spring緩衝整合memcache

spring3.1.0開始支援註解方式的緩衝實現，非常方便，不過它目前只支援java內建的ConcurrentMap和ehcache這兩種緩衝方式，因為項目用到memcache，就想把memcache整合到spring內建的緩衝中，使memcache也能用註解方式來調用。於是參考ehcache的整合方式，把memcache整合到項目中。spring把所有緩衝都抽象為一個cache，相當於一個緩衝集合，即spring緩衝註解@Cacheable(value="xxx")中xxx對應的結果集合。首先我們要實現Cache這個介面，memcache的java用戶端我們用的是com.danga.MemCached.MemCachedClient這個，代碼如下：

public class MemcacheCache implements Cache {    private MemCachedClient client;  private String name;    public MemcacheCache(){      }    public MemcacheCache(String name,MemCachedClient client) {    Assert.notNull(client, "Memcache client must not be null");    // TODO validate memcache "alive"    this.client = client;    this.name = name;  }    @Override  @Cacheable(value="xxxx")  public String getName() {    return this.name;  }    @Override  public Object getNativeCache() {    return this.client;  }    @Override  public ValueWrapper get(Object key) {    Object value = this.client.get(objectToString(key));    return (value != null ? new SimpleValueWrapper(value) : null);  }    @Override  public void put(Object key, Object value) {    this.client.set(objectToString(key), value);      }    @Override  public void evict(Object key) {    this.client.delete(objectToString(key));      }    @Override  public void clear() {    // TODO delete all data     }    private static String objectToString(Object object) {    if (object == null) {      return null;    } else if (object instanceof String) {      return (String) object;    } else {      return object.toString();    }  }    public void setClient(MemCachedClient client){    this.client = client;  }  public MemCachedClient getClient() {    return client;  }  public void setName(String name) {    this.name = name;  }    }

然後是要擴充AbstractCacheManager這個緩衝管理抽象類別，它主要負責產生和讀取Cache，代碼如下：

public class MemcacheCacheManager extends AbstractCacheManager {    private Collection<Cache> caches;  private MemCachedClient client = null;    public MemcacheCacheManager() {  }    public MemcacheCacheManager(MemCachedClient client){    setClient(client);  }    @Override  protected Collection<? extends Cache> loadCaches() {        return this.caches;  }    public void setCaches(Collection<Cache> caches) {    this.caches = caches;  }    public void setClient(MemCachedClient client) {    this.client = client;    updateCaches();  }    public Cache getCache(String name){    checkState();        Cache cache = super.getCache(name);    if(cache == null){      cache = new MemcacheCache(name, client);      addCache(cache);    }    return cache;  }    private void checkState() {    if(client == null){      throw new IllegalStateException("MemcacheClient must not be null.");    }    //TODO check memcache state      }  private void updateCaches() {    if(caches != null){      for(Cache cache : caches){        if(cache instanceof MemcacheCache){          MemcacheCache memcacheCache = (MemcacheCache)cache;          memcacheCache.setClient(client);        }      }    }      }   }

配置bean：

<bean id="cacheManager" class="com.youboy.cshop.utils.memcache.MemcacheCacheManager"><property name="client" value="memcachedClient"/><property name="caches"><set><bean class="com.youboy.cshop.utils.memcache.MemcacheCache"><property name="name" value="testCache"/><property name="client" ref="memcachedClient"/></bean></set></property></bean>

其中memcachedClient為你memcache的用戶端，你可以配置多個MemcacheCache，配置完這裡你就你就可以把@Cacheable(value="testCache")添加到方法那來緩衝執行結果，這裡value="testCache"的值必須和上面bean檔案配置的一致，否則無法緩衝。這隻是做了個簡單的整合，還有很多要完善的，比如串連時檢查memcache狀態。