緩衝初解（二）

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EHCAche源碼分析：

首先看緩衝類CacheManager

public class CacheManager {　　//該類在預設情況下讀取CLASSPATH下的ehcache.xml檔案，並且是單例模式建立新的緩衝類    /**     * Keeps track of all known CacheManagers. Used to check on conflicts.     * CacheManagers should remove themselves from this list during shut down.     */    public static final List ALL_CACHE_MANAGERS = Collections.synchronizedList(new ArrayList());    private static final Log LOG = LogFactory.getLog(CacheManager.class.getName());    /**     * The Singleton Instance.     */    private static CacheManager singleton;    /**     * Caches managed by this manager.     */    protected final Map caches = new HashMap();    /**     * Default cache cache.     */    private Ehcache defaultCache;

調用該類需要CacheManager manager = new VacheManager();

建立一個就要：manager.create();

   public static CacheManager create() throws CacheException {        synchronized (CacheManager.class) {            if (singleton == null) {                if (LOG.isDebugEnabled()) {                    LOG.debug("Creating new CacheManager with default config");                }                singleton = new CacheManager();            } else {                if (LOG.isDebugEnabled()) {                    LOG.debug("Attempting to create an existing singleton. Existing singleton returned.");                }            }            return singleton;        }    }

 該方法通過預設配置，以Factory 方法建立一個單例對象緩衝管理器

也可以通過getInstance()來擷取執行個體

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

 根據緩衝名稱擷取緩衝對象

  public synchronized Cache getCache(String name) throws IllegalStateException, ClassCastException {        checkStatus();        return (Cache) caches.get(name);    }

 緩衝是以Map集合儲存資料的，也可以通過

 public synchronized Ehcache getEhcache(String name) throws IllegalStateException {        checkStatus();        return (Ehcache) caches.get(name);    }

 來擷取EHcache

那緩衝是如何儲存的呢，看以下代碼就知道了

   public synchronized void addCache(String cacheName) throws IllegalStateException,            ObjectExistsException, CacheException {        checkStatus();        //NPE guard        if (cacheName == null || cacheName.length() == 0) {            return;        }        if (caches.get(cacheName) != null) {            throw new ObjectExistsException("Cache " + cacheName + " already exists");        }        Ehcache cache = null;        try {            cache = (Ehcache) defaultCache.clone();        } catch (CloneNotSupportedException e) {            LOG.error("Failure adding cache. Initial cause was " + e.getMessage(), e);        }        if (cache != null) {            cache.setName(cacheName);        }        addCache(cache);    }

 通過addCache()方法，判斷cacheName是否已經存在，如果不存在，那就在預設緩衝中複製clone()到cache裡面，也就是map裡面。如果存在就不做處理

以上是我對EHCache的一點理解，以後還會繼續補充

緩衝初解（二）