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ZooKeeper官方提供了Java API#xff0c;可以通过Java代码来连接zookeeper服务进行操作。可以连接、创建节点、获取节点数据、监听节点变化等操作#xff0c;具体有以下几个重要的类#xff1a;
ZooKeeper#xff1a;ZooKeeper类是Java API的核心类#xff0c;用于与…API
ZooKeeper官方提供了Java API可以通过Java代码来连接zookeeper服务进行操作。可以连接、创建节点、获取节点数据、监听节点变化等操作具体有以下几个重要的类
ZooKeeperZooKeeper类是Java API的核心类用于与ZooKeeper服务器建立连接并提供了一系列方法来操作ZooKeeper的节点。WatcherWatcher是ZooKeeper的一个回调接口当节点发生变化时会调用相应的方法进行通知。CreateModeCreateMode枚举类定义了节点的类型包括永久节点、临时节点、顺序节点和临时顺序节点。StatStat类表示节点的元数据信息比如修改版本、数据长度、子节点数量等。
添加依赖
dependencygroupIdorg.apache.zookeeper/groupIdartifactIdzookeeper/artifactIdversion3.7.2/version
/dependency操作例子
String host localhost:2181;
//建立连接
zooKeeper new ZooKeeper(host, 2000, null);
String path /test;
Watcher watcher new Watcher() {Overridepublic void process(WatchedEvent watchedEvent) {System.out.println(Node changed: watchedEvent.getPath());System.out.println(watchedEvent);}
};
//获取节点状态 如果不存在返回null
Stat stat zooKeeper.exists(path, false);
if(null ! stat){System.out.println(stat.getCzxid()-stat.getAversion());
}//创建节点 包含版本、时间、数据长度等信息
zooKeeper.create(path,123.getBytes(),ZooDefs.Ids.OPEN_ACL_UNSAFE,CreateMode.PERSISTENT);
//添加watcher
zooKeeper.addWatch(path, watcher, AddWatchMode.PERSISTENT);//获取节点数据
byte[] data zooKeeper.getData(path, false, null);
System.out.println(new String(data));zooKeeper.create(path/1,child1.getBytes(),ZooDefs.Ids.OPEN_ACL_UNSAFE,CreateMode.PERSISTENT);
//获取子节点
ListString children zooKeeper.getChildren(path, false);
System.out.println(childs size:children.size());
//删除子节点
zooKeeper.delete(path/1,-1);
zooKeeper.close();zkClient
zkClient封装了zookeeper的官方api简化了一些繁琐的操作并提供了一些额外的功能提高了开发效.
添加依赖
dependencygroupIdcom.101tec/groupIdartifactIdzkclient/artifactIdversion0.11/version
/dependencyzkclient对节点数据的操作进行了序列化 这里先准备一个string类型的序列化类。需要实现ZkSerializer接口
public class ZkStringSerializer implements ZkSerializer {Overridepublic byte[] serialize(Object o) throws ZkMarshallingError {return String.valueOf(o).getBytes();}Overridepublic Object deserialize(byte[] bytes) throws ZkMarshallingError {return new String(bytes);}
}基本操作
ZkClient zkClient new ZkClient(localhost:2181);
//自定义序列化 否则报错
zkClient.setZkSerializer(new ZkStringSerializer());
String path /test;
//判断节点是否存在
boolean exist zkClient.exists(path);
System.out.println(exist);
if(!exist){//创建节点zkClient.create(path,123, CreateMode.PERSISTENT);
}
//读取节点数据
System.out.println((String) zkClient.readData(path));
zkClient.writeData(path,456);//设置节点数据
System.out.println((String) zkClient.readData(path));
zkClient.delete(path);//删除节点zkClient.close();节点变化事件
String path /test;
/*** 节点变化事件* 只监听节点增减不监听数据变化事件*/
zkClient.subscribeChildChanges(path, new IZkChildListener() {Overridepublic void handleChildChange(String parentPath, ListString children) throws Exception {System.out.println(节点parentPath发生变化);System.out.println(children);}
});
//节点操作观察handleChildChange接收到对应事件
Thread.sleep(2000);
zkClient.createPersistent(path);
Thread.sleep(2000);
zkClient.createPersistent(path/child1);
Thread.sleep(2000);
zkClient.writeData(path/child1,123);
Thread.sleep(2000);
zkClient.delete(path/child1);
Thread.sleep(2000);
zkClient.delete(path);
Thread.sleep(100000);节点数据变化事件 String path /test;/*** 节点变化事件,只检测当前节点感知不到其子节点* 节点被删除或节点数据变化*/zkClient.subscribeDataChanges(path, new IZkDataListener() {Overridepublic void handleDataChange(String s, Object o) throws Exception {System.out.println(节点s数据变为:o);}Overridepublic void handleDataDeleted(String s) throws Exception {System.out.println(节点s删除);}});Thread.sleep(2000);zkClient.createPersistent(path);Thread.sleep(2000);zkClient.createPersistent(path/child1);Thread.sleep(2000);zkClient.delete(path/child1);Thread.sleep(2000);zkClient.writeData(path,123);Thread.sleep(2000);zkClient.delete(path);Thread.sleep(100000);
}Curator
curator是另一个java连接zookeeper类库。功能更加强大。提供了连接重试、分布式锁、选举、队列等多种实际场景的用例。这里先简单搞个使用例子。
添加依赖
dependencygroupIdorg.apache.curator/groupIdartifactIdcurator-framework/artifactIdversion5.1.0/version
/dependencycurator-framework是基础的依赖一些特定的使用方式需要添加不同的依赖有curator-recipes、curator-x-discovery、curator-x-async等。
基本操作
//创建连接
CuratorFramework client CuratorFrameworkFactory.newClient(localhost:2181, new ExponentialBackoffRetry(1000, 3));
client.start();
String path /test;
client.checkExists().forPath(path);//判断是否存在
client.create().forPath(path, 123.getBytes());//创建节点
byte[] data client.getData().forPath(path);//获取数据
System.out.println(new String(data));
client.setData().forPath(path, 456.getBytes());//设置数据
client.delete().forPath(path);//删除节点client.close();节点监听
CuratorFramework client CuratorFrameworkFactory.newClient(localhost:2181, new ExponentialBackoffRetry(1000, 3));
client.start();
String path /test;
NodeCache nodeCache new NodeCache(client,path);
//添加监听
nodeCache.getListenable().addListener(new NodeCacheListener() {Overridepublic void nodeChanged() throws Exception {ChildData data nodeCache.getCurrentData();if (data ! null) {System.out.println(Node changed: data.getPath() , value: new String(data.getData()));} else {System.out.println(Node deleted: nodeCache.getPath());}}
});
nodeCache.start();
client.create().forPath(path);
client.setData().forPath(path, 123.getBytes());
client.delete().forPath(path);
client.close();这里NodeCache被标识Deprecated也不知道被什么方式代替了后面再研究。先简单使用。
