服务调用有两种方式：

　　A.使用RestTemplate 进行服务调用

　　B.使用Feign 进行声明式服务调用

上一次写了使用RestTemplate的方式，这次使用Feign的方式实现

服务注册发现中心使用Consul

启动Consul

consul agent -dev

spring boot 版本 2.2.1.RELEASE

1.服务端

provider

（1）添加依赖

 1.8  Greenwich.SR3      org.springframework.boot    spring-boot-starter-web        org.springframework.cloud    spring-cloud-starter-consul-discovery              org.springframework.cloud      spring-cloud-dependencies      ${spring-cloud.version}      pom      import      

（2）修改配置

server.port=8010spring.application.name=providerspring.cloud.consul.host=localhostspring.cloud.consul.port=8500spring.cloud.consul.discovery.health-check-path=/actuator/healthspring.cloud.consul.discovery.service-name=service-providerspring.cloud.consul.discovery.heartbeat.enabled=truemanagement.endpoints.web.exposure.include=*management.endpoint.health.show-details=always

（3）测试方法

package com.xyz.provider.controller;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;@RestControllerpublic class demoController {  @RequestMapping("/hello")  public String Hello(){    return "hello,provider";  }}

provider1

修改端口为8011

修改测试方法

package com.xyz.provider1.controller;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;@RestControllerpublic class demoController {  @RequestMapping("/hello")  public String Hello(){    return "hello,another provider";  }}

启动provider和provider1

2.客户端

customer

（1）添加依赖

  1.8   Greenwich.SR4          org.springframework.boot      spring-boot-starter-web              org.springframework.cloud      spring-cloud-starter-consul-discovery              org.springframework.cloud      spring-cloud-starter-openfeign                      org.springframework.cloud        spring-cloud-dependencies        ${spring-cloud.version}        pom        import          

(2)配置

server.port=8015spring.application.name=xyz-comsumerspring.cloud.consul.host=localhostspring.cloud.consul.port=8500spring.cloud.consul.discovery.register=falsespring.cloud.consul.discovery.health-check-url=/actuator/healthspring.cloud.consul.discovery.heartbeat.enabled=truemanagement.endpoints.web.exposure.include=*management.endpoint.health.show-details=always

（3）修改启动类

添加注解 @EnableFeignClients，开启扫描Spring Cloud Feign客户端的功能

package com.xyz.comsumer;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.cloud.client.loadbalancer.LoadBalanced;import org.springframework.context.annotation.Bean;import org.springframework.web.client.RestTemplate;@EnableFeignClients@SpringBootApplicationpublic class ComsumerApplication {  public static void main(String[] args) {    SpringApplication.run(ComsumerApplication.class, args);  }}

（4）添加Feign接口

添加注解@FeignClient(name = "provider")

provider是要调用的服务名

说明：

　　添加跟调用目标方法一样的方法声明，必须跟目标方法的定义一致

package com.xyz.consumer.controller;import org.springframework.cloud.openfeign.FeignClient;import org.springframework.web.bind.annotation.RequestMapping;@FeignClient(name = "provider")public interface ProviderService {  @RequestMapping("/hello")  public String hello();}

（4）服务调用

注入刚才声明的ProviderService，就可以像本地方法一样进行调用了

package com.xyz.consumer.controller;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;@RestControllerpublic class FeignController {  @Autowired  private ProviderService providerService;  @RequestMapping("/call")  public String call() {    return providerService.hello();  }}

启动customer

访问http://localhost:8015/call

交替返回结果

hello,provider 或 hello,another provider