abstractcacheadministrator.java

来自「一个不错的cache」· Java 代码 · 共 418 行 · 第 1/2 页

     * Retrieves the value of one of the configuration properties.
     *
     * @param key The key assigned to the property
     * @return Property value, or <code>null</code> if the property could not be found.
     */
    public String getProperty(String key) {
        return config.getProperty(key);
    }

    /**
     * Indicates whether the unlimited disk cache is enabled or not.
     */
    public boolean isUnlimitedDiskCache() {
        return unlimitedDiskCache;
    }

    /**
     * Check if we use overflowPersistence
     *
     * @return Returns the overflowPersistence.
     */
    public boolean isOverflowPersistence() {
        return this.overflowPersistence;
    }

    /**
     * Sets the overflowPersistence flag
     *
     * @param overflowPersistence The overflowPersistence to set.
     */
    public void setOverflowPersistence(boolean overflowPersistence) {
        this.overflowPersistence = overflowPersistence;
    }

    /**
     * Retrieves an array containing instances all of the {@link CacheEventListener}
     * classes that are specified in the OSCache configuration file.
     */
    protected CacheEventListener[] getCacheEventListeners() {
        CacheEventListener[] listeners = null;

        List classes = StringUtil.split(config.getProperty(CACHE_ENTRY_EVENT_LISTENERS_KEY), ',');
        listeners = new CacheEventListener[classes.size()];

        for (int i = 0; i < classes.size(); i++) {
            String className = (String) classes.get(i);

            try {
                Class clazz = Class.forName(className);

                if (!CacheEventListener.class.isAssignableFrom(clazz)) {
                    log.error("Specified listener class '" + className + "' does not implement CacheEventListener. Ignoring this listener.");
                } else {
                    listeners[i] = (CacheEventListener) clazz.newInstance();
                }
            } catch (ClassNotFoundException e) {
                log.error("CacheEventListener class '" + className + "' not found. Ignoring this listener.", e);
            } catch (InstantiationException e) {
                log.error("CacheEventListener class '" + className + "' could not be instantiated because it is not a concrete class. Ignoring this listener.", e);
            } catch (IllegalAccessException e) {
                log.error("CacheEventListener class '" + className + "' could not be instantiated because it is not public. Ignoring this listener.", e);
            }
        }

        return listeners;
    }

    /**
     * If there is a <code>PersistenceListener</code> in the configuration
     * it will be instantiated and applied to the given cache object. If the
     * <code>PersistenceListener</code> cannot be found or instantiated, an
     * error will be logged but the cache will not have a persistence listener
     * applied to it and no exception will be thrown.<p>
     *
     * A cache can only have one <code>PersistenceListener</code>.
     *
     * @param cache the cache to apply the <code>PersistenceListener</code> to.
     *
     * @return the same cache object that was passed in.
     */
    protected Cache setPersistenceListener(Cache cache) {
        String persistenceClassname = config.getProperty(PERSISTENCE_CLASS_KEY);

        try {
            Class clazz = Class.forName(persistenceClassname);
            PersistenceListener persistenceListener = (PersistenceListener) clazz.newInstance();

            cache.setPersistenceListener(persistenceListener.configure(config));
        } catch (ClassNotFoundException e) {
            log.error("PersistenceListener class '" + persistenceClassname + "' not found. Check your configuration.", e);
        } catch (Exception e) {
            log.error("Error instantiating class '" + persistenceClassname + "'", e);
        }

        return cache;
    }

    /**
     * Applies all of the recognised listener classes to the supplied
     * cache object. Recognised classes are {@link CacheEntryEventListener}
     * and {@link CacheMapAccessEventListener}.<p>
     *
     * @param cache The cache to apply the configuration to.
     * @return cache The configured cache object.
     */
    protected Cache configureStandardListeners(Cache cache) {
        if (config.getProperty(PERSISTENCE_CLASS_KEY) != null) {
            cache = setPersistenceListener(cache);
        }

        if (config.getProperty(CACHE_ENTRY_EVENT_LISTENERS_KEY) != null) {
            // Grab all the specified listeners and add them to the cache's
            // listener list. Note that listeners that implement more than
            // one of the event interfaces will be added multiple times.
            CacheEventListener[] listeners = getCacheEventListeners();

            for (int i = 0; i < listeners.length; i++) {
                // Pass through the configuration to those listeners that require it
                if (listeners[i] instanceof LifecycleAware) {
                    try {
                        ((LifecycleAware) listeners[i]).initialize(cache, config);
                    } catch (InitializationException e) {
                        log.error("Could not initialize listener '" + listeners[i].getClass().getName() + "'. Listener ignored.", e);

                        continue;
                    }
                }

                if (listeners[i] instanceof CacheEntryEventListener) {
                    cache.addCacheEventListener(listeners[i], CacheEntryEventListener.class);
                }

                if (listeners[i] instanceof CacheMapAccessEventListener) {
                    cache.addCacheEventListener(listeners[i], CacheMapAccessEventListener.class);
                }
            }
        }

        return cache;
    }

    /**
     * Finalizes all the listeners that are associated with the given cache object.
     * Any <code>FinalizationException</code>s that are thrown by the listeners will
     * be caught and logged.
     */
    protected void finalizeListeners(Cache cache) {
        // It's possible for cache to be null if getCache() was never called (CACHE-63)
        if (cache == null) {
            return;
        }

        Object[] listeners = cache.listenerList.getListenerList();

        for (int i = listeners.length - 2; i >= 0; i -= 2) {
            if (listeners[i + 1] instanceof LifecycleAware) {
                try {
                    ((LifecycleAware) listeners[i + 1]).finialize();
                } catch (FinalizationException e) {
                    log.error("Listener could not be finalized", e);
                }
            }
        }
    }

    /**
     * Initialize the core cache parameters from the configuration properties.
     * The parameters that are initialized are:
     * <ul>
     * <li>the algorithm class ({@link #CACHE_ALGORITHM_KEY})</li>
     * <li>the cache size ({@link #CACHE_CAPACITY_KEY})</li>
     * <li>whether the cache is blocking or non-blocking ({@link #CACHE_BLOCKING_KEY})</li>
     * <li>whether caching to memory is enabled ({@link #CACHE_MEMORY_KEY})</li>
     * <li>whether the persistent cache is unlimited in size ({@link #CACHE_DISK_UNLIMITED_KEY})</li>
     * </ul>
     */
    private void initCacheParameters() {
        algorithmClass = getProperty(CACHE_ALGORITHM_KEY);

        blocking = "true".equalsIgnoreCase(getProperty(CACHE_BLOCKING_KEY));

        String cacheMemoryStr = getProperty(CACHE_MEMORY_KEY);

        if ((cacheMemoryStr != null) && cacheMemoryStr.equalsIgnoreCase("false")) {
            memoryCaching = false;
        }

        unlimitedDiskCache = Boolean.valueOf(config.getProperty(CACHE_DISK_UNLIMITED_KEY)).booleanValue();
        overflowPersistence = Boolean.valueOf(config.getProperty(CACHE_PERSISTENCE_OVERFLOW_KEY)).booleanValue();

        String cacheSize = getProperty(CACHE_CAPACITY_KEY);

        try {
            if ((cacheSize != null) && (cacheSize.length() > 0)) {
                cacheCapacity = Integer.parseInt(cacheSize);
            }
        } catch (NumberFormatException e) {
            log.error("The value supplied for the cache capacity, '" + cacheSize + "', is not a valid number. The cache capacity setting is being ignored.");
        }
    }

    /**
     * Load the properties file from the classpath.
     */
    private void loadProps(Properties p) {
        config = new Config(p);
    }
}