Apache Curator入门实战
Curator是Netflix公司开源的一个Zookeeper客户端，与Zookeeper提供的原生客户端相比，Curator的抽象层次更高，简化了Zookeeper客户端的开发量。
1.Zookeeper安装部署
Zookeeper的部署很简单，如果已经有Java运行环境的话，下载tarball解压后即可运行。
[root-3.4.6/zookeeper-3.4.6.tar.gz[root@vm Temp]$ tar zxvf zookeeper-3.4.6.tar.gz[root@vm Temp]$ cd zookeeper-3.4.6[root@vm zookeeper-3.4.6]$ cp conf/zoo_sample.cfg conf/zoo.cfg[root@vm zookeeper-3.4.6]$ export ZOOKEEPER_HOME=/usr/local/src/zookeeper-3.4.5[root@vm zookeeper-3.4.6]$ export PATH=$ZOOKEEPER_HOME/bin:$PATH[root@vm zookeeper-3.4.6]$ bin/zkServer.sh start[root2.客户端常用操作
用zkCli.sh连接上Zookeeper服务后，用help能列出所有命令：
[root@BC-VM-edce4ac67d304079868c0bb265337bd4 zookeeper-3.4.6]# bin/zkCli.sh -127.0.0.1:2181Connecting to localhost:::09 GMT…[zk: localhost:2181(CONNECTED) 5] helpZooKeeper -server host:port cmd argsconnect host:portget path [watch]ls path [watch]set path data [version]rmr pathdelquota [-n|-b] pathquitprintwatches on|offcreate [-s] [-e] path data aclstat path [watch]closels2 path [watch]historylistquota pathsetAcl path aclgetAcl pathsync pathredo cmdnoaddauth scheme authdelete path [version]setquota -n|-b val path
下面就试验一下常用的命令：
[zk: localhost:2181(CONNECTED) 6] create /zktest mydataCreated /zktest[zk: localhost:2181(CONNECTED) 12] ls /[zktest, zookeeper][zk: localhost:2181(CONNECTED) 7] ls /zktest[][zk: localhost:2181(CONNECTED) 13] get /zktestmydatacZxid = 0x1cctime = Thu Jun 11 10:58:06 CST 2015mZxid = 0x1cmtime = Thu Jun 11 10:58:06 CST 2015pZxid = 0x1ccversion = 0dataVersion = 0aclVersion = 0ephemeralOwner = 0x0dataLength = 6numChildren = 0[zk: localhost:2181(CONNECTED) 14] set /zktest junkcZxid = 0x1cctime = Thu Jun 11 10:58:06 CST 2015mZxid = 0x1fmtime = Thu Jun 11 10:59:08 CST 2015pZxid = 0x1ccversion = 0dataVersion = 1aclVersion = 0ephemeralOwner = 0x0dataLength = 4numChildren = 0[zk: localhost:2181(CONNECTED) 15] delete /zktest[zk: localhost:2181(CONNECTED) 16] ls /[zookeeper]3.用Curator管理Zookeeper
Curator的Maven依赖如下，，一般直接使用curator-recipes就行了，如果需要自己封装一些底层些的功能的话，例如增加连接管理重试机制等，则可以引入curator-framework包。
>curator-recipes>3.1 Client操作
利用Curator提供的客户端API，可以完全实现上面原生客户端的功能。值得注意的是，Curator采用流式风格API。
package com.cdai.codebase.bigdata.hadoop.zookeeper.curator;import org.apache.curator.framework.CuratorFramework;import org.apache.curator.framework.CuratorFrameworkFactory;import org.apache.curator.retry.RetryNTimes;/** * Curator framework’s client test. * Output: * $ create /zktest hello * $ ls / * [zktest, zookeeper] * $ get /zktest * hello * $ set /zktest world * $ get /zktest * world * $ delete /zktest * $ ls / * [zookeeper] */{String ZK_ADDRESS = “192.168.1.100:2181”;String ZK_PATH = “/zktest”;(String[] args) throws Exception {// 1.Connect to zkCuratorFramework client = CuratorFrameworkFactory.newClient(ZK_ADDRESS,new RetryNTimes(10, 5000));client.start();System.out.println(“zk client start successfully!”);// 2.Client API test// 2.1 Create nodeString data1 = “hello”;print(“create”, ZK_PATH, data1);client.create().creatingParentsIfNeeded().forPath(ZK_PATH, data1.getBytes());// 2.2 Get node and dataprint(“ls”, “/”);print(client.getChildren().forPath(“/”));print(“get”, ZK_PATH);print(client.getData().forPath(ZK_PATH));// 2.3 Modify dataString data2 = “world”;print(“set”, ZK_PATH, data2);client.setData().forPath(ZK_PATH, data2.getBytes());print(“get”, ZK_PATH);print(client.getData().forPath(ZK_PATH));// 2.4 Remove nodeprint(“delete”, ZK_PATH);client.delete().forPath(ZK_PATH);print(“ls”, “/”);print(client.getChildren().forPath(“/”));}(String… cmds) {StringBuilder text = new StringBuilder(“$ “);for (String cmd : cmds) {text.append(cmd).append(” “);}System.out.println(text.toString());}(Object result) {System.out.println(result instanceof byte[]? new String((byte[]) result): result);}}3.2 监听器
Curator提供了三种Watcher(Cache)来监听结点的变化：
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