环境准备
zookeeper准备
首先你需要一个zookeeper服务器，或者是一个zookeeper集群。我已经准备好了一个zookeeper集群，如图：
当然一个单节点的zookeeper也可以搭建分布式锁。如果你还没有zookeeper，那么你可以参考我写的搭建zookeeper集群的文章：https://blog.csdn.net/m0_51510236/article/details/132834141
SpringBoot项目准备
这个步骤比较简单，我的代码已经提交至公共代码仓库，代码仓库地址为：https://gitcode.net/m0_51510236/zookeeper-distribution-lock
代码编写
pom.xml依赖文件
首先我们需要添加一下SpringCloudZookeeper的依赖，因为是只使用到了SpringCloud的zookeeper模块，所以没必要引入整个SpringCloud，如果你已经引入了整个SpringCloud，那么就没必要引入该模块了，如图：
其次我们要在dependency里面引入zookeeper的依赖：
<!-- Zookeeper 客户端 --> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-zookeeper</artifactId> </dependency> <!-- Zookeeper 分布式锁 --> <dependency> <groupId>org.apache.curator</groupId> <artifactId>curator-recipes</artifactId> </dependency>
然后我们还需要引入SpringBoot测试模块的依赖：
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency>
整体pom.xml文件：
<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.6.15</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>city.yueyang</groupId> <artifactId>zookeeper-distribution-lock</artifactId> <version>0.0.1-SNAPSHOT</version> <name>zookeeper-distribution-lock</name> <description>zookeeper分布式锁</description> <properties> <java.version>11</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency> <!-- Zookeeper 客户端 --> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-zookeeper</artifactId> </dependency> <!-- Zookeeper 分布式锁 --> <dependency> <groupId>org.apache.curator</groupId> <artifactId>curator-recipes</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <dependencyManagement> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-zookeeper-dependencies</artifactId> <version>3.1.4</version> <scope>import</scope> <type>pom</type> </dependency> </dependencies> </dependencyManagement> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>
application.yaml文件
application.yaml是SpringCloud的配置文件，我们只需要配置zookeeper的地址即可，文件内容为：
spring: cloud: zookeeper: # 可以只写一个，如果是有多个节点的zookeeper集群，那么多个节点用英文逗号隔开 connect-string: 192.168.1.181:2181,192.168.1.182:2181,192.168.1.183:2181
Runnable类
我们需要建立一个线程池来模拟多线程整合zookeeper做分布式锁，那么我们需要一个Runnable类来定义多线程的任务，java代码为：
package city.yueyang.lock.thread; import org.apache.curator.framework.recipes.locks.InterProcessMutex; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.util.concurrent.CountDownLatch; /** * <p></p> * * @author XiaoHH * @version 1.0.0 * @date 2023-09-13 星期三 20:44:59 * @file DistributionLockRunnable.java */ public class DistributionLockRunnable implements Runnable { private static final Logger log = LoggerFactory.getLogger(DistributionLockRunnable.class); /** * 分布式锁对象 */ private final InterProcessMutex lock; /** * CountDownLatch锁，避免多线程没有执行完就退出程序 */ private final CountDownLatch countDownLatch; public DistributionLockRunnable(InterProcessMutex lock, CountDownLatch countDownLatch) { this.lock = lock; this.countDownLatch = countDownLatch; } @Override public void run() { String threadName = Thread.currentThread().getName(); try { log.info("线程名：{}，尝试获取锁", threadName); // 获取锁 lock.acquire(); log.info("线程名：{}，获取锁成功，正在处理数据", threadName); Thread.sleep(1000); // 模拟处理数据睡眠一秒钟 log.info("线程名：{}，数据处理成功", threadName); } catch (Throwable e) { log.error("线程名：{}，发生了错误", threadName, e); } finally { try { // 退出锁 lock.release(); log.info("线程名：{}，锁已释放", threadName); // 锁-1 countDownLatch.countDown(); } catch (Exception e) { log.error("线程名：{}，释放锁的时候发生了错误", threadName, e); } } } }
注意下面两行代码：
lock.acquire(); // 获取锁 lock.release(); // 释放锁
代码里面日志打印已经很详细，这里就不再过多解释
测试类编写
我们编写一个测试用例来测试这个分布式锁：
package city.yueyang.lock; import city.yueyang.lock.thread.DistributionLockRunnable; import org.apache.curator.framework.CuratorFramework; import org.apache.curator.framework.recipes.locks.InterProcessMutex; import org.junit.jupiter.api.Test; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.test.context.SpringBootTest; import java.util.concurrent.*; @SpringBootTest public class ZookeeperDistributionLockApplicationTests { /** * 日志记录对象 */ private static final Logger log = LoggerFactory.getLogger(ZookeeperDistributionLockApplicationTests.class); /** * zookeeper的客户端 */ @Autowired private CuratorFramework curatorFramework; /** * zookeeper锁的路径，这也会被认为是zookeeper锁的标识 */ private static final String LOCK_PATH = "/lock/test-zookeeper-lock"; @Test public void testDistributionLock() { // 处理十个任务 final int taskAmount = 10; // 使用 CountDownLatch 锁避免多线程没有执行完程序就停止 CountDownLatch countDownLatch = new CountDownLatch(taskAmount); // 创建zookeeper的锁对象，如果第二个参数也就是path路径是一样的，那么就会被认为是同一把锁 InterProcessMutex lock = new InterProcessMutex(this.curatorFramework, LOCK_PATH); // 创建线程池 ThreadPoolExecutor executor = new ThreadPoolExecutor(taskAmount, taskAmount, 100, TimeUnit.SECONDS, new ArrayBlockingQueue<>(taskAmount)); for (int i = 0; i < taskAmount; i++) { // 创建一个任务 Runnable task = new DistributionLockRunnable(lock, countDownLatch); // 使用线程池去执行它 executor.execute(task); } try { // 等待所有的countDown锁执行完毕本线程结束 countDownLatch.await(); } catch (InterruptedException e) { log.error("countdown锁被终止了"); } finally { // 终止线程池 executor.shutdown(); } } }
创建锁对象的代码主要是下面这行：
InterProcessMutex lock = new InterProcessMutex(this.curatorFramework, "锁路径的字符串");
重点是第二个参数，是锁路径。无论new出多少个锁对象，只要锁路径的字符串是一样的，就会被zookeeper认为是同一把锁
测试代码
我们直接运行这个测试用例，可以发现都是有序的获取锁，并没有并发执行的问题，这也证明了分布式锁搭建成功：
代码已提交到公共代码仓库。代码仓库地址：https://gitcode.net/m0_51510236/zookeeper-distribution-lock
