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客户端编程。
它包含以下几个组件:
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. |
示例:
<?xml version="1.0"?>
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<modelVersion>4.0.0</modelVersion>
<groupId>com.sf.zkclient</groupId>
<artifactId>zkclient</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>zkclient</name>
<url>http://maven.apache.org</url>
<properties>
<curator.version>2.11.1</curator.version>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</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>
</project>
java代码:
示例一:常见的添加、修改、删除示例:
public static void test() throws Exception {
String address = "localhost:2181";
CuratorFramework client = CuratorFrameworkFactory.newClient(address, new ExponentialBackoffRetry(1000, 3));
try{
client.start();
String path = "/yongjiu2/yongjiu3/test5";
//a. 创建永久性节点
client.create()
.creatingParentContainersIfNeeded()
.withMode(CreateMode.PERSISTENT)
.withACL(ZooDefs.Ids.OPEN_ACL_UNSAFE)
.forPath(path, "hello, zk".getBytes());
System.out.println("b");
//b. 创建临时节点
client.create().withMode(CreateMode.EPHEMERAL).forPath("/temptest5", "hello".getBytes());
System.out.println("c");
//c.获取节点值
byte[] buf = client.getData().forPath(path);
System.out.println("get data path:"+path+", data:"+new String(buf));
System.out.println("d");
//d.设置节点值
client.setData().inBackground().forPath(path, "ricky".getBytes());
System.out.println("e");
//e.checkExists
Stat stat = client.checkExists().forPath(path);
if(stat==null){
System.out.println("exec create path:"+path);
}else {
System.out.println("exec getData");
}
System.out.println("f");
//f.删除节点
client.delete().deletingChildrenIfNeeded().forPath(path);
byte[] buf2 = client.getData().forPath(path);
System.out.println("get data path:"+path+", data:"+new String(buf2));
}finally {
if(client!=null)
client.close();
}
}
示例二:临时节点不能有子节点、不能级联创建示例:
/**
* 级联创建临时节点测试,结果会创建不成功,报错
* @throws Exception
*/
public static void test2() throws Exception {
String address = "localhost:2181";
CuratorFramework client = CuratorFrameworkFactory.newClient(address, new ExponentialBackoffRetry(1000, 3));
try{
client.start();
String path = "/linshi";
//b. 创建临时节点
client.create().withMode(CreateMode.EPHEMERAL).forPath(path, "hello".getBytes());
byte[] buf = client.getData().forPath(path);
System.out.println("get data path:"+path+", data:"+new String(buf));
//Zookeeper创建临时节点的时候,不能创建级联的节点,下面的create会报错
String path2 = "/linshi/test";
//b. 创建临时节点
client.create().withMode(CreateMode.EPHEMERAL).forPath(path2, "hello".getBytes());
//byte[] buf2 = client.getData().forPath(path2);
//System.out.println("get data path:"+path2+", data:"+new String(buf2));
TimeUnit.SECONDS.sleep(100 * 1000);
}finally {
if(client!=null)
client.close();
}
}
示例三:3、临时节点何时失效演示(在会话结束时被移除)
/**
* 临时节点什么时候失效?是在本次会话结束时
* @throws Exception
*/
public static void test3() throws Exception {
String address = "localhost:2181";
CuratorFramework client = CuratorFrameworkFactory.newClient(address, new ExponentialBackoffRetry(1000, 3));
try{
client.start();
String path = "/linshi";
//b. 创建临时节点
client.create().withMode(CreateMode.EPHEMERAL).forPath(path, "hello".getBytes());
byte[] buf = client.getData().forPath(path);
System.out.println("get data path:"+path+", data:"+new String(buf));
TimeUnit.SECONDS.sleep(100 * 1000);
}finally {
if(client!=null)
client.close();
}
}