OpenFeign实现服务调用—SpringCloud（H版）微服务学习教程（22）

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章
目
录

• 第1步：创建Module
• 第2步：改pom
• 第3步：写yml
• 第4步：主启动
• 第5步：业务类
• 第6步：测试

通过之前的学习，我们知道可以使用OpenFeign代替Ribbon+RestTemplate实现服务的负载均衡调用，下面我们来准备好演示环境。

第1步：创建Module

我们在mscloud下创建名为cloud-consumer-feign-order80模块

第2步：改pom

pom.xml如下：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>mscloud</artifactId>
        <groupId>com.panziye.springcloud</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>cloud-consumer-feign-order80</artifactId>
    <dependencies>
        <!--   OpenFign     -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <!--   eureka client     -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>

        <!--  引入自定义的api通用包，可以使用支付Payment等Entity      -->
        <dependency>
            <groupId>com.panziye.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>

</project>

我们除了Eureka依赖还添加了OpenFeign依赖（如果你的依赖报错，请加入版本号），我们打开依赖查看，发现OpenFeign依赖以及集成了Ribbon

第3步：写yml

application.yml如下：

server:
  port: 80
 
spring:
  application:
    name: cloud-order-feign-service
 
eureka:
  client:
    #表示是否将自己注册进eureka服务中心，默认true
    register-with-eureka: false
    #表示是否从EurekaServer抓取已有注册信息，默认true。单节点无所谓，集群必须设置true才能配合ribbon使用负载均衡
    fetch-registry: true
    service-url:  #指向eureka集群
      defaultZone: http://eureka7001.com:7001/eureka,http://eureka7002.com:7002/eureka,http://eureka7003.com:7003/eureka

第4步：主启动

新建OrderFeignMain80主启动类：

package com.panziye.springcloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.openfeign.EnableFeignClients;

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

提示：@EnableFeignClients用于激活OpenFeign客户端

第5步：业务类

1）在service包下新建OrderFeignService接口：

注意：这里定义的接口应与服务提供者的service层接口对应，我这里只演示get，另外其返回值与服务提供者的controller对应，这就是我们希望的面向微服务接口编程。

package com.panziye.springcloud.service;

import com.panziye.springcloud.entities.CommonResult;
import com.panziye.springcloud.entities.Payment;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;

@Component
@FeignClient(value = "CLOUD-PAYMENT-SERVICE")
public interface OrderFeignService {
    //匹配服务提供者请求Mapping
    @GetMapping(value = "/payment/get/{id}")
    public CommonResult<Payment> getPaymentById(@PathVariable("id") Long id);
}

注意：@FeignClient注解表明此接口使用OpenFeign发请求，value指定服务提供者应用名称，@PathVariable不能丢

2）在controller包下新建OrderFeignController类：

package com.panziye.springcloud.controller;

import com.panziye.springcloud.entities.CommonResult;
import com.panziye.springcloud.entities.Payment;
import com.panziye.springcloud.service.OrderFeignService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;

@RestController
@Slf4j
public class OrderFeignController {
    @Resource
    private OrderFeignService orderFeignService;

    @GetMapping("/consumer/payment/get/{id}")
    public CommonResult<Payment> getPayment(@PathVariable("id") Long id){
        return orderFeignService.getPaymentById(id);
    }
}

第6步：测试

我们先启动7001、7002、7003这3个eureka注册中心，再启动8001和8002这两个服务提供者，最后启动我们新建的OrderFeignMain80，访问http://localhost/consumer/payment/get/1测试，发现正常访问，默认使用的是Ribbon的轮询策略。