zookeeper api 操作znode

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/* * 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;/** *  * @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("process1 : " + event.getType());        }    };        private ZooKeeper zooKeeper;        /**     *  连接zookeeper     * <br>------------------------------<br>     * @throws IOException     */    @Before    public void connect() throws IOException {        zooKeeper  = new ZooKeeper("192.168.50.128:2181", SESSION_TIMEOUT, watcher);    }        /**     *  关闭连接     * <br>------------------------------<br>     */    @After    public 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>     */    @Test    public 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>     */    @Test    public void testDelete() {         try {            zooKeeper.delete("/zk001", -1);        } catch (Exception e) {             LOGGER.error(e.getMessage());             Assert.fail();        }    }        /**     *   获取数据     * <br>------------------------------<br>     */    @Test    public 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>     */    @Test    public 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>     */    @Test    public 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>     */    @Test    public 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>     */    @Test    public 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>     */    @Test    public void testExistsWatch2() {        Stat stat = null;         try {             stat = zooKeeper.exists("/zk002", new Watcher() {                @Override                public 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>     */    @Test    public 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();        }    }}

通过api进行zookeeper的创建节点和删除节点的操作，如果没有在创建后关闭zookeeper连接，那么该连接会在这个程序运行结束后还存在，所以创建的临时节点仍然存在，但是过一段时间以后，连接释放后，还会删除掉临时节点；如果创建临时节点后关闭了zookeeper，那么程序运行结束后，之前创建的临时节点会被删除；

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zooKeeper.getData("/zk001", new Watcher() {
public void process(WatchedEvent event) {
LOGGER.info("testGetDataWatch watch : {}", event.getType());
}
}, null);

当调用这个方法，传递watcher变量以后，当对这个znode再次调用setData 或者deleteData方法时，会调用watcher的回调函数process，进行相应的操作；

2）创建zookeeper

zooKeeper = new ZooKeeper("192.168.50.128:2181,192.168.50.129:2181", SESSION_TIMEOUT, watcher);

即使第一个参数只有一个host的ip，在zk集群都启动并运行正常时，调用zk的api新建节点，每个zk的server都会同步新建节点，无论zk的server是leader还是follower；

转载地址： http://blog.csdn.net/java2000_wl/article/details/8655146

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