content: /*
   * Copyright 1999-2018 Alibaba Group Holding Ltd.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.alibaba.nacos.common.notify.listener;
  
  import com.alibaba.nacos.common.notify.Event;
  
  import java.util.List;
  
  /**
   * Subscribers to multiple events can be listened to.
   *
   * @author <a href="mailto:liaochuntao@live.com">liaochuntao</a>
   * @author zongtanghu
   */
  @SuppressWarnings("PMD.AbstractClassShouldStartWithAbstractNamingRule")
  public abstract class SmartSubscriber extends Subscriber<Event> {
      
      /**
       * Returns which event type are smart subscriber interested in.
       *
       * @return The interested event types.
       */
      public abstract List<Class<? extends Event>> subscribeTypes();
      
      @Override
      public final Class<? extends Event> subscribeType() {
          return null;
      }
      
      @Override
      public final boolean ignoreExpireEvent() {
          return false;
      }
  }
  