package net.suberic.util.cache; /** * This represents a cached object. It stores the object itself, plus * the size and last accessed time. */ public class SizedCacheEntry { // the stored object itself. note that this could be a reference to // another object, or a source from which the object may be accessed. protected Object cachedValue; // the last accessed time protected long lastAccessedTime; // the size that the cachedValue occupies in the cache. protected long size = 0; /** * Creates a new, empty SizedCacheEntry. */ public SizedCacheEntry() { } /** * Creates a new SizedCacheEntry containing value which has been most * recently accessed now. */ public SizedCacheEntry(Object value) { cachedValue = value; // yeah, whatever... size = value.toString().length(); touchEntry(); } /** * This gets the cached value. Implementations may vary for this. */ public Object getCachedValue() { return cachedValue; } /** * Deletes this entry. Should be called in order to clean up entries * for which simple removal from memory is insufficient. * * The default implementation does nothing; subclasses should override * this method if cleanup is required. */ public boolean removeFromCache() { return true; } /** * Touches the SizedCacheEntry, making its last accessed time now. */ public void touchEntry() { lastAccessedTime = System.currentTimeMillis(); } /** * Gets the size of this SizedCacheEntry. */ public long getSize() { return size; } /** * Gets the last accessed time for this entry. */ public long getLastAccessedTime() { return lastAccessedTime; } /** * Compares the underlying value for equality. */ public boolean equals(Object o) { if (o != null) { Object testValue = null; if (o instanceof SizedCacheEntry) { testValue = ((SizedCacheEntry)o).getCachedValue(); } else { testValue = o; } return o.equals(cachedValue); } return (cachedValue == null); } }
