SpringCloud下基于ZooKeeper的服務注冊與發(fā)現(xiàn)實踐

ZooKeeper作為分布式協(xié)調(diào)組件，也可以作為SpringCloud下的注冊中心進行使用

abstract.png配置ZooKeeper

通過Docker先建立一個ZooKeeper服務

#?拉取鏡像
docker?pull?zookeeper

#?創(chuàng)建?ZooKeeper?容器
docker?run?-p?2181:2181?-d?\
???--name?ZooKeeper-Service?\
???zookeeper

進入ZooKeeper容器，在/conf/zoo.cfg文件中添加下述內(nèi)容，以開啟四字命令。然后重啟ZooKeeper容器

# 開啟四字命令
4lw.commands.whitelist=*

如下所示

figure 1.jpeg

現(xiàn)在，通過ZooKeeper客戶端PrettyZoo執(zhí)行四字命令envi來進一步明確ZooKeeper版本信息——其版本為3.6.2，如下所示

figure 2.jpeg搭建服務提供者

POM依賴

這里我們建立一個SpringBoot項目——payment，作為服務的提供者。對于ZooKeeper作為注冊中心的場景，在SpringCloud直接使用spring-cloud-starter-zookeeper-discovery依賴即可。需要注意的是：

1. Zookeeper依賴的版本需與我們的所使用服務端版本保持一致, 故需從spring-cloud-starter-zookeeper-discovery排除該依賴，并顯式引入3.6.2版本的Zookeeper依賴
2. Zookeeper日志依賴與SpringBoot日志依賴沖突, 故需這里排除前者的日志依賴

<dependencyManagement>
??<dependencies>

????
????<dependency>
??????<groupId>org.springframework.bootgroupId>
??????<artifactId>spring-boot-dependenciesartifactId>
??????<version>2.2.2.RELEASEversion>
??????<type>pomtype>
??????<scope>importscope>
????dependency>

????
????<dependency>
??????<groupId>org.springframework.cloudgroupId>
??????<artifactId>spring-cloud-dependenciesartifactId>
??????<version>Hoxton.SR1version>
??????<type>pomtype>
??????<scope>importscope>
????dependency>

??dependencies>
dependencyManagement>

<dependencies>

??

??<dependency>
????<groupId>org.springframework.cloudgroupId>
????<artifactId>spring-cloud-starter-zookeeper-discoveryartifactId>
????<exclusions>
??????
??????<exclusion>
????????<groupId>org.apache.zookeepergroupId>
????????<artifactId>zookeeperartifactId>
??????exclusion>
????exclusions>
??dependency>

??<dependency>
????<groupId>org.apache.zookeepergroupId>
????<artifactId>zookeeperartifactId>
????<version>3.6.2version>
????<exclusions>
??????
??????<exclusion>
????????<groupId>org.slf4jgroupId>
????????<artifactId>slf4j-log4j12artifactId>
??????exclusion>
????exclusions>
??dependency>

dependencies>

配置文件

配置文件中只需通過spring.cloud.zookeeper.connect-string配置項指定ZooKeeper服務地址信息即可

#?通用配置
spring:
????application:
????????name:?payment
????profiles:
????????active:?payment3

---
#?payment服務實例3配置
spring:
????profiles:?payment3
????cloud:
????????zookeeper:
????????????#?ZooKeeper?地址信息
????????????connect-string:?127.0.0.1:2181

server:
????port:?8003

Java實現(xiàn)

簡便起見，這里我們直接提供了一個Controller，用于測試

@RestController
@RequestMapping("pay")
public?class?PaymentController?{

????@Value("${server.port}")
????private?String?serverPort;???

????@GetMapping("/hello")
????public?String?hello(@RequestParam?String?name)?{
????????String?msg?=?"[Payment?Service-"+?serverPort?+"]:?"?+?name;
????????return?msg;
????}

}

然后在啟動類上添加 @EnableDiscoveryClient 注解即可

import?org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@SpringBootApplication
@EnableDiscoveryClient
public?class?PaymentApplication?{
????public?static?void?main(String[]?args)?{
????????SpringApplication.run(PaymentApplication.class,?args);
????}
}

搭建服務消費者

配置文件

類似地，我們還建立一個SpringBoot項目——order，作為服務消費者。由于其POM依賴與服務提供者的POM依賴并無二致。故這里不再贅述，直接復制即可。配置文件同理，如下所示

spring:
????application:
????????name:?order
????profiles:
????????active:?order2

---
#?order服務實例2配置
spring:
????profiles:?order2
????cloud:
????????zookeeper:
????????????#?ZooKeeper?地址信息
????????????connect-string:?127.0.0.1:2181

server:
????port:?81

Java實現(xiàn)

首先聲明創(chuàng)建RestTemplate實例。一個是普通的RestTemplate實例，一個則是添加了 @LoadBalanced 注解的RestTemplate實例。前者可進行基于IP、Port服務調(diào)用；后者由于添加了 @LoadBalanced 注解，其一方面可進行基于服務名的服務調(diào)用，另一方面支持負載均衡

@Configuration
public?class?RestTemplateConfig?{

????/**
?????*?普通的restTemplate實例,?可利用IP、Port調(diào)用服務
?????*?@return
?????*/
????@Bean
????public?RestTemplate?restTemplate1()?{
????????return?new?RestTemplate();
????}

????/**
?????*?@LoadBalanced?注解作用:
?????*???1.?基于服務名調(diào)用的restTemplate實例
?????*???2.?支持負載均衡
?????*?@return
?????*/
????@Bean
????@LoadBalanced
????public?RestTemplate?restTemplate2()?{
????????return?new?RestTemplate();
????}

}

然后通過Controller調(diào)用Payment服務接口。下面展現(xiàn)了 傳統(tǒng)地基于IP、Port信息 和 基于服務名 兩種形式的服務調(diào)用

@RestController
@RequestMapping("order")
public?class?OrderController?{

????//?使用?固定IP、Port
????public?static?final?String?PAYMENT_URL_1?=?"http://localhost:8003";

????//?使用?注冊中心的服務名
????public?static?final?String?PAYMENT_URL_2?=?"http://payment";

????@Qualifier("restTemplate1")
????@Autowired
????private?RestTemplate?restTemplate1;

????@Qualifier("restTemplate2")
????@Autowired
????private?RestTemplate?restTemplate2;

????@GetMapping("/test1")
????public?String?test1(@RequestParam?String?name)?{
????????String?msg?=?restTemplate1.getForObject(PAYMENT_URL_1?+"/pay/hello?name={1}",?String.class,?name);
????????String?result?=?"[Order?Service?#test1]:?"?+?msg;
????????return?result;
????}

????@GetMapping("/test2")
????public?String?test2(@RequestParam?String?name)?{
????????String?msg?=?restTemplate2.getForObject(PAYMENT_URL_2?+"/pay/hello?name={1}",?String.class,?name);
????????String?result?=?"[Order?Service?#test2]:?"?+?msg;
????????return?result;
????}

}

最后，在啟動類上添加 @EnableDiscoveryClient 注解

import?org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@SpringBootApplication
@EnableDiscoveryClient
public?class?OrderApplication?{
????public?static?void?main(String[]?args)?{
????????SpringApplication.run(OrderApplication.class,?args);
????}
}

測試

啟動payment、order服務，通過ZooKeeper客戶端PrettyZoo可以看出均注冊成功

figure 3.jpeg

然后通過curl驗證測試，服務調(diào)用正常符合預期，如下所示

figure 4.jpeg參考文獻

1. Spring微服務實戰(zhàn) John Carnell著