memcached的使用（二）hibernate cache provider
实现hibernate的cache provider，让hibernate使用memcached缓存。
这里比较简单，由于memcached的SockIOPool已经在（一）中spring中初始化了，这里就不考虑pool的初始化，直接获得MemCachedClient使用即可。
然后配置给hibernate<prop key="hibernate.cache.provider_class">×××</prop>
附代码：
/** * @author Marc * */public class MemcachedProvider implements CacheProvider {public Cache buildCache(String name, Properties properties) throws CacheException {return new MemCache(name);}public boolean isMinimalPutsEnabledByDefault() {return false;}public long nextTimestamp() {return Timestamper.next();}public void start(Properties properties) throws CacheException {}public void stop() {}}/** * @author Marc * */public class MemCache implements Cache {private static final Log log = LogFactory.getLog(MemCache.class);private static final int SIXTY_THOUSAND_MS = 60000;MemCachedClient mc;String regionName;/** * Creates a new Hibernate pluggable cache based on a cache name. <p/> * * @param cache * The underlying EhCache instance to use. */public MemCache(String regionName) {mc = new MemCachedClient();mc.setCompressEnable(false);this.regionName = regionName;}/** * Gets a value of an element which matches the given key. * * @param key * the key of the element to return. * @return The value placed into the cache with an earlier put, or null if * not found or expired * @throws CacheException */public Object get(Object key) throws CacheException {if (log.isDebugEnabled()) {log.debug("key: " + key);}if (key == null) {return null;} else {Object rt = mc.get(key.toString());if (rt == null) {if (log.isDebugEnabled()) {log.debug("Element for " + key + " is null");}return null;} else {return rt;}}}public Object read(Object key) throws CacheException {return get(key);}/** * Puts an object into the cache. * * @param key * a key * @param value * a value * @throws CacheException * if the {@link CacheManager} is shutdown or another * {@link Exception} occurs. */public void update(Object key, Object value) throws CacheException {put(key, value);}/** * Puts an object into the cache. * * @param key * a key * @param value * a value * @throws CacheException * if the {@link CacheManager} is shutdown or another * {@link Exception} occurs. */public void put(Object key, Object value) throws CacheException {mc.set(key.toString(), value);}/** * Removes the element which matches the key. <p/> If no element matches, * nothing is removed and no Exception is thrown. * * @param key * the key of the element to remove * @throws CacheException */public void remove(Object key) throws CacheException {mc.delete(key.toString());}/** * Remove all elements in the cache, but leave the cache in a useable state. * * @throws CacheException */public void clear() throws CacheException {log.warn("cann't clear all items in memcached!");throw new CacheException("cann't clear all items in memcached!");}/** * Remove the cache and make it unuseable. * * @throws CacheException */public void destroy() throws CacheException {}/** * Calls to this method should perform there own synchronization. It is * provided for distributed caches. Because EHCache is not distributed this * method does nothing. */public void lock(Object key) throws CacheException {}/** * Calls to this method should perform there own synchronization. It is * provided for distributed caches. Because EHCache is not distributed this * method does nothing. */public void unlock(Object key) throws CacheException {}/** * Gets the next timestamp; */public long nextTimestamp() {return Timestamper.next();}/** * Returns the lock timeout for this cache. */public int getTimeout() {// 60 second lock timeoutreturn Timestamper.ONE_MS * SIXTY_THOUSAND_MS;}public String getRegionName() {return this.regionName;}/** * Warning: This method can be very expensive to run. Allow approximately 1 * second per 1MB of entries. Running this method could create liveness * problems because the object lock is held for a long period <p/> * * @return the approximate size of memory ehcache is using for the * MemoryStore for this cache */public long getSizeInMemory() {log.warn("cann't getSizeInMemory in memcached!");throw new CacheException("cann't getSizeInMemory in memcached!");}public long getElementCountInMemory() {log.warn("cann't getElementCountInMemory in memcached!");throw new CacheException("cann't getElementCountInMemory in memcached!");}public long getElementCountOnDisk() {log.warn("cann't getElementCountOnDisk in memcached!");throw new CacheException("cann't getElementCountOnDisk in memcached!");}public Map toMap() {log.warn("cann't toMap in memcached!");throw new CacheException("cann't toMap in memcached!");}public String toString() {return "MemCached(" + getRegionName() + ')';}} /** * 取key的hashCode做为memcached的key，避免key中的一些特殊符号导致memcached工作异常 * @param key * @return hashCode后的key */ private String encodeKey(Object key) { int hashCode = new HashCodeBuilder(-167198555, -754611037).append(String.valueOf(key)).append(getRegionName()).toHashCode(); return String.valueOf(hashCode); } 4 楼 lanhuai 2007-01-19 把这个encodeKey返回的结果传给MemCachedClient 的方法，就可以了 5 楼 lanhuai 2007-01-19 请高手来鉴定一下我的方法是否有问题？？ 6 楼 hqman 2007-07-31 求助高手！！！！！！！！！！1