上篇文章主要讲述了Zookeeper的命令行操作，本文主要讲解Zookeeper的API代码应用，本文以代码为主，Zookeeper的部分相对来说都是比较简单的。关注专栏《破茧成蝶——Zookeeper篇》查看Zookeeper相关系列文章~
目录
一、添加pom.xml文件
在新建的Maven工程里面，添加如下依赖内容：
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>RELEASE</version>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-core</artifactId>
<version>2.8.2</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.apache.zookeeper/zookeeper -->
<dependency>
<groupId>org.apache.zookeeper</groupId>
<artifactId>zookeeper</artifactId>
<version>3.4.10</version>
</dependency>
</dependencies>二、查看Zookeeper中ZNode
/**
* 查看ZNode中包含的节点
* @throws KeeperException
* @throws InterruptedException
*/
@Test
public void ls() throws KeeperException, InterruptedException {
//默认回调函数
// List<String> children = zkCli.getChildren("/", true);
//自定义回调函数
List<String> children = zkCli.getChildren("/", e -> {
System.out.println("自定义回调函数");
});
System.out.println("=====================================");
for (String child: children) {
System.out.println(child);
}
System.out.println("=====================================");
Thread.sleep(Long.MAX_VALUE);
}三、创建节点
/**
* 创建节点
* @throws KeeperException
* @throws InterruptedException
*/
@Test
public void create() throws KeeperException, InterruptedException {
String s = zkCli.create("/test", "test".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
System.out.println(s);
Thread.sleep(Long.MAX_VALUE);
}四、获取节点信息
/**
* 获取节点信息
* @throws KeeperException
* @throws InterruptedException
*/
@Test
public void get() throws KeeperException, InterruptedException {
byte[] data = zkCli.getData("/xzw", true, new Stat());
String s = new String(data);
System.out.println(s);
}五、修改节点内容
/**
* 修改节点内容
* @throws KeeperException
* @throws InterruptedException
*/
@Test
public void set() throws KeeperException, InterruptedException {
Stat stat = zkCli.setData("/xzw", "test".getBytes(), 0);
System.out.println(stat.getDataLength());
}六、查看结构体
/**
* 查看结构体
* @throws KeeperException
* @throws InterruptedException
*/
@Test
public void stat() throws KeeperException, InterruptedException {
Stat exists = zkCli.exists("/xzw", false);
if (exists == null) {
System.out.println("节点不存在");
} else {
System.out.println(exists.getDataLength());
}
}七、删除节点
/**
* 删除节点
* @throws KeeperException
* @throws InterruptedException
*/
@Test
public void delete() throws KeeperException, InterruptedException {
Stat exists = zkCli.exists("/xzw", false);
if (exists != null)
zkCli.delete("/xzw", exists.getVersion());
}八、循环注册节点
/**
* 循环注册节点：当节点发生变化时，可以不停的通知
* @throws KeeperException
* @throws InterruptedException
*/
public void register() throws KeeperException, InterruptedException {
byte[] data = zkCli.getData("/xzw", new Watcher() {
@Override
public void process(WatchedEvent watchedEvent) {
try {
register();
} catch (KeeperException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}, null);
System.out.println(new String(data));
}
/**
* 测试循环注册
* @throws KeeperException
* @throws InterruptedException
*/
@Test
public void testRegister() throws KeeperException, InterruptedException {
register();
Thread.sleep(Long.MAX_VALUE);
}九、完整代码
package com.xzw.zookeeper;
import org.apache.zookeeper.*;
import org.apache.zookeeper.data.Stat;
import org.junit.Before;
import org.junit.Test;
import java.io.IOException;
import java.util.List;
/**
* @author: xzw
* @create_date: 2020/9/9 9:59
* @desc: Zookeeper客户端
* @modifier:
* @modified_date:
* @desc:
*/
public class ZkClient {
//定义Zookeeper客户端实例
private ZooKeeper zkCli;
//定义连接串
private static final String CONNECT_STRING = "master:2181,slave01:2181,slave02:2181";
//定义session timeout
private static final int SESSION_TIMEOUT = 2000;
/**
* 初始化Zookeeper，定义一个默认的回调函数
* @throws IOException
*/
@Before
public void before() throws IOException {
zkCli = new ZooKeeper(CONNECT_STRING, SESSION_TIMEOUT, e -> {
System.out.println("默认回调函数");
});
}
/**
* 查看ZNode中包含的节点
* @throws KeeperException
* @throws InterruptedException
*/
@Test
public void ls() throws KeeperException, InterruptedException {
//默认回调函数
// List<String> children = zkCli.getChildren("/", true);
//自定义回调函数
List<String> children = zkCli.getChildren("/", e -> {
System.out.println("自定义回调函数");
});
System.out.println("=====================================");
for (String child: children) {
System.out.println(child);
}
System.out.println("=====================================");
Thread.sleep(Long.MAX_VALUE);
}
/**
* 创建节点
* @throws KeeperException
* @throws InterruptedException
*/
@Test
public void create() throws KeeperException, InterruptedException {
String s = zkCli.create("/test", "test".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
System.out.println(s);
Thread.sleep(Long.MAX_VALUE);
}
/**
* 获取节点信息
* @throws KeeperException
* @throws InterruptedException
*/
@Test
public void get() throws KeeperException, InterruptedException {
byte[] data = zkCli.getData("/xzw", true, new Stat());
String s = new String(data);
System.out.println(s);
}
/**
* 修改节点内容
* @throws KeeperException
* @throws InterruptedException
*/
@Test
public void set() throws KeeperException, InterruptedException {
Stat stat = zkCli.setData("/xzw", "test".getBytes(), 0);
System.out.println(stat.getDataLength());
}
/**
* 查看结构体
* @throws KeeperException
* @throws InterruptedException
*/
@Test
public void stat() throws KeeperException, InterruptedException {
Stat exists = zkCli.exists("/xzw", false);
if (exists == null) {
System.out.println("节点不存在");
} else {
System.out.println(exists.getDataLength());
}
}
/**
* 删除节点
* @throws KeeperException
* @throws InterruptedException
*/
@Test
public void delete() throws KeeperException, InterruptedException {
Stat exists = zkCli.exists("/xzw", false);
if (exists != null)
zkCli.delete("/xzw", exists.getVersion());
}
/**
* 循环注册节点：当节点发生变化时，可以不停的通知
* @throws KeeperException
* @throws InterruptedException
*/
public void register() throws KeeperException, InterruptedException {
byte[] data = zkCli.getData("/xzw", new Watcher() {
@Override
public void process(WatchedEvent watchedEvent) {
try {
register();
} catch (KeeperException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}, null);
System.out.println(new String(data));
}
/**
* 测试循环注册
* @throws KeeperException
* @throws InterruptedException
*/
@Test
public void testRegister() throws KeeperException, InterruptedException {
register();
Thread.sleep(Long.MAX_VALUE);
}
}
至此，本文就结束了，你们在此过程中遇到了什么问题，欢迎留言，让我看看你们都遇到了哪些问题~