OpenFeign使用步驟

一般來說就是介面+註解：微服務呼叫介面+@FeignClient

Feign在消費端使用

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在專案中實踐：

1、新建cloud-consumer-feign-order80

2、改POM

    <!--openfeign-->
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>com.sl.springcloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>${project.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

3、寫YML

server:
  port: 80
eureka:
  client:
    register-with-eureka: false
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka, http://eureka7002.com:7002/eureka

4、主啟動類(@EnableFeignClients)

@SpringBootApplication
@EnableFeignClients
public class OrderFeignMain80 {
    public static void main(String[] args) {
        SpringApplication.run(OrderFeignMain80.class,args);
    }
}

5、業務類
①新建PaymentFeignService介面並新增註解@FeignClient
這個Service裡面的方法就是生產者的Controller裡面的方法。
即Controller(consumer)—>Service(Feign)–>Controller(Provider)

@Component
@FeignClient(value = "CLOUD-PAYMENT-SERVICE")
public interface PaymentFeignService {
    /**
     * 相當於在消費者Controller和生產者Controller中加了一層Service
     *
     * Controller(consumer)--->Service(Feign)-->Controller(Provider)
     * @param id
     * @return
     */
    @GetMapping(value = "/payment/get/{id}")
    public CommonResult getPaymentById(@PathVariable("id") Long id);

}

②控制層Controller

@RestController
public class OrderFeignController {

    @Resource
    private PaymentFeignService paymentFeignService;

    @GetMapping(value = "/consumer/payment/get/{id}")
    public CommonResult<payment> getPaymentById(@PathVariable("id") Long id){
        return paymentFeignService.getPaymentById(id);
    }



}

6、測試

①先啟動2個eureka叢集7001/7002
②再啟動2個微服務8001/8002
③啟動OpenFeign80
④http://localhost/consumer/payment/get/31

注意：Feign自帶負載均衡配置項