二十、curator recipes之NodeCache

简介 

Curator的NodeCache允许你监听一个节点，当节点数据更改或者节点被删除的时候将会触发监听。

官方文档：http://curator.apache.org/curator-recipes/node-cache.html

javaDoc：http://curator.apache.org/apidocs/org/apache/curator/framework/recipes/cache/NodeCache.html

代码示例

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.recipes.cache.NodeCache;
import org.apache.curator.retry.ExponentialBackoffRetry;

public class NodeCacheDemo {
    private static CuratorFramework client = CuratorFrameworkFactory.newClient("localhost:2181", new ExponentialBackoffRetry(3000, 1));
    private static String path = "/nodeCache/test/0001";
    static {
        client.start();
    }

    public static void main(String[] args) throws Exception {
        if (client.checkExists().forPath(path) == null) {
            System.out.println("not exist");
            client.create().creatingParentsIfNeeded().forPath(path);
        }
        System.out.println("created");
        NodeCache nodeCache = new NodeCache(client, path, false);
        nodeCache.getListenable().addListener(() -> System.out.println("nodeChanged"));
        System.out.println("add listener");
        nodeCache.start(true);
        System.out.println("cache started");
        client.setData().forPath(path, "lay".getBytes());
        System.out.println("set data");
        client.delete().forPath(path);
        System.out.println("deleted");
        Thread.sleep(3000);
        nodeCache.close();
        System.out.println("listener closed");
        Thread.sleep(50000);
        client.close();
    }
}