02 Spring Cloud Netflix Eureka实现服务注册与发现
Spring Cloud官网: https://spring.io/projects/spring-cloud
本篇主要讲Spring Cloud Netflix中的Eureka，参考内容如下
文章内容会尽量参考官方文档。
1 注册中心（Eureka Server）
完整代码地址：https://github.com/sxpujs/spring-cloud-examples/tree/master/netflix/netflix-eureka-server
1 maven依赖增加 netflix-eureka-server
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
</dependency>
2 配置文件 application.yml
server:
port: 8761
eureka:
instance:
hostname: localhost
client:
registerWithEureka: false
fetchRegistry: false
serviceUrl:
defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
3 Application启动类，增加@EnableEurekaServer注解
@SpringBootApplication
@EnableEurekaServer
public class NetflixEurekaServerApplication {
public static void main(String[] args) {
SpringApplication.run(NetflixEurekaServerApplication.class, args);
}
}
4 启动服务，在浏览器打开如下地址：http://localhost:8761/，页面如下：
2 创建服务提供者
完整代码参考：https://github.com/sxpujs/spring-cloud-examples/tree/master/netflix/netflix-eureka-client-provider
1 maven依赖增加 netflix-eureka-client
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
2 配置application.yml
eureka:
client:
serviceUrl:
defaultZone: http://localhost:8761/eureka/
spring:
application:
name: provider ## 应用程序名称，后面会在消费者中用到
server:
port: 8000
3 Application启动类与hello接口
@SpringBootApplication
@RestController
@Slf4j
public class NetflixEurekaClientProviderApplication {
@RequestMapping("/")
public String home() {
return "Hello world";
}
@Autowired
private DiscoveryClient discoveryClient;
@RequestMapping(value = "/hello")
public String hello(){
List<String> services = discoveryClient.getServices();
for(String s : services){
log.info(s);
}
return "hello spring cloud!";
}
public static void main(String[] args) {
SpringApplication.run(NetflixEurekaClientProviderApplication.class, args);
}
}
4 启动项目，正常情况下就注册到了 Eureka 注册中心，打开 Eureka 控制台，会看到已经出现了这个服务。
curl localhost:8000/hello
结果: hello spring cloud!
3 创建服务消费者
完整代码参考：https://github.com/sxpujs/spring-cloud-examples/tree/master/netflix/netflix-eureka-client-consumer
1 maven依赖增加 netflix-eureka-client, spring-cloud-starter-openfeign等
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
2 配置application.yml
eureka:
client:
serviceUrl:
defaultZone: http://localhost:8761/eureka/
spring:
application:
name: consumer ## 应用程序名称
server:
port: 9000
3 Application启动类
@SpringBootApplication
@RestController
@EnableEurekaClient
@EnableFeignClients
public class NetflixEurekaClientConsumerApplication {
/**
* 注入 RestTemplate
* 并用 @LoadBalanced 注解，用负载均衡策略请求服务提供者
* 这是 Spring Ribbon 的提供的能力
* @return
*/
@LoadBalanced
@Bean
public RestTemplate restTemplate() {
return new RestTemplate();
}
@RequestMapping("/")
public String home() {
return "Hello world";
}
public static void main(String[] args) {
SpringApplication.run(NetflixEurekaClientConsumerApplication.class, args);
}
}
4 创建一个服务接口类，这是 Feign 的使用方式，详细的用法可以查一下 Spring Cloud Feign 相关文档
/**
* IHelloService
* 配置服务提供者：provider 是服务提供者的 application.name
*/
@FeignClient("provider")
public interface IHelloService {
@RequestMapping(value = "/hello")
String hello();
}
5 创建一个 Controller 用于调用服务
@RestController
public class ConsumerController {
@Autowired
private RestTemplate restTemplate;
@Autowired
private IHelloService helloService;
private static final String applicationName = "provider";
@RequestMapping(value = "commonRequest")
public Object commonRequest(){
String url = "http://"+ applicationName +"/hello";
return restTemplate.getForObject(url,String.class);
}
@RequestMapping(value = "feignRequest")
public Object feignRequest(){
return helloService.hello();
}
}
其中 feignRequest 方法是使用了 Feign 的方式调用服务接口；
commonRequest 方法是用 RestTemplate 提供的方法调用服务接口；
6 启动服务，测试接口。
curl localhost:9000/commonRequest
结果: hello spring cloud!
curl localhost:9000/feignRequest
结果: hello spring cloud!
