<!-- zookeeper -->
<dependency>
    <groupId>org.apache.zookeeper</groupId>
    <artifactId>zookeeper</artifactId>
    <version>3.4.14</version>
    <exclusions>
        <exclusion>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
        </exclusion>
        <exclusion>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<!-- curator-framework -->
<dependency>
    <groupId>org.apache.curator</groupId>
    <artifactId>curator-framework</artifactId>
    <version>4.2.0</version>
    <exclusions>
        <exclusion>
            <groupId>org.apache.zookeeper</groupId>
            <artifactId>zookeeper</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<!-- curator-recipes -->
<dependency>
	<groupId>org.apache.curator</groupId>
	<artifactId>curator-recipes</artifactId>
	<version>4.2.0</version>
	<exclusions>
		<exclusion>
			<groupId>org.apache.curator</groupId>
			<artifactId>curator-framework</artifactId>
		</exclusion>
	</exclusions>
</dependency>

// 多個地址逗號隔開
CuratorFramework client = CuratorFrameworkFactory.builder().connectString("localhost:2181")
        .sessionTimeoutMs(1000)    // 連接超時時間
        .connectionTimeoutMs(1000) // 會話超時時間
        // 剛開始重試間隔為1秒，之后重試間隔逐漸增加，最多重試不超過三次
        .retryPolicy(new ExponentialBackoffRetry(1000, 3))
        .build();
client.start();
//...
CloseableUtils.closeQuietly(client);//建議放在finally塊中

// 多個地址逗號隔開
CuratorFramework client = CuratorFrameworkFactory.newClient("localhost:2181",
		// 剛開始重試間隔為1秒，之后重試間隔逐漸增加，最多重試不超過三次
        new ExponentialBackoffRetry(1000, 3));
client.start();
//...
CloseableUtils.closeQuietly(client); // 建議放在finally塊中

CuratorFramework client = CuratorFrameworkFactory.builder().connectString("localhost:2181")
        .namespace("configCenter")   // 命名空間
        ...
        .build();
client.start();
client.create().forPath("/search/business/test", data);
//node was actually written to: "/configCenter/search/business/test"
...
CloseableUtils.closeQuietly(client); // 建議放在finally塊中

client.start();

// 判斷是否存在，Stat就是對znode所有屬性的一個映射，stat=null表示節(jié)點不存在
Stat stat = client.checkExists().forPath("/search/business/test");

// 查詢子節(jié)點
List<String> childNodes = client.getChildren()
        .forPath("/search/business/test"));

// 創(chuàng)建節(jié)點
client.create().creatingParentsIfNeeded() // 若創(chuàng)建節(jié)點的父節(jié)點不存在則先創(chuàng)建父節(jié)點再創(chuàng)建子節(jié)點
        .withMode(CreateMode.PERSISTENT) // 創(chuàng)建的是持久節(jié)點
        .withACL(Ids.OPEN_ACL_UNSAFE) // 默認匿名權(quán)限,權(quán)限scheme id:'world,'anyone,:cdrwa
        .forPath("/search/business/test","1".getBytes());
// 更新節(jié)點數(shù)據(jù)
client.setData()
		.withVersion(2) // 樂觀鎖
		.forPath("/search/business/test","0".getBytes());

// 讀取節(jié)點數(shù)據(jù)
Stat stat = new Stat(); // Stat就是對znode所有屬性的一個映射，stat=null表示節(jié)點不存在
String re = new String(client.getData()
		.storingStatIn(stat) // 在獲取節(jié)點內(nèi)容的同時把狀態(tài)信息存入Stat對象，如果不寫的話只會讀取節(jié)點數(shù)據(jù)
        .forPath("/search/business/test"));

// 刪除節(jié)點
client.delete()
        .guaranteed() // 保障機制，若未刪除成功，只要會話有效會在后臺一直嘗試刪除
        .deletingChildrenIfNeeded() // 若當前節(jié)點包含子節(jié)點，子節(jié)點也刪除
        .withVersion(2) // 指定版本號
        .forPath("/search/business/test");

// watcher事件,使用usingWatcher的時候,監(jiān)聽只會觸發(fā)一次，監(jiān)聽完畢后就銷毀
client.getData()
		.usingWatcher(new CuratorWatcher() {
			@Override
			public void process(WatchedEvent event) throws Exception {
				logger.info("觸發(fā)watcher, path:{}", event.getPath());
			}
		})
		.forPath("/search/business/test");

// watcher事件, NodeCache一次注冊N次監(jiān), 缺點:沒法監(jiān)聽當前節(jié)點增刪改操作,所以引出了PathChildrenCache
final NodeCache nodeCache = new NodeCache(client, "/search/business/test");
nodeCache.start(true); // 當zkServer與客戶端鏈接的時候, NodeCache會把zk數(shù)據(jù)緩存到我們本地
if (nodeCache.getCurrentData() != null) {
	logger.info("節(jié)點初始化數(shù)據(jù)為:{}", new String(nodeCache.getCurrentData().getData()));
} else {
	logger.info("節(jié)點初始化數(shù)據(jù)為空");
}
nodeCache.getListenable().addListener(new NodeCacheListener() {
	@Override
	public void nodeChanged() throws Exception {
		if (nodeCache.getCurrentData() != null) {
			String re = new String(nodeCache.getCurrentData().getData());
			logger.info("節(jié)點路徑:{}, 節(jié)點數(shù)據(jù):{}", nodeCache.getCurrentData().getPath(), re);
		} else {
			logger.info("當前節(jié)點被刪除了");
		}
	}
});

// 監(jiān)聽父節(jié)點以下所有的子節(jié)點, 當子節(jié)點發(fā)生變化的時候(增刪改)都會監(jiān)聽到
// 為子節(jié)點添加watcher事件
// PathChildrenCache監(jiān)聽數(shù)據(jù)節(jié)點的增刪改
final PathChildrenCache childrenCache = new PathChildrenCache(client, "/search", true);
// NORMAL:異步初始化, BUILD_INITIAL_CACHE:同步初始化, POST_INITIALIZED_EVENT:異步初始化,初始化之后會觸發(fā)事件
childrenCache.start(PathChildrenCache.StartMode.POST_INITIALIZED_EVENT);
List<ChildData> childDataList = childrenCache.getCurrentData(); // 當前數(shù)據(jù)節(jié)點的子節(jié)點數(shù)據(jù)列表
childrenCache.getListenable().addListener(new PathChildrenCacheListener() {
	@Override
	public void childEvent(CuratorFramework client, PathChildrenCacheEvent event) throws Exception {
		if (event.getType().equals(PathChildrenCacheEvent.Type.INITIALIZED)) {
			logger.info("子節(jié)點初始化ok..");
		} else if (event.getType().equals(PathChildrenCacheEvent.Type.CHILD_ADDED)) {
			logger.info("添加子節(jié)點, path:{}, data:{}", event.getData().getPath(), event.getData().getData());
		} else if (event.getType().equals(PathChildrenCacheEvent.Type.CHILD_REMOVED)) {
			logger.info("刪除子節(jié)點, path:{}", event.getData().getPath());
		} else if (event.getType().equals(PathChildrenCacheEvent.Type.CHILD_UPDATED)) {
			logger.info("修改子節(jié)點, path:{}, data:{}", event.getData().getPath(), event.getData().getData());
		}
	}
});


CloseableUtils.closeQuietly(client);//建議放在finally塊中

client.start();

// 開啟事務
CuratorTransaction transaction = client.inTransaction();
Collection<CuratorTransactionResult> results = transaction.create().forPath("/curator/1", "0".getBytes())
        .and().setData().forPath("/curator/2", "-1".getBytes())
        .and().delete().forPath("/curator/3")
        .and().commit();

CloseableUtils.closeQuietly(client);//建議放在finally塊中

/**
 * 本類基于leaderSelector實現(xiàn),所有存活的client會公平的輪流做leader
 * 如果不想頻繁的變化Leader，需要在takeLeadership方法里阻塞leader的變更！ 或者使用 {@link}
 * LeaderLatchClient
 */
public class LeaderSelectorClient extends LeaderSelectorListenerAdapter implements Closeable {
    private static final Log log = LogFactory.getLog(LeaderSelectorClient.class);
    private final String name;
    private final LeaderSelector leaderSelector;
    private final String PATH = "/leaderselector";

    public LeaderSelectorClient(CuratorFramework client, String name) {
        this.name = name;
        leaderSelector = new LeaderSelector(client, PATH, this);
        leaderSelector.autoRequeue();
    }
    public void start() throws IOException {
        leaderSelector.start();
    }
    @Override
    public void close() throws IOException {
        leaderSelector.close();
    }
    /**
     * client成為leader后，會調(diào)用此方法
     */
    @Override
    public void takeLeadership(CuratorFramework client) throws Exception {
        int waitSeconds = (int) (5 * Math.random()) + 1;
        log.info(name + "是當前的leader");
        try {
            Thread.sleep(TimeUnit.SECONDS.toMillis(waitSeconds));
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        } finally {
            log.info(name + "讓出領導權(quán)\n");
        }
    }
}