Apache Curator入门实战

版权声明：本文为博主原创文章，未经博主允许不得转载。

目录(?)[-]

1. Apache Curator入门实战
2. Zookeeper安装部署
3. 客户端常用操作
4. 用Curator管理Zookeeper
   1. 1 Client操作
   2. 2 监听器
5. Curator菜谱
   1. 1 分布式锁
   2. 2 Leader选举

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。

<code class="hljs ruby has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">[root<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@vm</span> <span class="hljs-constant" style="box-sizing: border-box;">Temp</span>]<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">$ </span>wget <span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">http:</span>/<span class="hljs-regexp" style="color: rgb(0, 136, 0); box-sizing: border-box;">/mirror.bit.edu.cn/apache</span><span class="hljs-regexp" style="color: rgb(0, 136, 0); box-sizing: border-box;">/zookeeper/zookeeper</span>-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3.4</span>.<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">6</span>/zookeeper-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3.4</span>.<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">6</span>.tar.gz
[root<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@vm</span> <span class="hljs-constant" style="box-sizing: border-box;">Temp</span>]<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">$ </span>tar zxvf zookeeper-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3.4</span>.<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">6</span>.tar.gz
[root<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@vm</span> <span class="hljs-constant" style="box-sizing: border-box;">Temp</span>]<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">$ </span>cd zookeeper-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3.4</span>.<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">6</span>

[root<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@vm</span> zookeeper-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3.4</span>.<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">6</span>]<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">$ </span>cp conf/zoo_sample.cfg conf/zoo.cfg
[root<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@vm</span> zookeeper-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3.4</span>.<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">6</span>]<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">$ </span>export <span class="hljs-constant" style="box-sizing: border-box;">ZOOKEEPER_HOME</span>=<span class="hljs-regexp" style="color: rgb(0, 136, 0); box-sizing: border-box;">/usr/local</span><span class="hljs-regexp" style="color: rgb(0, 136, 0); box-sizing: border-box;">/src/zookeeper</span>-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3.4</span>.<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span>
[root<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@vm</span> zookeeper-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3.4</span>.<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">6</span>]<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">$ </span>export <span class="hljs-constant" style="box-sizing: border-box;">PATH</span>=<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">$ZOOKEEPER_HOME</span>/<span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">bin:</span><span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">$PATH</span>

[root<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@vm</span> zookeeper-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3.4</span>.<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">6</span>]<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">$ </span>bin/zkServer.sh start
[root<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@vm</span> zookeeper-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3.4</span>.<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">6</span>]<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">$ </span>bin/zkCli.sh -server <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">127.0</span>.<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>.<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span><span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">:</span><span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2181</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li></ul>

2.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：

<code class="hljs r has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">[root@BC-VM-edce4ac67d304079868c0bb265337bd4 zookeeper-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3.4</span><span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">.6</span>]<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># bin/zkCli.sh -127.0.0.1:2181</span>
Connecting to localhost:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2181</span>
<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2015</span>-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">06</span>-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">11</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">55</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">14</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">387</span> [myid:] - INFO  [main:Environment@<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">100</span>] - Client environment:zookeeper.version=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3.4</span><span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">.6</span>-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1569965</span>, built on <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">02</span>/<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">20</span>/<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2014</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">09</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">09</span> GMT
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>

[zk: localhost:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2181</span>(CONNECTED) <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span>] help
ZooKeeper -server host:port cmd args
        connect host:port
        get path [watch]
        ls path [watch]
        set path data [version]
        rmr path
        delquota [-n|-b] path
        quit 
        printwatches on|off
        create [-s] [-e] path data acl
        stat path [watch]
        close 
        ls2 path [watch]
        history 
        listquota path
        setAcl path acl
        getAcl path
        sync path
        redo cmdno
        addauth scheme auth
        delete path [version]
        setquota -n|-b val path</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li></ul>

下面就试验一下常用的命令：

• create：创建路径结点。
• ls：查看路径下的所有结点。
• get：获得结点上的值。
• set：修改结点上的值。
• delete：删除结点。

<code class="hljs makefile has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">[zk: localhost:2181(CONNECTED) 6] create /zktest mydata
Created /zktest
[zk: localhost:2181(CONNECTED) 12] ls /
[zktest, zookeeper]
[zk: localhost:2181(CONNECTED) 7] ls /zktest
[]
[zk: localhost:2181(CONNECTED) 13] get /zktest
mydata
<span class="hljs-constant" style="box-sizing: border-box;">cZxid</span> = 0x1c
<span class="hljs-constant" style="box-sizing: border-box;">ctime</span> = Thu Jun 11 10:58:06 CST 2015
<span class="hljs-constant" style="box-sizing: border-box;">mZxid</span> = 0x1c
<span class="hljs-constant" style="box-sizing: border-box;">mtime</span> = Thu Jun 11 10:58:06 CST 2015
<span class="hljs-constant" style="box-sizing: border-box;">pZxid</span> = 0x1c
<span class="hljs-constant" style="box-sizing: border-box;">cversion</span> = 0
<span class="hljs-constant" style="box-sizing: border-box;">dataVersion</span> = 0
<span class="hljs-constant" style="box-sizing: border-box;">aclVersion</span> = 0
<span class="hljs-constant" style="box-sizing: border-box;">ephemeralOwner</span> = 0x0
<span class="hljs-constant" style="box-sizing: border-box;">dataLength</span> = 6
<span class="hljs-constant" style="box-sizing: border-box;">numChildren</span> = 0
[zk: localhost:2181(CONNECTED) 14] set /zktest junk
<span class="hljs-constant" style="box-sizing: border-box;">cZxid</span> = 0x1c
<span class="hljs-constant" style="box-sizing: border-box;">ctime</span> = Thu Jun 11 10:58:06 CST 2015
<span class="hljs-constant" style="box-sizing: border-box;">mZxid</span> = 0x1f
<span class="hljs-constant" style="box-sizing: border-box;">mtime</span> = Thu Jun 11 10:59:08 CST 2015
<span class="hljs-constant" style="box-sizing: border-box;">pZxid</span> = 0x1c
<span class="hljs-constant" style="box-sizing: border-box;">cversion</span> = 0
<span class="hljs-constant" style="box-sizing: border-box;">dataVersion</span> = 1
<span class="hljs-constant" style="box-sizing: border-box;">aclVersion</span> = 0
<span class="hljs-constant" style="box-sizing: border-box;">ephemeralOwner</span> = 0x0
<span class="hljs-constant" style="box-sizing: border-box;">dataLength</span> = 4
<span class="hljs-constant" style="box-sizing: border-box;">numChildren</span> = 0
[zk: localhost:2181(CONNECTED) 15] delete /zktest
[zk: localhost:2181(CONNECTED) 16] ls /
[zookeeper]</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li></ul>

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。

<code class="language-xml hljs  has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">    <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">dependency</span>></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">groupId</span>></span>org.apache.curator<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">groupId</span>></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">artifactId</span>></span>curator-recipes<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">artifactId</span>></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">version</span>></span>2.7.0<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">version</span>></span>
    <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">dependency</span>></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li></ul>

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。

<code class="language-java hljs  has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">package</span> com.cdai.codebase.bigdata.hadoop.zookeeper.curator;

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> org.apache.curator.framework.CuratorFramework;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> org.apache.curator.framework.CuratorFrameworkFactory;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> org.apache.curator.retry.RetryNTimes;

<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
 * 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]
 */</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">CuratorClientTest</span> {</span>

    <span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/** Zookeeper info */</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> String ZK_ADDRESS = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"192.168.1.100:2181"</span>;
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> String ZK_PATH = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/zktest"</span>;

    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">main</span>(String[] args) <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">throws</span> Exception {
        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 1.Connect to zk</span>
        CuratorFramework client = CuratorFrameworkFactory.newClient(
                ZK_ADDRESS,
                <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> RetryNTimes(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5000</span>)
        );
        client.start();
        System.out.println(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"zk client start successfully!"</span>);

        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 2.Client API test</span>
        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 2.1 Create node</span>
        String data1 = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"hello"</span>;
        print(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"create"</span>, ZK_PATH, data1);
        client.create().
                creatingParentsIfNeeded().
                forPath(ZK_PATH, data1.getBytes());

        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 2.2 Get node and data</span>
        print(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"ls"</span>, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/"</span>);
        print(client.getChildren().forPath(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/"</span>));
        print(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"get"</span>, ZK_PATH);
        print(client.getData().forPath(ZK_PATH));

        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 2.3 Modify data</span>
        String data2 = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"world"</span>;
        print(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"set"</span>, ZK_PATH, data2);
        client.setData().forPath(ZK_PATH, data2.getBytes());
        print(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"get"</span>, ZK_PATH);
        print(client.getData().forPath(ZK_PATH));

        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 2.4 Remove node</span>
        print(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"delete"</span>, ZK_PATH);
        client.delete().forPath(ZK_PATH);
        print(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"ls"</span>, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/"</span>);
        print(client.getChildren().forPath(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/"</span>));
    }

    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">print</span>(String... cmds) {
        StringBuilder text = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> StringBuilder(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"$ "</span>);
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (String cmd : cmds) {
            text.append(cmd).append(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">" "</span>);
        }
        System.out.println(text.toString());
    }

    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">print</span>(Object result) {
        System.out.println(
                result <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">instanceof</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">byte</span>[]
                    ? <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> String((<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">byte</span>[]) result)
                        : result);
    }

}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li><li style="box-sizing: border-box; padding: 0px 5px;">54</li><li style="box-sizing: border-box; padding: 0px 5px;">55</li><li style="box-sizing: border-box; padding: 0px 5px;">56</li><li style="box-sizing: border-box; padding: 0px 5px;">57</li><li style="box-sizing: border-box; padding: 0px 5px;">58</li><li style="box-sizing: border-box; padding: 0px 5px;">59</li><li style="box-sizing: border-box; padding: 0px 5px;">60</li><li style="box-sizing: border-box; padding: 0px 5px;">61</li><li style="box-sizing: border-box; padding: 0px 5px;">62</li><li style="box-sizing: border-box; padding: 0px 5px;">63</li><li style="box-sizing: border-box; padding: 0px 5px;">64</li><li style="box-sizing: border-box; padding: 0px 5px;">65</li><li style="box-sizing: border-box; padding: 0px 5px;">66</li><li style="box-sizing: border-box; padding: 0px 5px;">67</li><li style="box-sizing: border-box; padding: 0px 5px;">68</li><li style="box-sizing: border-box; padding: 0px 5px;">69</li><li style="box-sizing: border-box; padding: 0px 5px;">70</li><li style="box-sizing: border-box; padding: 0px 5px;">71</li><li style="box-sizing: border-box; padding: 0px 5px;">72</li><li style="box-sizing: border-box; padding: 0px 5px;">73</li><li style="box-sizing: border-box; padding: 0px 5px;">74</li><li style="box-sizing: border-box; padding: 0px 5px;">75</li><li style="box-sizing: border-box; padding: 0px 5px;">76</li><li style="box-sizing: border-box; padding: 0px 5px;">77</li><li style="box-sizing: border-box; padding: 0px 5px;">78</li><li style="box-sizing: border-box; padding: 0px 5px;">79</li><li style="box-sizing: border-box; padding: 0px 5px;">80</li></ul>

3.2 监听器

Curator提供了三种Watcher(Cache)来监听结点的变化：

• Path Cache：监视一个路径下1）孩子结点的创建、2）删除，3）以及结点数据的更新。产生的事件会传递给注册的PathChildrenCacheListener。
• Node Cache：监视一个结点的创建、更新、删除，并将结点的数据缓存在本地。
• Tree Cache：Path Cache和Node Cache的“合体”，监视路径下的创建、更新、删除事件，并缓存路径下所有孩子结点的数据。

下面就测试一下最简单的Path Watcher：

<code class="language-java hljs  has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">package</span> com.cdai.codebase.bigdata.hadoop.zookeeper.curator;

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> org.apache.curator.framework.CuratorFramework;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> org.apache.curator.framework.CuratorFrameworkFactory;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> org.apache.curator.framework.recipes.cache.ChildData;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> org.apache.curator.framework.recipes.cache.PathChildrenCache;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> org.apache.curator.framework.recipes.cache.PathChildrenCache.StartMode;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> org.apache.curator.retry.RetryNTimes;

<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
 * Curator framework watch test.
 */</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">CuratorWatcherTest</span> {</span>

    <span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/** Zookeeper info */</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> String ZK_ADDRESS = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"192.168.1.100:2181"</span>;
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> String ZK_PATH = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/zktest"</span>;

    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">main</span>(String[] args) <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">throws</span> Exception {
        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 1.Connect to zk</span>
        CuratorFramework client = CuratorFrameworkFactory.newClient(
                ZK_ADDRESS,
                <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> RetryNTimes(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5000</span>)
        );
        client.start();
        System.out.println(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"zk client start successfully!"</span>);

        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 2.Register watcher</span>
        PathChildrenCache watcher = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> PathChildrenCache(
                client,
                ZK_PATH,
                <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// if cache data</span>
        );
        watcher.getListenable().addListener((client1, event) -> {
            ChildData data = event.getData();
            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (data == <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>) {
                System.out.println(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"No data in event["</span> + event + <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"]"</span>);
            } <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> {
                System.out.println(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Receive event: "</span>
                        + <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"type=["</span> + event.getType() + <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"]"</span>
                        + <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">", path=["</span> + data.getPath() + <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"]"</span>
                        + <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">", data=["</span> + <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> String(data.getData()) + <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"]"</span>
                        + <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">", stat=["</span> + data.getStat() + <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"]"</span>);
            }
        });
        watcher.start(StartMode.BUILD_INITIAL_CACHE);
        System.out.println(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Register zk watcher successfully!"</span>);

        Thread.sleep(Integer.MAX_VALUE);
    }

}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li></ul>

下面是在zkCli.sh中操作时Java程序的输出：

<code class="hljs http has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-attribute" style="box-sizing: border-box;">Java</span>: <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">zk client start successfully!</span>
<span class="hljs-attribute" style="box-sizing: border-box;">Java</span>: <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">Register zk watcher successfully!</span>

<span class="http" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">zkCli</span>: <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">[zk: localhost:2181(CONNECTED) 11] create /zktest/hello mydata</span>
<span class="hljs-attribute" style="box-sizing: border-box;">Java</span>: <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">Receive event: type=[CHILD_ADDED], path=[/zktest/hello], data=[mydata], stat=[121,121,1434001221097,1434001221097,0,0,0,0,6,0,121]</span>

<span class="http" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">zkCli</span>: <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">[zk: localhost:2181(CONNECTED) 12] set /zktest/hello otherdata</span>
<span class="hljs-attribute" style="box-sizing: border-box;">Java</span>: <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">Receive event: type=[CHILD_UPDATED], path=[/zktest/hello], data=[otherdata], stat=[121,122,1434001221097,1434001228467,1,0,0,0,9,0,121]</span>

<span class="http" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">zkCli</span>: <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">[zk: localhost:2181(CONNECTED) 13] delete /zktest/hello</span>
<span class="hljs-attribute" style="box-sizing: border-box;">Java</span>: <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">Receive event: type=[CHILD_REMOVED], path=[/zktest/hello], data=[otherdata], stat=[121,122,1434001221097,1434001228467,1,0,0,0,9,0,121]</span></span></span></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li></ul>

4.Curator“菜谱”

既然Maven包叫做curator-recipes，那说明Curator有它独特的“菜谱”：

• 锁：包括共享锁、共享可重入锁、读写锁等。
• 选举：Leader选举算法。
• Barrier：阻止分布式计算直至某个条件被满足的“栅栏”，可以看做JDK Concurrent包中Barrier的分布式实现。
• 缓存：前面提到过的三种Cache及监听机制。
• 持久化结点：连接或Session终止后仍然在Zookeeper中存在的结点。
• 队列：分布式队列、分布式优先级队列等。

4.1 分布式锁

分布式编程时，比如最容易碰到的情况就是应用程序在线上多机部署，于是当多个应用同时访问某一资源时，就需要某种机制去协调它们。例如，现在一台应用正在rebuild缓存内容，要临时锁住某个区域暂时不让访问；又比如调度程序每次只想一个任务被一台应用执行等等。

下面的程序会启动两个线程t1和t2去争夺锁，拿到锁的线程会占用5秒。运行多次可以观察到，有时是t1先拿到锁而t2等待，有时又会反过来。Curator会用我们提供的lock路径的结点作为全局锁，这个结点的数据类似这种格式：[_c_64e0811f-9475-44ca-aa36-c1db65ae5350-lock-0000000005]，每次获得锁时会生成这种串，释放锁时清空数据。

<code class="language-java hljs  has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">package</span> com.cdai.codebase.bigdata.hadoop.zookeeper.curator;

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> org.apache.curator.framework.CuratorFramework;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> org.apache.curator.framework.CuratorFrameworkFactory;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> org.apache.curator.framework.recipes.locks.InterProcessMutex;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> org.apache.curator.retry.RetryNTimes;

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> java.util.concurrent.TimeUnit;

<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
 * Curator framework's distributed lock test.
 */</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">CuratorDistrLockTest</span> {</span>

    <span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/** Zookeeper info */</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> String ZK_ADDRESS = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"192.168.1.100:2181"</span>;
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> String ZK_LOCK_PATH = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/zktest"</span>;

    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">main</span>(String[] args) <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">throws</span> InterruptedException {
        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 1.Connect to zk</span>
        CuratorFramework client = CuratorFrameworkFactory.newClient(
                ZK_ADDRESS,
                <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> RetryNTimes(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5000</span>)
        );
        client.start();
        System.out.println(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"zk client start successfully!"</span>);

        Thread t1 = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Thread(() -> {
            doWithLock(client);
        }, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"t1"</span>);
        Thread t2 = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Thread(() -> {
            doWithLock(client);
        }, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"t2"</span>);

        t1.start();
        t2.start();
    }

    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">doWithLock</span>(CuratorFramework client) {
        InterProcessMutex lock = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> InterProcessMutex(client, ZK_LOCK_PATH);
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">try</span> {
            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (lock.acquire(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span> * <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1000</span>, TimeUnit.SECONDS)) {
                System.out.println(Thread.currentThread().getName() + <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">" hold lock"</span>);
                Thread.sleep(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5000</span>L);
                System.out.println(Thread.currentThread().getName() + <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">" release lock"</span>);
            }
        } <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (Exception e) {
            e.printStackTrace();
        } <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">finally</span> {
            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">try</span> {
                lock.release();
            } <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (Exception e) {
                e.printStackTrace();
            }
        }

    }

}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li><li style="box-sizing: border-box; padding: 0px 5px;">54</li><li style="box-sizing: border-box; padding: 0px 5px;">55</li><li style="box-sizing: border-box; padding: 0px 5px;">56</li><li style="box-sizing: border-box; padding: 0px 5px;">57</li><li style="box-sizing: border-box; padding: 0px 5px;">58</li><li style="box-sizing: border-box; padding: 0px 5px;">59</li></ul>

4.2 Leader选举

当集群里的某个服务down机时，我们可能要从slave结点里选出一个作为新的master，这时就需要一套能在分布式环境中自动协调的Leader选举方法。Curator提供了LeaderSelector监听器实现Leader选举功能。同一时刻，只有一个Listener会进入takeLeadership()方法，说明它是当前的Leader。注意：当Listener从takeLeadership()退出时就说明它放弃了“Leader身份”，这时Curator会利用Zookeeper再从剩余的Listener中选出一个新的Leader。autoRequeue()方法使放弃Leadership的Listener有机会重新获得Leadership，如果不设置的话放弃了的Listener是不会再变成Leader的。

<code class="language-java hljs  has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">package</span> com.cdai.codebase.bigdata.hadoop.zookeeper.curator;

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> org.apache.curator.framework.CuratorFramework;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> org.apache.curator.framework.CuratorFrameworkFactory;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> org.apache.curator.framework.recipes.leader.LeaderSelector;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> org.apache.curator.framework.recipes.leader.LeaderSelectorListener;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> org.apache.curator.framework.state.ConnectionState;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> org.apache.curator.retry.RetryNTimes;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> org.apache.curator.utils.EnsurePath;

<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
 * Curator framework's leader election test.
 * Output:
 *  LeaderSelector-2 take leadership!
 *  LeaderSelector-2 relinquish leadership!
 *  LeaderSelector-1 take leadership!
 *  LeaderSelector-1 relinquish leadership!
 *  LeaderSelector-0 take leadership!
 *  LeaderSelector-0 relinquish leadership! 
 *      ...
 */</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">CuratorLeaderTest</span> {</span>

    <span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/** Zookeeper info */</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> String ZK_ADDRESS = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"192.168.1.100:2181"</span>;
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> String ZK_PATH = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/zktest"</span>;

    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">main</span>(String[] args) <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">throws</span> InterruptedException {
        LeaderSelectorListener listener = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> LeaderSelectorListener() {
            <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">takeLeadership</span>(CuratorFramework client) <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">throws</span> Exception {
                System.out.println(Thread.currentThread().getName() + <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">" take leadership!"</span>);

                <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// takeLeadership() method should only return when leadership is being relinquished.</span>
                Thread.sleep(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5000</span>L);

                System.out.println(Thread.currentThread().getName() + <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">" relinquish leadership!"</span>);
            }

            <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">stateChanged</span>(CuratorFramework client, ConnectionState state) {
            }
        };

        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Thread(() -> {
            registerListener(listener);
        }).start();

        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Thread(() -> {
            registerListener(listener);
        }).start();

        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Thread(() -> {
            registerListener(listener);
        }).start();

        Thread.sleep(Integer.MAX_VALUE);
    }

    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">registerListener</span>(LeaderSelectorListener listener) {
        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 1.Connect to zk</span>
        CuratorFramework client = CuratorFrameworkFactory.newClient(
                ZK_ADDRESS,
                <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> RetryNTimes(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5000</span>)
        );
        client.start();

        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 2.Ensure path</span>
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">try</span> {
            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> EnsurePath(ZK_PATH).ensure(client.getZookeeperClient());
        } <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (Exception e) {
            e.printStackTrace();
        }

        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 3.Register listener</span>
        LeaderSelector selector = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> LeaderSelector(client, ZK_PATH, listener);
        selector.autoRequeue();
        selector.start();
    }

}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li><li style="box-sizing: border-box; padding: 0px 5px;">54</li><li style="box-sizing: border-box; padding: 0px 5px;">55</li><li style="box-sizing: border-box; padding: 0px 5px;">56</li><li style="box-sizing: border-box; padding: 0px 5px;">57</li><li style="box-sizing: border-box; padding: 0px 5px;">58</li><li style="box-sizing: border-box; padding: 0px 5px;">59</li><li style="box-sizing: border-box; padding: 0px 5px;">60</li><li style="box-sizing: border-box; padding: 0px 5px;">61</li><li style="box-sizing: border-box; padding: 0px 5px;">62</li><li style="box-sizing: border-box; padding: 0px 5px;">63</li><li style="box-sizing: border-box; padding: 0px 5px;">64</li><li style="box-sizing: border-box; padding: 0px 5px;">65</li><li style="box-sizing: border-box; padding: 0px 5px;">66</li><li style="box-sizing: border-box; padding: 0px 5px;">67</li><li style="box-sizing: border-box; padding: 0px 5px;">68</li><li style="box-sizing: border-box; padding: 0px 5px;">69</li><li style="box-sizing: border-box; padding: 0px 5px;">70</li><li style="box-sizing: border-box; padding: 0px 5px;">71</li><li style="box-sizing: border-box; padding: 0px 5px;">72</li><li style="box-sizing: border-box; padding: 0px 5px;">73</li><li style="box-sizing: border-box; padding: 0px 5px;">74</li><li style="box-sizing: border-box; padding: 0px 5px;">75</li><li style="box-sizing: border-box; padding: 0px 5px;">76</li><li style="box-sizing: border-box; padding: 0px 5px;">77</li><li style="box-sizing: border-box; padding: 0px 5px;">78</li><li style="box-sizing: border-box; padding: 0px 5px;">79</li><li style="box-sizing: border-box; padding: 0px 5px;">80</li><li style="box-sizing: border-box; padding: 0px 5px;">81</li></ul>

转载地址:http://blog.csdn.net/dc_726/article/details/46475633