　CacheManager.create(Configuration configuration)

Create a new CacheManager, or throw an exception if the CacheManager named in the configuration already exists or if the parameter (configuration) is null.
　　new CacheManager(Configuration configuration)

Create a singleton CacheManager with the passed-in configuration, or return the existing singleton.
　　CacheManager.create(Configuration configuration)

 

Loading a Configuration

The following creates a CacheManager based on the configuration defined in the ehcache.xml file in the classpath.

CacheManager manager = CacheManager.newInstance();

The following creates a CacheManager based on a specified configuration file.

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

The following creates a CacheManager from a configuration resource in the classpath.

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

The following creates a CacheManager from a configuration in an InputStream.

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

 

Performing Basic Cache Operations

Obtaining a reference to a Cache

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

Putting an Element in Cache

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

Updating and Element in Cache

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

Getting an Element from Cache - The following gets a Serializable value from an element with a key of key1 .

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

Getting an Element from Cache - The following gets a NonSerializable value from an element with a key of key1 .

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

Removing an Element from Cache

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

Obtaining Cache Sizes - The following gets the number of elements currently in the cache.

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

Obtaining Cache Sizes - The following gets the number of elements currently in the MemoryStore.

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

Obtaining Cache Sizes - The following gets the number of elements currently in the DiskStore.

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

 

Shutdown the CacheManager

The following shuts down the singleton CacheManager:

CacheManager.getInstance().shutdown();

The following shuts down a CacheManager instance, assuming you have a reference to the CacheManager called cacheManager :

cacheManager.shutdown();