spring cloud 项目搭建 ：3、Feign接口负载均衡

写在前面

• spring cloud 项目搭建 ：1、eureka 服务治理: https://blog.youkuaiyun.com/a__int__/article/details/116791386
• spring cloud 项目搭建 ：2、ribbon客户端负载均衡: https://blog.youkuaiyun.com/a__int__/article/details/116797413
• spring cloud 项目搭建 ：4、Hystrix服务熔断: https://blog.youkuaiyun.com/a__int__/article/details/117442286

1、Feign介绍

ribbon和feign区别:

• ribbon通过微服务名字在客户端调用
• feign同过接口和注解在微服务端调用（实际上是在ribbon的基础上封装的，更简单）

2、使用Feign

2.1、往springcloud-api中添加service

在springcloud-api添加feign的依赖

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-feign</artifactId>
            <version>1.4.6.RELEASE</version>
        </dependency>

新建接口DeptClientService.java

import com.demo.bean.Dept;
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;
import org.springframework.web.bind.annotation.RequestMapping;

import java.util.List;

@Component
@FeignClient(value = "SPRINGCLOUD-PROVIDER-DEPT")
public interface DeptClientService {
    @GetMapping("/dept/get/{id}")
    public Dept get(@PathVariable("id") Long id);
    @GetMapping("/dept/get")
    public List<Dept> getList();
    @RequestMapping("/dept/add")
    public Boolean add(Dept dept);
}

2.2、新建服务消费者模块springcloud-consumer-dept-feign

新建包org.example.controller
新建类DeptConsumerController

import com.demo.bean.Dept;
import com.demo.service.DeptClientService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
public class DeptConsumerController {
    @Autowired
    private DeptClientService service = null ;
    @RequestMapping("consumer/dept/get/{id}")
    public Dept get(@PathVariable("id") Long id){
        return this.service.get(id);
    }
    @RequestMapping("consumer/dept/add")
    public Boolean add(Dept dept){
        return this.service.add(dept);
    }
    @RequestMapping("consumer/dept/get")
    public List<Dept> getList(){
        return this.service.getList();
    }
}

新建启动类ConsumerApplication_Feign

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

@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients(basePackages = {"com.demo"})
public class ConsumerApplication_Feign {
    public static void main(String[] args) {
        SpringApplication.run(ConsumerApplication_Feign.class,args);
    }
}

新建配置文件application.yml

server.port: 80
# eureka配置
eureka:
  client:
    register-with-eureka: false # 服务消费者，不需要往注册中心注册
    service-url:
      defaultZone: http://127.0.0.1:7001/eureka/,http://127.0.0.2:7002/eureka/,http://127.0.0.3:7003/eureka/

pom.xml

<?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>clouddemo</artifactId>
        <groupId>org.example</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>springcloud-consumer-dept-feign</artifactId>

    <dependencies>
        <!-- 导入我们自己的模块 -->
        <dependency>
            <groupId>org.example</groupId>
            <artifactId>springcloud-api</artifactId>
            <version>1.0-SNAPSHOT</version>
            <scope>compile</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework.cloud/spring-cloud-starter-ribbon -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-ribbon</artifactId>
            <version>1.4.6.RELEASE</version>
        </dependency>
        <!--erueka的依赖也需要-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
            <version>1.4.6.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-feign</artifactId>
            <version>1.4.6.RELEASE</version>
        </dependency>
    </dependencies>

</project>

2.3、启动、测试

分别启动下面这几个模块

访问http://127.0.0.1/consumer/dept/get