Zookeeper之javaAPI的使用

Java程序操作Zookeeper

1.创建java项目并导入相关jar包

主要jar包在主目录下项目需要的相关依赖的jar包在zookeeper的解压文件的lib目录下就有将这几个jar包导入项目中

<dependency>
	<groupId>org.apache.zookeeper</groupId>
	<artifactId>zookeeper</artifactId>
	<version>3.4.6</version>
	<type>pom</type>
</dependency>
<dependency>
	<groupId>com.github.sgroschupf</groupId>
	<artifactId>zkclient</artifactId>
	<version>0.1</version>
</dependency>
<dependency>
	<groupId>junit</groupId>
	<artifactId>junit</artifactId>
	<version>4.12</version>
</dependency>

API简单使用

2.1配置Zookeeper对象

	// zookeeper的服务器地址,配置conf是用主机名，这里一样
	private String connectString ="zek00:2181,zek01:2181,zek02:2181";
	// 连接超时时间
	private int sessionTimeout = 2000;

	private ZooKeeper zk = null;

	/**
	 * 设置zookeeper对象
	 * @throws IOException
	 */
	@Before
	public void setZookeeper() throws IOException {

		zk = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
			/**
			 * 事件触发的回调方法
			 */
			@Override
			public void process(WatchedEvent event) {

			}
		});
		System.out.println("---"+zk);
	}

常用API操作

/**
 * create 方法参数
 *    第一个参数 路径
 *    第二个参数  值  bytes
 *    第三个参数  对节点的访问控制
 *    第四个参数  节点的类型 短暂  永久  序号
 * @throws KeeperException
 * @throws InterruptedException
 */
@Test
public void create() throws KeeperException, InterruptedException {
	String path = zk.create("/app3", "123".getBytes(),
			Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
	System.out.println(path);
}
/**
 * 判断节点是否存在
 * @throws InterruptedException
 * @throws KeeperException
 */
@Test
public void exist() throws KeeperException, InterruptedException{
	// 设置为 true 会调用 zk中的监听器
	Stat stat = zk.exists("/app1", true);
	if(stat!=null){

		System.out.println("存在。。。。"+stat.getDataLength());
	}else{
		System.out.println("不存在。。。");
	}
}
/**
 * 获取子节点
 * @throws InterruptedException
 * @throws KeeperException
 */
@Test
public void getChilren() throws KeeperException, InterruptedException{
	List<String> list = zk.getChildren("/", true);
	for (String s : list) {
		System.out.println(s);
	}
}

/**
 * 获取节点的内容
 * @throws InterruptedException
 * @throws KeeperException
 */
@Test
public void getData() throws KeeperException, InterruptedException{

	byte[] b = zk.getData("/app1", false, null );
	System.out.println(new String(b));
}

/**
 * 修改节点内容
 * 	  version -1 自动维护
 * @throws InterruptedException
 * @throws KeeperException
 */
@Test
public void setData() throws KeeperException, InterruptedException{
	Stat s = zk.setData("/app1", "test".getBytes(), -1);
}
/**
 * 删除节点
 *    非空节点删除不掉
 * @throws InterruptedException
 * @throws KeeperException
 */
@Test
public void deleteNode() throws InterruptedException, KeeperException{
	zk.delete("/app1", -1);
}

监听器的使用

@Before
public static void setUpBeforeClass() throws Exception {
	zk = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
		/**
		 * 监听器
		 */
		@Override
		public void process(WatchedEvent event) {
			System.out.println("事件触发...");
		}
	});
}


/**
 * 获取子节点
 * getChildren(path,watch?)监听的事件是：节点下的子节点增减变化事件
 * @throws InterruptedException
 * @throws KeeperException
 */
@Test
public void getChilren() throws KeeperException, InterruptedException{
	List<String> list = zk.getChildren("/", new Watcher() {

		@Override
		public void process(WatchedEvent event) {
			// TODO Auto-generated method stub
			System.out.println("监控节点下的子节点被改变..."+event.getPath());
		}
	});
	for (String s : list) {
		System.out.println(s);
	}
	Thread.sleep(Long.MAX_VALUE);
}

/**
 * 获取节点的内容
 * getData(path,watch?)监听的事件是：节点数据变化事件
 * @throws InterruptedException
 * @throws KeeperException
 */
@Test
public void getData() throws KeeperException, InterruptedException{

	byte[] b = zk.getData("/app1", new Watcher() {

		@Override
		public void process(WatchedEvent event) {
			System.out.println("--数据改变了--");

		}
	}, null );
	System.out.println(new String(b));
	Thread.sleep(Long.MAX_VALUE);
}