5 Zookeeper系列：使用Zookeeper作为注册中心(zookeeper和eureka的区别)

服务注册引入相关依赖：
<?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>2.4.5</version><relativePath/>  </parent> <groupId>com.example</groupId> <artifactId>zkdemo</artifactId> <version>0.0.1-SNAPSHOT</version> <name>zkdemo</name> <description>Demo project for Spring Boot</description> <properties><java.version>1.8</java.version><spring-cloud.version>2020.0.2</spring-cloud.version> </properties> <dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-zookeeper-discovery</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-dependencies</artifactId><version>${spring-cloud.version}</version><type>pom</type><scope>import</scope></dependency></dependencies> </dependencyManagement> <build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins> </build></project>配置文件application.yml：
spring:cloud:zookeeper:# Zookeeper服务器地址，集群则以逗号分隔connect-string: localhost:2181application:name: zkdemo# 使用随机端口server:port: 0主程序类ZkdemoApplication：
@SpringBootApplicationpublic class ZkdemoApplication { public static void main(String[] args) {SpringApplication.run(ZkdemoApplication.class, args); }}由于配置了使用随机端口，这里直接启动三个ZkdemoApplication运行三个zkdemo服务示例。
启动成功后，在zookeeper中查看节点的变化，会发现在根节点下多出来一个services节点，services节点下是以服务名称命名的服务节点，服务节点下是该服务的实例节点。
[zk: localhost:2181(CONNECTED) 96] ls -R / //services/services/zkdemo/services/zkdemo/2030bca0-db25-411d-b1f5-84c790bd1d6f/services/zkdemo/208834cf-e7e4-496e-a5c0-afcbb78e120f/services/zkdemo/2c4177e1-20fd-4c66-9ee0-eaf21253039d实例节点中存储了服务名称、ip地址、端口号、实例ID等相关信息：
[zk: localhost:2181(CONNECTED) 97] get /services/zkdemo/208834cf-e7e4-496e-a5c0-afcbb78e120f {"name":"zkdemo","id":"208834cf-e7e4-496e-a5c0-afcbb78e120f","address":"localhost","port":64514,"sslPort":null,"payload":{"@class":"org.springframework.cloud.zookeeper.discovery.ZookeeperInstance","id":"zkdemo","name":"zkdemo","metadata":{"instance_status":"UP"}},"registrationTimeUTC":1619424602784,"serviceType":"DYNAMIC","uriSpec":{"parts":[{"value":"scheme","variable":true},{"value":"://","variable":false},{"value":"address","variable":true},{"value":":","variable":false},{"value":"port","variable":true}]}}[zk: localhost:2181(CONNECTED) 98] get /services/zkdemo/2030bca0-db25-411d-b1f5-84c790bd1d6f{"name":"zkdemo","id":"2030bca0-db25-411d-b1f5-84c790bd1d6f","address":"localhost","port":64401,"sslPort":null,"payload":{"@class":"org.springframework.cloud.zookeeper.discovery.ZookeeperInstance","id":"zkdemo","name":"zkdemo","metadata":{"instance_status":"UP"}},"registrationTimeUTC":1619424361059,"serviceType":"DYNAMIC","uriSpec":{"parts":[{"value":"scheme","variable":true},{"value":"://","variable":false},{"value":"address","variable":true},{"value":":","variable":false},{"value":"port","variable":true}]}}[zk: localhost:2181(CONNECTED) 99] get /services/zkdemo/2c4177e1-20fd-4c66-9ee0-eaf21253039d{"name":"zkdemo","id":"2c4177e1-20fd-4c66-9ee0-eaf21253039d","address":"localhost","port":64475,"sslPort":null,"payload":{"@class":"org.springframework.cloud.zookeeper.discovery.ZookeeperInstance","id":"zkdemo","name":"zkdemo","metadata":{"instance_status":"UP"}},"registrationTimeUTC":1619424510719,"serviceType":"DYNAMIC","uriSpec":{"parts":[{"value":"scheme","variable":true},{"value":"://","variable":false},{"value":"address","variable":true},{"value":":","variable":false},{"value":"port","variable":true}]}}通过ephemeralOwner字段可以看出，services节点和服务节点为持久节点，实例节点为临时节点：
[zk: localhost:2181(CONNECTED) 100] stat /services cZxid = 0x118ctime = Mon Apr 26 16:06:02 CST 2021mZxid = 0x118mtime = Mon Apr 26 16:06:02 CST 2021pZxid = 0x119cversion = 1dataVersion = 0aclVersion = 0ephemeralOwner = 0x0dataLength = 0numChildren = 1[zk: localhost:2181(CONNECTED) 101] stat /services/zkdemo cZxid = 0x119ctime = Mon Apr 26 16:06:02 CST 2021mZxid = 0x119mtime = Mon Apr 26 16:06:02 CST 2021pZxid = 0x11ecversion = 3dataVersion = 0aclVersion = 0ephemeralOwner = 0x0dataLength = 0numChildren = 3[zk: localhost:2181(CONNECTED) 102] stat /services/zkdemo/2030bca0-db25-411d-b1f5-84c790bd1d6f cZxid = 0x11actime = Mon Apr 26 16:06:02 CST 2021mZxid = 0x11amtime = Mon Apr 26 16:06:02 CST 2021pZxid = 0x11acversion = 0dataVersion = 0aclVersion = 0ephemeralOwner = 0x100000122cf000ddataLength = 514numChildren = 0当某个实例出现故障停止时，对应的临时节点也会被删除。当服务节点下所有实例节点被删除时，服务节点也会被删除。当services节点下的所有服务节点被删除时，services节点也会被删除。
服务发现通过DiscoveryClient从注册中心获取对应服务的实例列表：
@SpringBootTestclass ZkdemoApplicationTests { @Autowired private DiscoveryClient discoveryClient; @Test public void serviceUrl() {List<ServiceInstance> list = discoveryClient.getInstances("zkdemo");list.stream().forEach(obj -> System.out.println(obj.getUri().toString())); }}【5 Zookeeper系列：使用Zookeeper作为注册中心(zookeeper和eureka的区别)】输出结果：
http://localhost:64401http://localhost:64475http://localhost:64514服务调用这里就不演示了，可以使用Feign或RestTemplate进行调用。