這篇文章主要介紹了spring boot2X Consul如何使用Feign實現服務呼叫,文中通過示例程式碼介紹的非常詳細，對大家的學習或者工作具有一定的參考學習價值,需要的朋友可以參考下

服務呼叫有兩種方式：

　　A.使用RestTemplate 進行服務呼叫

　　B.使用Feign 進行宣告式服務呼叫

上一次寫了使用RestTemplate的方式，這次使用Feign的方式實現

服務註冊發現中心使用Consul

啟動Consul

consul agent -dev

spring boot 版本 2.2.1.RELEASE

1.服務端

provider

（1）新增依賴

<properties>
  <java.version>1.8</java.version>
  <spring-cloud.version>Greenwich.SR3</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-consul-discovery</artifactId>
  </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>

（2）修改配置

server.port=8010

spring.application.name=provider
spring.cloud.consul.host=localhost
spring.cloud.consul.port=8500
spring.cloud.consul.discovery.health-check-path=/actuator/health
spring.cloud.consul.discovery.service-name=service-provider
spring.cloud.consul.discovery.heartbeat.enabled=true

management.endpoints.web.exposure.include=*
management.endpoint.health.show-details=always

（3）測試方法

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

}

provider1

修改埠為8011

修改測試方法

package com.xyz.provider1.controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class demoController {
  @RequestMapping("/hello")
  public String Hello(){
    return "hello,another provider";
  }
}

啟動provider和provider1

2.客戶端

customer

（1）新增依賴

<properties>
   <java.version>1.8</java.version>
   <spring-cloud.version>Greenwich.SR4</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-consul-discovery</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-openfeign</artifactId>
    </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>

(2)配置

server.port=8015
spring.application.name=xyz-comsumer
spring.cloud.consul.host=localhost
spring.cloud.consul.port=8500
spring.cloud.consul.discovery.register=false
spring.cloud.consul.discovery.health-check-url=/actuator/health
spring.cloud.consul.discovery.heartbeat.enabled=true
management.endpoints.web.exposure.include=*
management.endpoint.health.show-details=always

（3）修改啟動類

添加註解 @EnableFeignClients，開啟掃描Spring Cloud Feign客戶端的功能

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

（4）新增Feign介面

添加註解@FeignClient(name = "provider")

provider是要呼叫的服務名

說明：

　　新增跟呼叫目標方法一樣的方法宣告，必須跟目標方法的定義一致

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）服務呼叫

注入剛才宣告的ProviderService，就可以像本地方法一樣進行呼叫了

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;
@RestController
public class FeignController {
  @Autowired
  private ProviderService providerService;
  @RequestMapping("/call")
  public String call() {
    return providerService.hello();
  }
}

啟動customer

訪問http://localhost:8015/call

交替返回結果

hello,provider 或 hello,another provider

以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支援我們。