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This article will explain in detail how to update data on ZooKeeper Java client API. The content of the article is of high quality, so the editor shares it for you as a reference. I hope you will have a certain understanding of the relevant knowledge after reading this article.

Synchronously update data import java.util.concurrent.CountDownLatch;import org.apache.zookeeper.CreateMode;import org.apache.zookeeper.KeeperException;import org.apache.zookeeper.WatchedEvent;import org.apache.zookeeper.Watcher;import org.apache.zookeeper.Watcher.Event.KeeperState;import org.apache.zookeeper.Watcher.Event.EventType;import org.apache.zookeeper.ZooKeeper;import org.apache.zookeeper.ZooDefs.Ids;import org.apache.zookeeper.data.Stat Public class SetData_API_Sync_Usage implements Watcher {private static CountDownLatch connectedSemaphore = new CountDownLatch (1); private static ZooKeeper zk = null; public static void main (String [] args) throws Exception {String path = "/ titush-book2"; zk = new ZooKeeper ("202.201.purve2100", 5000, new SetData_API_Sync_Usage ()) ConnectedSemaphore.await (); zk.create (path, "1231" .getBytes (), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT); zk.getData (path, true, null); Stat stat = zk.setData (path, "4561" .getBytes (),-1) System.out.println (stat.getCzxid () + "," + stat.getMzxid () + "," + stat.getVersion ()); Stat stat2 = zk.setData (path, "4561" .getBytes (), stat.getVersion ()); System.out.println (stat2.getCzxid () + "," + stat2.getMzxid () + "," + stat2.getVersion () Try {zk.setData (path, "456" .getBytes (), stat.getVersion ());} catch (KeeperException e) {System.out.println ("Error:" + e.code () + "," + e.getMessage ());} Thread.sleep (Integer.MAX_VALUE) @ Override public void process (WatchedEvent event) {if (KeeperState.SyncConnected = = event.getState ()) {if (EventType.None = = event.getType () & & null = = event.getPath ()) {connectedSemaphore.countDown ();}

Result printing

111PerErrorCode = BadVersion for / titush-book2

The current latest version of the data node is represented as-1, and the first version is represented as 0.

The version is updated to 1 after the first setting of data and to 2 after the second setting.

An error occurred when updating with version 1 for the third time, because the version at this time was already 2.

This is the use of optimistic locks, and stat.getVersion () is used for write checking.

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