Mock Objects：缺点和用例

public final class IgnoreExceptionsCacheManagerDecorator implements CacheManager {
 
  private static final Object NULL = new Object();
  private static Logger logger = Logger.getAnonymousLogger(); 
 
  private final CacheManager decorated;
  
  public IgnoreExceptionsCacheManagerDecorator(CacheManager decorated) {
    this.decorated = decorated;
  }
  
  public Object getFromCache(String key) {
    try {
      return decorated.getFromCache(key);
    } catch (Exception e) {
      logger.log(SEVERE, "Unable to retrieve an object using key \"" + key + "\"", e);            
    }
    return NULL;
  }
 
  public void putInCache(String key, Object o) {
    try {
      decorated.putInCache(key, o);
    } catch (Exception e) {
      logger.log(SEVERE, "Unable to store the object " + o + " using key \"" + key + "\"", e);            
    }
  }
}
　　为了避免缓存系统中的任何错误导致产品中某些应用程序停止运行，我们仅需要使用IgnoreExceptionsCacheManagerDecorator ：

X)V$uM8o:H9|　　CacheManager cacheManager = new IgnoreExceptionsCacheManagerDecorator(new DistributedCacheManager());