Hazelcast - 集合侦听器

当给定的集合（例如，队列、集、列表等）更新时，Hazelcast 支持侦听器。

典型的事件包括添加条目和移除条目。

通过一个示例看看如何实现集侦听器。所以，假设我们想实现一个侦听器，可以跟踪集合中的元素数。

示例

public class SetTimedProducer{
   public static void main(String... args) throws IOException,
   InterruptedException {
      //initialize hazelcast instance
      HazelcastInstance hazelcast = Hazelcast.newHazelcastInstance();
      Thread.sleep(5000);
      // create a set
      ISet<String> hzFruits = hazelcast.getSet("fruits");
      hzFruits.add("Mango");
      Thread.sleep(2000);
      hzFruits.add("Apple");
      Thread.sleep(2000);
      hzFruits.add("Banana");
      System.exit(0);
   }
}

所以，让我们首先实现生成器 −

package com.example.demo;

import java.io.IOException;
import com.hazelcast.core.ISet;
import com.hazelcast.core.ItemEvent;
import com.hazelcast.core.ItemListener;
import com.hazelcast.core.Hazelcast;
import com.hazelcast.core.HazelcastInstance;

public class SetListener{
   public static void main(String... args) throws IOException, InterruptedException {
      //initialize hazelcast instance
      HazelcastInstance hazelcast = Hazelcast.newHazelcastInstance();
      // create a set
      ISet<String> hzFruits = hazelcast.getSet("fruits");
      ItemListener<String> listener = new FruitListener<String>();
      hzFruits.addItemListener(listener, true);
      System.exit(0);
   }
   private static class FruitListener<String> implements ItemListener<String> {
      private int count = 0;
      @Override
      public void itemAdded(ItemEvent<String> item) {
         System.out.println("item added" + item);
         count ++;
         System.out.println("Total elements" + count);
      }
      @Override
      public void itemRemoved(ItemEvent<String> item) {
         count --;
      }
   }
}

现在，让我们实现侦听器 −

java -cp .\target\demo-0.0.1-SNAPSHOT.jar com.example.demo.SetTimedProducer

我们首先运行生成器 −

java -cp .\target\demo-0.0.1-SNAPSHOT.jar com.example.demo.SetListener

然后，我们运行侦听器并使其一直运行 −

输出

item added: ItemEvent{
   event=ADDED, item=Mango, member=Member [localhost]:5701-c28a60b7-3259-44bf-8793-54063d244394 this}
Total elements: 1

item added: ItemEvent{
   event=ADDED, item=Apple, member=Member [localhost]:5701-c28a60b7-3259-44bf-8793-54063d244394 this}
Total elements: 2

item added: ItemEvent{
   event=ADDED, item=Banana, member=Member [localhost]:5701-c28a60b7-3259-44bf-8793-54063d244394 this}
Total elements: 3

侦听器的输出如下 −