使用Java操作Zookeeper
目录
一、介绍
2.1、导入依赖
2.2、连接zk集群
2.3、操作数据操作
3.1、导入依赖
3.2、使用示例
一、介绍
这里主要记录通过Java调用API来操作Zookeeper集群的数据，对于zookeeper集群的搭建或者命令，可以参考：
目前接触到的Java操作Zookeeper，有两套API，一套是zookeeper官方提供的（zookeeper），另外一套是封装了官方API的API（zkClient），从描述上来看，就知道，官方的API可能不是那么好用，不然也不会在封装。
二、zookeeper API
2.1、导入依赖
使用zookeeper官方api的时候，请保证jar包的版本，和zk集群中zk的版本相同
<!-- https://mvnrepository.com/artifact/org.apache.zookeeper/zookeeper -->
<dependency>
<groupId>org.apache.zookeeper</groupId>
<artifactId>zookeeper</artifactId>
<version>3.4.7</version>
</dependency>
2.2、连接zk集群
下面是代码示例，两种形式（分别使用匿名类和Lambda表达式）：
package cn.ganlixin.zk;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;
import org.junit.Test;
import java.io.IOException;
public class ZookeeperDemo {
@Test
public void connectZkCluster() throws IOException, KeeperException, InterruptedException {
// 构造方法
// ZooKeeper(String connectString, int sessionTimeout, Watcher watcher)
// 匿名对象形式
ZooKeeper zooKeeper = new ZooKeeper(
"192.168.1.3:2181,192.168.1.4:2181,192.168.1.5:2181",
20000,
new Watcher() {
@Override
public void process(WatchedEvent watchedEvent) {
// 发生变更的节点路径
String path = watchedEvent.getPath();
System.out.println("path:" + path);
// 通知状态
Watcher.Event.KeeperState state = watchedEvent.getState();
System.out.println("KeeperState:" + state);
// 事件类型
Watcher.Event.EventType type = watchedEvent.getType();
System.out.println("EventType:" + type);
}
}
);
// 关闭连接
zooKeeper.close();
// Lamdba形式
ZooKeeper zk = new ZooKeeper(
"192.168.1.3:2181,192.168.1.4:2181,192.168.1.5:2181",
20000,
watchedEvent -> {
// 发生变更的节点路径
String path = watchedEvent.getPath();
System.out.println("path:" + path);
// 通知状态
Watcher.Event.KeeperState state = watchedEvent.getState();
System.out.println("KeeperState:" + state);
// 事件类型
Watcher.Event.EventType type = watchedEvent.getType();
System.out.println("EventType:" + type);
}
);
zk.close();
}
}
运行上面的代码，控制台输出如下（输出了两遍，是因为创建了两次连接）
path:null KeeperState:SyncConnected EventType:None path:null KeeperState:SyncConnected EventType:None
2.3、操作数据操作
操作Zk中的数据，方式也很简单，只需要使用创建的zk连接，调用对应的方法即可（方法名与zk命令行中命令相同）
package cn.ganlixin.zk;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.ZooDefs;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.Stat;
import org.junit.Test;
import java.io.IOException;
public class ZookeeperDemo {
@Test
public void manageData() throws KeeperException, InterruptedException, IOException {
// 创建zk连接
ZooKeeper zk = new ZooKeeper(
"192.168.1.3:2181,192.168.1.4:2181,192.168.1.5:2181",
20000,
null
);
// 创建节点
zk.create("/abc", "123".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
// 获取节点数据
// getData(String path, boolean watch, Stat stat);
Stat stat = new Stat();
byte[] data = zk.getData("/abc", false, stat);
System.out.println(new String(data)); // 数据内容 123
System.out.println(stat.getDataLength()); // 节点状态（数据长度） 3
// 对/abc进行watch
zk.getData("/abc",
watchedEvent -> {
System.out.println("path:" + watchedEvent.getPath());
System.out.println("KeeperState:" + watchedEvent.getState());
System.out.println("EventType:" + watchedEvent.getType());
},
null);
// 设置节点数据
// setData(String path, byte[] data, int version)
// 指定version为-1，表示不关心版本
zk.setData("/abc", "456".getBytes(), -1);
// 设置两次，第二次不会触发通知
zk.setData("/abc", "789".getBytes(), -1);
// 阻塞，以等待通知
Thread.sleep(1000);
zk.close();
}
}
上面的程序，运行输出结果如下：
123 3 path:/abc KeeperState:SyncConnected EventType:NodeDataChanged
可以看到，只显示了一次通知，和与预期相符。
三、zkClient API
因为Zookeeper API比较复杂，使用并不方便，所以出现了ZkClient，ZkClient对Zookeeper API进行了封装，利用ZkClient可以更加方便地对Zookeeper进行操作。
3.1、导入依赖
因为zkClient是对zookeeper的再封装，所以需要注意zkClient中zookeeper的版本与zk集群的版本相同，可以在maven仓库中查看对应关系
<!-- https://mvnrepository.com/artifact/com.101tec/zkclient -->
<dependency>
<groupId>com.101tec</groupId>
<artifactId>zkclient</artifactId>
<version>0.10</version>
</dependency>
3.2、使用示例
下面是个简单的示例：
package cn.ganlixin.zk;
import org.I0Itec.zkclient.IZkChildListener;
import org.I0Itec.zkclient.IZkStateListener;
import org.I0Itec.zkclient.ZkClient;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.Watcher;
import org.junit.Test;
import java.util.List;
public class ZkClientDemo {
@Test
public void testConn() throws InterruptedException {
ZkClient zkClient = new ZkClient(
"192.168.1.3:2181,192.168.1.4:2181,192.168.1.5:2181",
20000
);
// 创建节点
zkClient.createPersistent("/abc", "hello");
zkClient.createEphemeral("/xyz", "world");
zkClient.create("/opq", "world", CreateMode.EPHEMERAL_SEQUENTIAL);
String data = zkClient.readData("/abc");
System.out.println(data);
// 监听状态变化
zkClient.subscribeStateChanges(new IZkStateListener() {
@Override
public void handleStateChanged(Watcher.Event.KeeperState keeperState) throws Exception {
System.out.println("state:" + keeperState);
}
@Override
public void handleNewSession() throws Exception {
System.out.println("new session");
}
@Override
public void handleSessionEstablishmentError(Throwable throwable) throws Exception {
throwable.printStackTrace();
}
});
// 监听子节点发生变化
zkClient.subscribeChildChanges("/", new IZkChildListener() {
@Override
public void handleChildChange(String path, List<String> list) throws Exception {
System.out.println("watch path:" + path);
// 输出所有子节点
list.forEach(str -> {
System.out.println(str);
});
}
});
Thread.sleep(100000);
}
}
如需转载，请注明文章出处，谢谢！！！
