Curator教程（一）快速入門

Curator是Netflix公司開源的一個Zookeeper用戶端，與Zookeeper提供的原生用戶端相比，Curator的抽象層次更高，簡化了Zookeeper用戶端編程。

它包含以下幾個組件：

Component	description
Recipes	Implementations of some of the common ZooKeeper “recipes”. The implementations are built on top of the Curator Framework.
Framework	The Curator Framework is a high-level API that greatly simplifies using ZooKeeper. It adds many features that build on ZooKeeper and handles the complexity of managing connections to the ZooKeeper cluster and retrying operations.
Utilities	Various utilities that are useful when using ZooKeeper.
Client	A replacement for the bundled ZooKeeper class that takes care of some low-level housekeeping and provides some useful utilities.
Errors	How Curator deals with errors, connection issues, recoverable exceptions, etc.
Extensions	The curator-recipes package implements the common recipes that are described in the ZooKeeper documentation. To avoid bloating that package, recipes/applications that have a vertical appeal will be put in separate “extension” packages using the naming convention curator-x-name.

環境配置 JDK 1.7 Zookeeper 3.4.8 Curator 2.11.1 Maven 3.3 快速入門 Maven依賴

<properties>    <java.version>1.7</java.version>    <curator.version>2.11.1</curator.version></properties><dependencies>    <dependency>        <groupId>org.apache.zookeeper</groupId>        <artifactId>zookeeper</artifactId>        <version>3.4.8</version>        <exclusions>            <exclusion>                <artifactId>slf4j-log4j12</artifactId>                <groupId>org.slf4j</groupId>            </exclusion>            <exclusion>                <artifactId>log4j</artifactId>                <groupId>log4j</groupId>            </exclusion>        </exclusions>    </dependency>    <dependency>        <groupId>org.apache.curator</groupId>        <artifactId>curator-framework</artifactId>        <version>${curator.version}</version>    </dependency>    <dependency>        <groupId>org.apache.curator</groupId>        <artifactId>curator-client</artifactId>        <version>${curator.version}</version>        <exclusions>            <exclusion>                <groupId>com.google.guava</groupId>                <artifactId>guava</artifactId>            </exclusion>        </exclusions>    </dependency>    <dependency>        <groupId>com.google.guava</groupId>        <artifactId>guava</artifactId>        <version>18.0</version>    </dependency></dependencies>

1.建立Curator 串連執行個體

String address = "localhost:2181";CuratorFramework client = CuratorFrameworkFactory.newClient(address, new ExponentialBackoffRetry(1000, 3));

注意：一個Zookeeper叢集只需要構造一個CuratorFramework 執行個體對象即可。

CuratorFramework 使用之前必須先調用

client.start();

完成一系列操作後，調用client.close();方法，可以使用try-finally語句：

CuratorFramework client = CuratorFrameworkFactory.newClient(address, new ExponentialBackoffRetry(1000, 3));try{    client.start();    ...}finally {    if(client!=null)        client.close();}

2.建立節點

a. 建立永久性節點

client.create()      .creatingParentContainersIfNeeded()      .withMode(CreateMode.PERSISTENT)      .withACL(ZooDefs.Ids.OPEN_ACL_UNSAFE)      .forPath(path, "hello, zk".getBytes());

b. 建立臨時節點

client.create().withMode(CreateMode.EPHEMERAL).forPath(path, "hello".getBytes());  

3.擷取節點值

byte[] buf = client.getData().forPath(path);System.out.println("get data path:"+path+", data:"+new String(buf));

4.設定節點值

client.setData().inBackground().forPath(path, "ricky".getBytes());

5.checkExists

Stat stat = client.checkExists().forPath(path);if(stat==null){    System.out.println("exec create path:"+path);}else {    System.out.println("exec getData");}

6.刪除節點

client.delete().deletingChildrenIfNeeded().forPath("/pandora");

點此下載完整代碼：https://github.com/TiFG/zookeeper-samples 參考

Getting Started：http://curator.apache.org/getting-started.html