[英]Good Zookeeper Hello world Program with Java client
我試圖在我們的項目中使用Zookeeper。 可以運行服務器。。甚至可以使用zkcli.sh對其進行測試。。都很好。。但是找不到適合我使用Java連接到該服務器的好教程! 我在Java API中需要的只是一個方法
public String getServiceURL ( String serviceName )
我嘗試了https://cwiki.apache.org/confluence/display/ZOOKEEPER/Index- >對我不好。
http://zookeeper.apache.org/doc/trunk/javaExample.html :還可以; 但是無法清楚地理解概念! 我覺得不好解釋。
最后,這是我想到的最簡單,最基本的程序,它將幫助您使用ZooKeeper“入門”:
package core.framework.zookeeper;
import java.util.Date;
import java.util.List;
import java.util.concurrent.CountDownLatch;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.Watcher.Event.KeeperState;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.ZooKeeper;
public class ZkConnect {
private ZooKeeper zk;
private CountDownLatch connSignal = new CountDownLatch(0);
//host should be 127.0.0.1:3000,127.0.0.1:3001,127.0.0.1:3002
public ZooKeeper connect(String host) throws Exception {
zk = new ZooKeeper(host, 3000, new Watcher() {
public void process(WatchedEvent event) {
if (event.getState() == KeeperState.SyncConnected) {
connSignal.countDown();
}
}
});
connSignal.await();
return zk;
}
public void close() throws InterruptedException {
zk.close();
}
public void createNode(String path, byte[] data) throws Exception
{
zk.create(path, data, Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
}
public void updateNode(String path, byte[] data) throws Exception
{
zk.setData(path, data, zk.exists(path, true).getVersion());
}
public void deleteNode(String path) throws Exception
{
zk.delete(path, zk.exists(path, true).getVersion());
}
public static void main (String args[]) throws Exception
{
ZkConnect connector = new ZkConnect();
ZooKeeper zk = connector.connect("54.169.132.0,52.74.51.0");
String newNode = "/deepakDate"+new Date();
connector.createNode(newNode, new Date().toString().getBytes());
List<String> zNodes = zk.getChildren("/", true);
for (String zNode: zNodes)
{
System.out.println("ChildrenNode " + zNode);
}
byte[] data = zk.getData(newNode, true, zk.exists(newNode, true));
System.out.println("GetData before setting");
for ( byte dataPoint : data)
{
System.out.print ((char)dataPoint);
}
System.out.println("GetData after setting");
connector.updateNode(newNode, "Modified data".getBytes());
data = zk.getData(newNode, true, zk.exists(newNode, true));
for ( byte dataPoint : data)
{
System.out.print ((char)dataPoint);
}
connector.deleteNode(newNode);
}
}
如果您正在尋找Java實例,那么此博客文章Zookeeper Java API examples包括一些很好的實例。 Zookeeper還提供了一個非常易於使用的客戶端API庫(C和Java)。
Zookeeper是最好的開源服務器和服務之一,可幫助可靠地協調分布式過程。 Zookeeper是一種CP系統(請參閱CAP定理),可提供一致性和分區容限。 Zookeeper狀態跨所有點的復制使其成為最終一致的分布式服務。
這篇文章幾乎包含了與Zookeeper交互所需的所有操作。 https://www.tutorialspoint.com/zookeeper/zookeeper_api.htm
如果您在AWS上; 現在,我們可以創建內部ELB,它支持基於URI的重定向。使用已經引入的高可用性,它可以真正解決此問題。
這就是您所能獲得的最簡單的方法。 我正在構建一個工具,該工具將使用ZK鎖定正在處理的文件(因此為類名):
package mypackage;
import java.io.IOException;
import java.util.List;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.Watcher;
public class ZooKeeperFileLock {
public static void main(String[] args) throws IOException, KeeperException, InterruptedException {
String zkConnString = "<zknode1>:2181,<zknode2>:2181,<zknode3>:2181";
ZooKeeperWatcher zkWatcher = new ZooKeeperWatcher();
ZooKeeper client = new ZooKeeper(zkConnString, 10000, zkWatcher);
List<String> zkNodes = client.getChildren("/", true);
for(String node : zkNodes) {
System.out.println(node);
}
}
public static class ZooKeeperWatcher implements Watcher {
@Override
public void process(WatchedEvent event) {
}
}
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.