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文章目录
2.1.在pom.xml文件中增加zookeeper依赖(记得跟自己的zookeeper版本对应)
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不懂如何搭建zookeeper集群的小伙伴可以移步到我的另一篇文章喔,里面有详细的zookeeper集群搭建教程~
zookeeper集群搭建步骤(超详细)
https://blog.csdn.net/weixin_47025166/article/details/125415538?spm=1001.2014.3001.5502
除此之外,我们也引入junit和log4j方便我们后面的测试
- <!--引入对应的zookeeper -->
- <dependency>
- <groupId>org.apache.zookeeper</groupId>
- <artifactId>zookeeper</artifactId>
- <version>3.7.1</version>
- </dependency>
-
- <!--引入日志-->
- <dependency>
- <groupId>org.apache.logging.log4j</groupId>
- <artifactId>log4j-to-slf4j</artifactId>
- <version>2.17.2</version>
- </dependency>
-
- <!--引入junit测试-->
- <dependency>
- <groupId>junit</groupId>
- <artifactId>junit</artifactId>
- <version>RELEASE</version>
- </dependency>

我们创建zkClient类用于实现对zookeeper中节点的操作:
1.客户端初始化
- package com.canrioyuan.zookeepertest;
-
- 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;
-
- //创建对应的zookeeper客户端
- public class ZkClient {
-
- //对应的zookeeper客户端连接,连接之间不能存在空格
- private String connectString = "192.168.154.133:2181,192.168.154.134:2181,192.168.154.135:2181";
- //即超时时间,我们设置成2s
- private int sessionTimeout = 2000;
- //声明zookeeper客户端
- private ZooKeeper zkClient;
-
-
- //初始化
- @Test
- public void init() throws IOException {
- zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
- @Override
- public void process(WatchedEvent watchedEvent) {
-
- }
- });
- }
-
- }

运行测试,成功后如会出现下图所示结果:

2.创建节点
- //创建节点
- @Test
- public void create() throws InterruptedException, KeeperException {
- //public String create(String path, byte[] data, List<ACL> acl, CreateMode createMode)
- //上图中从左到右的参数分别对应着:你所要创建的节点的名字,节点的值,节点的权限,节点的类型(持久有序,持久无序,临时有序,临时无序)
- zkClient.create("/class", "LiHua".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
- }
运行测试,你会发现,程序报了这样的错误;

这是因为我们测试方法是互相独立的,此时运行测试,客户端处于未初始化的状态。因此,我们在客户端类的init方法中将@Test注解改成@Before注解,表示在每个测试执行之前都必须执行初始化方法。
- //初始化
- @Before
- // @Test
- public void init() throws IOException {
- zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
- @Override
- public void process(WatchedEvent watchedEvent) {
-
- }
- });
- }
这时候我们再运行,会提示运行成功

我们来到任意一台zookeeper客户端中查看节点,会发现已经创建成功

3.监听节点的状态
一次监听只能生效一次,而为了能够持续监听,我们对初始化方法再做出调整,保证每次初始化都有一次监听生效。
- @Before
- public void init() throws IOException {
- zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
- @Override //process中即为监听后做出的处理
- public void process(WatchedEvent watchedEvent) {
- List<String> children = null;
- try {
- children = zkClient.getChildren("/", true);
- } catch (KeeperException e) {
- e.printStackTrace();
- } catch (InterruptedException e) {
- e.printStackTrace();
- }
- System.out.println("-------------------------");
- for (String child : children) {
- System.out.println(child);
- }
- System.out.println("-------------------------");
-
- }
- });
- }

然后在监听节点代码中进行延时操作
- //监听节点
- @Test
- public void getChildren() throws InterruptedException, KeeperException {
-
- //正常一次监听只会生效一次,因此我们设置延时监听,确保能够持续监听节点的变化。
- Thread.sleep(Long.MAX_VALUE);
- }
此时我们可以看到控制台输出了zookeeper中的节点:

我们进入zookeeper客户端对节点进行操作
增加一个节点school

返回控制台,此时已经监听到了节点的变化:

我们再对school这个节点进行删除操作

此时控制台同样监听到了节点的变化:

4.判断节点是否存在
- //判断节点是否存在
- @Test
- public void status() throws InterruptedException, KeeperException {
- Stat status = zkClient.exists("/class", false);
- System.out.println(status == null ? "no exist" : "exist");
- }
此时zookeeper中的节点;
![]()
测试结果:
![]()
- package com.canrioyuan.zookeepertest;
-
- 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;
-
- //创建对应的zookeeper客户端
- public class ZkClient {
-
- //对应的zookeeper客户端连接,连接之间不能存在空格
- private String connectString = "192.168.154.133:2181,192.168.154.134:2181,192.168.154.135:2181";
- //即超时时间,我们设置成2s
- private int sessionTimeout = 2000;
- //声明zookeeper客户端
- private ZooKeeper zkClient;
-
-
- //初始化
- // @Test
- @Before
- public void init() throws IOException {
- zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
- @Override //process中即为监听后做出的处理
- public void process(WatchedEvent watchedEvent) {
- List<String> children = null;
- try {
- children = zkClient.getChildren("/", true);
- } catch (KeeperException e) {
- e.printStackTrace();
- } catch (InterruptedException e) {
- e.printStackTrace();
- }
- System.out.println("-------------------------");
- for (String child : children) {
- System.out.println(child);
- }
- System.out.println("-------------------------");
-
- }
- });
- }
-
-
- //创建节点
- @Test
- public void create() throws InterruptedException, KeeperException {
- //public String create(String path, byte[] data, List<ACL> acl, CreateMode createMode)
- //上图中从左到右的参数分别对应着:你所要创建的节点的名字,节点的值,节点的权限,节点的类型(持久有序,持久无序,临时有序,临时无序)
- zkClient.create("/class", "LiHua".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
- }
-
-
-
- //监听节点
- @Test
- public void getChildren() throws InterruptedException, KeeperException {
-
- //正常一次监听只会生效一次,因此我们设置延时监听,确保能够持续监听节点的变化。
- Thread.sleep(Long.MAX_VALUE);
- }
-
- //判断节点是否存在
- @Test
- public void status() throws InterruptedException, KeeperException {
- Stat status = zkClient.exists("/class", false);
- System.out.println(status == null ? "no exist" : "exist");
- }
-
- }


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