public class CreateGroupTest { private static String hosts = "192.168.1.8"; private static String groupName = "zoo"; private CreateGroup createGroup = null; /** * init * @throws InterruptedException * @throws KeeperException * @throws IOException */ @Before public void init() throws KeeperException, InterruptedException, IOException { createGroup = new CreateGroup(); createGroup.connect(hosts); } @Test public void testCreateGroup() throws KeeperException, InterruptedException { createGroup.create(groupName); } /** * 销毁资源 */ @After public void destroy() { try { createGroup.close(); createGroup = null; System.gc(); } catch (InterruptedException e) { e.printStackTrace(); } } }
由于zk对象的创建和销毁代码是可以复用的，所以这里我们把它分装成了接口：
/** * 连接的观察者，封装了zk的创建等 * @author leo * */ public class ConnectionWatcher implements Watcher { private static final int SESSION_TIMEOUT = 5000; protected ZooKeeper zk = null; private CountDownLatch countDownLatch = new CountDownLatch(1); public void process(WatchedEvent event) { KeeperState state = event.getState(); if(state == KeeperState.SyncConnected){ countDownLatch.countDown(); } } /** * 连接资源 * @param hosts * @throws IOException * @throws InterruptedException */ public void connection(String hosts) throws IOException, InterruptedException { zk = new ZooKeeper(hosts, SESSION_TIMEOUT, this); countDownLatch.await(); } /** * 释放资源 * @throws InterruptedException */ public void close() throws InterruptedException { if (null != zk) { try { zk.close(); } catch (InterruptedException e) { throw e; }finally{ zk = null; System.gc(); } } } }
7. Zookeeper删除Znode/** * 删除分组 * @author leo * */ public class DeleteGroup extends ConnectionWatcher { public void delete(String groupName) { String path = "/" + groupName; try { List<String> children = zk.getChildren(path, false); for(String child : children){ zk.delete(path + "/" + child, -1); } zk.delete(path, -1);//版本号为-1， } catch (KeeperException e) { e.printStackTrace(); } catch (InterruptedException e) { e.printStackTrace(); } } }
zk.delete(path,version)方法的第二个参数是znode版本号，如果提供的版本号和znode版本号一致才会删除这个znode，这样可以检测出对znode的修改冲突。通过将版本号设置为-1，可以绕过这个版本检测机制，无论znode的版本号是什么，都会直接将其删除。
测试类：
public class DeleteGroupTest { private static final String HOSTS = "192.168.1.137"; private static final String groupName = "zoo"; private DeleteGroup deleteGroup = null; @Before public void init() throws IOException, InterruptedException { deleteGroup = new DeleteGroup(); deleteGroup.connection(HOSTS); } @Test public void testDelete() throws IOException, InterruptedException, KeeperException { deleteGroup.delete(groupName); } @After public void destroy() throws InterruptedException { if(null != deleteGroup){ try { deleteGroup.close(); } catch (InterruptedException e) { throw e; }finally{ deleteGroup = null; System.gc(); } } } } View Code 8. Zookeeper的相关操作
ZooKeeper中共有9中操作：
create：创建一个znode
delete：删除一个znode
exists：测试一个znode
getACL，setACL：获取/设置一个znode的ACL（权限控制）
getChildren：获取一个znode的子节点
getData，setData：获取/设置一个znode所保存的数据
sync：将客户端的znode视图与ZooKeeper同步