Java API operation of zookeeper

Homo sapiens 2021-01-21 20:52:17
java api operation zookeeper


This blog brings you a long-awaited story about ZooKeeper Of JavaAPI operation !!!

Before I show you the code , Let's first introduce a few classes we need to use !

  • org.apache.zookeeper.Zookeeper Zookeeper Is in Java In the client main class , Responsible for establishing and zookeeper Session of cluster , And provide methods to operate .
  • org.apache.zookeeper.Watcher Watcher Interface represents a standard event handler , It defines the logic associated with event notification , contain KeeperState and EventType Two enumeration classes , They represent notification state and event type respectively , At the same time, the callback method of the event is defined :process(WatchedEvent event).

process The method is Watcher A callback method in the interface , When ZooKeeper Send a Watcher When the event is notified , The client will respond to the process Method to call back , So as to realize the handling of events .

Basic use

Then officially enter JavaAPI Normal use of

First, we need to build java maven project , introduce maven pom coordinate

<dependency>
<groupId>org.apache.zookeeper</groupId>
<artifactId>zookeeper</artifactId>
<version>3.4.9</version>
</dependency>

Basic operation case :

public static void main(String[] args) throws Exception {
// initialization ZooKeeper example (zk Address 、 Session timeout , Consistent with the system default 、watcher)
ZooKeeper zk = new ZooKeeper("node-1:2181,node-2:2181", 30000, new Watcher() {
@Override
public void process(WatchedEvent event) {
System.out.println(" The event type is :" + event.getType());
System.out.println(" The path of the event :" + event.getPath());
System.out.println(" Notification status is :" +event.getState());
}
});
zk.create("/myGirls", " erotogenic ".getBytes("UTF-8"), Ids.OPEN_ACL_UNSAFE,
CreateMode.PERSISTENT);
zk.close();

More examples :

public static void main(String[] args) throws Exception {
// initialization ZooKeeper example (zk Address 、 Session timeout , Consistent with the system default 、watcher)
ZooKeeper zk = new ZooKeeper("node-21:2181,node-22:2181", 30000, new Watcher() {
@Override
public void process(WatchedEvent event) {
System.out.println(" The event type is :" + event.getType());
System.out.println(" The path of the event :" + event.getPath());
System.out.println(" Notification status is :" +event.getState());
}
});
// Create a directory node
zk.create("/testRootPath", "testRootData".getBytes(), Ids.OPEN_ACL_UNSAFE,
CreateMode.PERSISTENT);
// Create a subdirectory node
zk.create("/testRootPath/testChildPathOne", "testChildDataOne".getBytes(),
Ids.OPEN_ACL_UNSAFE,CreateMode.PERSISTENT);
System.out.println(new String(zk.getData("/testRootPath",false,null)));
// Take out the list of subdirectory nodes
System.out.println(zk.getChildren("/testRootPath",true));
// Modify subdirectory node data
zk.setData("/testRootPath/testChildPathOne","modifyChildDataOne".getBytes(),-1);
System.out.println(" Directory node status :["+zk.exists("/testRootPath",true)+"]");
// Create another subdirectory node
zk.create("/testRootPath/testChildPathTwo", "testChildDataTwo".getBytes(),
Ids.OPEN_ACL_UNSAFE,CreateMode.PERSISTENT);
System.out.println(new String(zk.getData("/testRootPath/testChildPathTwo",true,null)));
// Delete subdirectory node
zk.delete("/testRootPath/testChildPathTwo",-1);
zk.delete("/testRootPath/testChildPathOne",-1);
// Delete the parent directory node
zk.delete("/testRootPath",-1);
zk.close();
}

because Java API The operation is more basic , In addition, the key points have corresponding notes , So we won't elaborate on Xiaojun here !

So that's all for this sharing , If you have any doubts, you can leave a message in the comment area or send a private message to Xiaojun . in addition , Those who benefit or are interested in big data technology can pay attention to small bacteria ~ Pay attention to , Xiaobai is not lost !

Participation of this paper Tencent cloud media sharing plan , You are welcome to join us , share .

版权声明
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https://javamana.com/2021/01/20210121205052140v.html

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