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Zookeeper(5)JAVA API

2013-03-13 
Zookeeper(五)JAVA APIorg.apache.zookeeper.ZooKeeper类 主要方法列表方法名称描述String create(final S

Zookeeper(五)JAVA API

org.apache.zookeeper.ZooKeeper类 主要方法列表

方法名称描述String create(final String path, byte data[], List acl, CreateMode createMode)

创建一个znode节点,

参数: 路径、 znode内容,ACL(访问控制列表)、 znode创建类型

void delete(final String path, int version)

删除一个znode节点,

参数: 路径、版本号;如果版本号与znode的版本号不一致,将无法删除,是一种乐观加锁机制;如果将版本号设置为-1,不会去检测版本,直接删除;

Stat exists(final String path, Watcher watcher)

判断某个znode节点是否存在

参数: 路径、Watcher(监视器);当这个znode节点被改变时,将会触发当前Watcher

Stat exists(String path, boolean watch)

判断某个znode节点是否存在

参数: 路径、并设置是否监控这个目录节点,这里的 watcher 是在创建 ZooKeeper 实例时指定的 watcher

Stat setData(final String path, byte data[], int version)

设置某个znode上的数据

参数: 路径、数据、版本号;如果为-1,跳过版本检查

byte[] getData(final String path, Watcher watcher, Stat stat)

获取某个znode上的数据

参数: 路径、监视器、数据版本等信息

List getChildren(final String path, Watcher watcher)

获取某个节点下的所有子节点

参数: 路径、监视器;该方法有多个重载


znode创建类型(CreateMode):

PERSISTENT               持久化节点
   
PERSISTENT_SEQUENTIAL     顺序自动编号持久化节点,这种节点会根据当前已存在的节点数自动加 1
   
EPHEMERAL    临时节点, 客户端session超时这类节点就会被自动删除
  

EPHEMERAL_SEQUENTIAL   临时自动编号节点


/* * ZookeeperTest.java */package com.x.zookeeper;import java.io.IOException;import java.util.List;import org.apache.zookeeper.CreateMode;import org.apache.zookeeper.WatchedEvent;import org.apache.zookeeper.Watcher;import org.apache.zookeeper.ZooKeeper;import org.apache.zookeeper.ZooDefs.Ids;import org.apache.zookeeper.data.Stat;import org.junit.After;import org.junit.Assert;import org.junit.Before;import org.junit.Test;import org.slf4j.Logger;import org.slf4j.LoggerFactory;/** *  * @author http://blog.csdn.net/java2000_wl * @version <b>1.0</b> */public class ZookeeperTest {private static final int SESSION_TIMEOUT = 30000;public static final Logger LOGGER = LoggerFactory.getLogger(ZookeeperTest.class);private Watcher watcher =  new Watcher() {public void process(WatchedEvent event) {LOGGER.info("process : " + event.getType());}};private ZooKeeper zooKeeper;/** *  连接zookeeper * <br>------------------------------<br> * @throws IOException */@Beforepublic void connect() throws IOException {zooKeeper  = new ZooKeeper("localhost:2181,localhost:2182,localhost:2183", SESSION_TIMEOUT, watcher);}/** *  关闭连接 * <br>------------------------------<br> */@Afterpublic void close() {try {zooKeeper.close();} catch (InterruptedException e) {e.printStackTrace();}}/** * 创建一个znode  *  1.CreateMode 取值   *  PERSISTENT:持久化,这个目录节点存储的数据不会丢失 *  PERSISTENT_SEQUENTIAL:顺序自动编号的目录节点,这种目录节点会根据当前已近存在的节点数自动加 1,然后返回给客户端已经成功创建的目录节点名; *  EPHEMERAL:临时目录节点,一旦创建这个节点的客户端与服务器端口也就是 session过期超时,这种节点会被自动删除 *  EPHEMERAL_SEQUENTIAL:临时自动编号节点 * <br>------------------------------<br> */@Testpublic void testCreate() {String result = null; try { result = zooKeeper.create("/zk001", "zk001data".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);} catch (Exception e) { LOGGER.error(e.getMessage()); Assert.fail();} LOGGER.info("create result : {}", result); }/** * 删除节点  忽略版本 * <br>------------------------------<br> */@Testpublic void testDelete() { try {zooKeeper.delete("/zk001", -1);} catch (Exception e) { LOGGER.error(e.getMessage()); Assert.fail();}}/** *   获取数据 * <br>------------------------------<br> */@Testpublic void testGetData() {String result = null; try { byte[] bytes = zooKeeper.getData("/zk001", null, null); result = new String(bytes);} catch (Exception e) { LOGGER.error(e.getMessage()); Assert.fail();} LOGGER.info("getdata result : {}", result);}/** *   获取数据  设置watch * <br>------------------------------<br> */@Testpublic void testGetDataWatch() {String result = null; try { byte[] bytes = zooKeeper.getData("/zk001", new Watcher() {public void process(WatchedEvent event) {LOGGER.info("testGetDataWatch  watch : {}", event.getType());} }, null); result = new String(bytes);} catch (Exception e) { LOGGER.error(e.getMessage()); Assert.fail();} LOGGER.info("getdata result : {}", result);  // 触发wacth  NodeDataChanged try { zooKeeper.setData("/zk001", "testSetData".getBytes(), -1);} catch (Exception e) { LOGGER.error(e.getMessage()); Assert.fail();}}/** *    判断节点是否存在 *    设置是否监控这个目录节点,这里的 watcher 是在创建 ZooKeeper实例时指定的 watcher * <br>------------------------------<br> */@Testpublic void testExists() {Stat stat = null; try { stat = zooKeeper.exists("/zk001", false);} catch (Exception e) { LOGGER.error(e.getMessage()); Assert.fail();} Assert.assertNotNull(stat); LOGGER.info("exists result : {}", stat.getCzxid());}/** *     设置对应znode下的数据  ,  -1表示匹配所有版本 * <br>------------------------------<br> */@Testpublic void testSetData() {Stat stat = null; try { stat = zooKeeper.setData("/zk001", "testSetData".getBytes(), -1);} catch (Exception e) { LOGGER.error(e.getMessage()); Assert.fail();} Assert.assertNotNull(stat); LOGGER.info("exists result : {}", stat.getVersion());}/** *    判断节点是否存在,  *    设置是否监控这个目录节点,这里的 watcher 是在创建 ZooKeeper实例时指定的 watcher * <br>------------------------------<br> */@Testpublic void testExistsWatch1() {Stat stat = null; try { stat = zooKeeper.exists("/zk001", true);} catch (Exception e) { LOGGER.error(e.getMessage()); Assert.fail();} Assert.assertNotNull(stat);  try {zooKeeper.delete("/zk001", -1);} catch (Exception e) {e.printStackTrace();}}/** *    判断节点是否存在,  *    设置监控这个目录节点的 Watcher * <br>------------------------------<br> */@Testpublic void testExistsWatch2() {Stat stat = null; try { stat = zooKeeper.exists("/zk002", new Watcher() {@Overridepublic void process(WatchedEvent event) {LOGGER.info("testExistsWatch2  watch : {}", event.getType());} });} catch (Exception e) { LOGGER.error(e.getMessage()); Assert.fail();} Assert.assertNotNull(stat);  // 触发watch 中的process方法   NodeDataChanged try {zooKeeper.setData("/zk002", "testExistsWatch2".getBytes(), -1);} catch (Exception e) {e.printStackTrace();}  // 不会触发watch 只会触发一次 try {zooKeeper.delete("/zk002", -1);} catch (Exception e) {e.printStackTrace();}}/** *  获取指定节点下的子节点 * <br>------------------------------<br> */@Testpublic void testGetChild() { try { zooKeeper.create("/zk/001", "001".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT); zooKeeper.create("/zk/002", "002".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);  List<String> list = zooKeeper.getChildren("/zk", true);for (String node : list) {LOGGER.info("node {}", node);}} catch (Exception e) { LOGGER.error(e.getMessage()); Assert.fail();}}}


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