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本文主要贴出通过zookeeper的客户端类访问zookeeper的示例，以及其它第三方更高层次的封装的客户端使用。
1.通过org.apache.zookeeper.ZooKeeper来操作zookeeper服务
有关zookeeper服务的部署参见文：http://www.iyunv.com/thread-98262-1-1.html 下文将有代码示例展示通过编码方式在应用中启动zookeeper服务。
ZooKeeper类对zookeeper服务的简单操作示例代码如下：
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| package secondriver.dubbo.client;
import org.apache.zookeeper.*;
import org.apache.zookeeper.data.Stat;
import java.io.IOException;
import java.util.List;
import java.util.concurrent.TimeUnit;
/**
* Author : secondriver
*/
public class TestZookeeper {
public static void main(String[] args) throws IOException, KeeperException, InterruptedException {
//创建zookeeper客户端
ZooKeeper zooKeeper = new ZooKeeper("192.168.88.153:2181", 1000, new Watcher() {
@Override
public void process(WatchedEvent event) {
System.out.println("EventType:" + event.getType().name());
}
});
//获取"/" node下的所有子node
List<String> znodes = zooKeeper.getChildren("/", true);
for (String path : znodes) {
System.out.println(path);
}
//创建开放权限的持久化node "/test"
String rs = zooKeeper.create("/test", "test".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode
.PERSISTENT);
System.out.println(rs);
//同步获取"/test" node的数据
Stat stat = new Stat();
byte[] data = zooKeeper.getData("/test", true, stat);
System.out.println("value=" + new String(data));
System.out.println(stat.toString());
//异步获取"/test" node的数据
zooKeeper.getData("/test", true, new AsyncCallback.DataCallback() {
@Override
public void processResult(int rc, String path, Object ctx, byte[] data, Stat stat) {
System.out.println(rc);
System.out.println(path);
System.out.println(ctx);
System.out.printf(new String(data));
System.out.println(stat.toString());
}
}, "Object ctx ..(提供的外部对象)");
TimeUnit.SECONDS.sleep(10);
zooKeeper.close();
}
}
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上述代码依赖zookeeper包
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| <dependency>
<groupId>org.apache.zookeeper</groupId>
<artifactId>zookeeper</artifactId>
<version>3.4.6</version>
</dependency>
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2.通过zkclient操作zookeeper服务
zkclient github: https://github.com/sgroschupf/zkclient
后续有二次开发的版本：
项目： https://github.com/adyliu/zkclient
文档： https://github.com/adyliu/zkclient/wiki/tutorial
下文代码示例使用sgroschupf/zkclient,依赖Zookeeper包。
maven sgroschupf/zkclient
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| <dependency>
<groupId>com.101tec</groupId>
<artifactId>zkclient</artifactId>
<version>0.5</version>
</dependency>
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应用内server+client:
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| package secondriver.dubbo.server;
import org.I0Itec.zkclient.IDefaultNameSpace;
import org.I0Itec.zkclient.ZkClient;
import org.I0Itec.zkclient.ZkServer;
import org.apache.zookeeper.CreateMode;
import java.io.IOException;
/**
* Author : secondriver
*/
public class TestI0ItecZk {
public static void main(String[] args) throws IOException {
//Server + Client
ZkServer zkServer = new ZkServer("D:/data", "D:/log", new IDefaultNameSpace() {
@Override
public void createDefaultNameSpace(ZkClient zkClient) {
zkClient.create("/default", "defalut-name-space", CreateMode.PERSISTENT);
}
});
zkServer.start();
ZkClient zkClient = zkServer.getZkClient();
boolean exists = zkClient.exists("/default");
if (exists) {
System.out.println("default name space init create succeed.");
} else {
System.out.println("default name space init create failed.");
}
System.in.read();
zkClient.close();
zkServer.shutdown();
}
}
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应用外部署server,使用client访问：
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| package secondriver.dubbo.server;
import org.I0Itec.zkclient.ZkClient;
import java.util.List;
/**
* Author : secondriver
*/
public class TestZkClient {
public static void main(String[] args) {
//Only use client
ZkClient zkc = new ZkClient("192.168.88.153:2181,192.168.88.153:2182,192.168.88.153:2183");
List<String> childrens = zkc.getChildren("/");
for (String child : childrens) {
System.out.println(child);
}
}
}
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下文代码示例使用adyliu/zkclient,同样依赖Zookeeper包，启动Zookeeper服务并做操作。
maven adyliu/zkclient:
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| <dependency>
<groupId>com.github.adyliu</groupId>
<artifactId>zkclient</artifactId>
<version>2.1.1</version>
</dependency>
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| package secondriver.dubbo.server;
import com.github.zkclient.*;
import java.io.IOException;
import java.util.List;
/**
* Author : secondriver
*/
public class TestZk {
public static void main(String[] args) throws IOException {
String home = System.getProperty("user.home");
//创建zookeeper服务并启动
ZkServer zkServer = new ZkServer(home + "/zookeeper/data", home + "/zookeeper/log", 2181);
zkServer.start();
//方式一
// ZkClient zkClient = new ZkClient("127.0.0.1:2181", 1000);
//方式二
ZkClient zkClient = zkServer.getZkClient();
String path = "/test" + Math.random();
//数据监听
final IZkDataListener dataListener = new IZkDataListener() {
@Override
public void handleDataChange(String dataPath, byte[] data) throws Exception {
System.out.println(dataPath + " data change");
}
@Override
public void handleDataDeleted(String dataPath) throws Exception {
}
};
//结点（node）监听
final IZkChildListener childListener = new IZkChildListener() {
@Override
public void handleChildChange(String parentPath, List<String> currentChildren) throws Exception {
System.out.println(parentPath + " parentPath");
for (String path : currentChildren) {
System.out.println(path);
}
}
};
//为指定node添加监听
zkClient.subscribeDataChanges(path, dataListener);
zkClient.subscribeChildChanges("/", childListener);
//zkclient操作Zookeeper服务
///检测node是否存在
if (zkClient.exists("/zookeeper")) {
System.out.println("Exist zookeeper path");
} else {
System.out.println("Not Exist zookeeper path");
}
zkClient.createPersistent(path, path.getBytes());
byte[] before = zkClient.readData(path);
System.out.println("before:" + new String(before));
//以原子的方式更新指定的path node的数据
zkClient.cas(path, new IZkClient.DataUpdater() {
@Override
public byte[] update(byte[] currentData) {
return new String(currentData).concat(new String(" updated")).getBytes();
}
});
byte[] after = zkClient.readData(path);
System.out.println("after:" + new String(after));
//取消指定path node的数据监听
zkClient.unsubscribeDataChanges(path, dataListener);
zkClient.writeData(path, "new-data".getBytes());
byte[] dataBytes = zkClient.readData(path);
String data = new String(dataBytes);
System.out.println(path + " data :" + data);
System.in.read();
zkClient.close();
zkServer.shutdown();
}
}
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3. Zookeeper客户端和富Zookeeper框架之curator
github: https://github.com/Netflix/curator
已成为apache项目：http://curator.apache.org
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