1.Feign

　　之前使用的是Ribbon+RestTemplate呼叫，通過的是微服務的名字進行呼叫，實現負載均衡

　　但是為了滿足介面程式設計，提供了Feign

2.實現

2.1引入座標

　　在 ms-common-api 和 ms-consumer-dept-80-feign 引入座標

        <!--feign 客戶端負載均衡-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <
 
artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>

2.2 在 ms-common-api 實現呼叫

package org.maple.service;

import org.maple.entity.Dept;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import
 
 org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;

import java.util.List;

/**
 * @author mapleins
 * @Date 2019-01-12 23:10
 * @Desc 通過介面和註解 面向介面程式設計訪問微服務
 **/
@FeignClient("ms-provider-dept")
 
public interface DeptClientService {

    @PostMapping("/dept/add")
    boolean add(@RequestBody Dept dept);

    @GetMapping("/dept/get/{id}")
    Dept get(@PathVariable("id") Long id);

    @GetMapping("/dept/list")
    List<Dept> list();

}

2.3修改 dept-80-feign的啟動類

package org.maple;

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

/**
 * @author mapleins
 * @Date 2019-01-09 20:26
 * @Desc
 **/
@SpringBootApplication
@EnableEurekaClient 
@EnableFeignClients(basePackages = {"org.maple.service"}) //掃描ms-common-api中的service包
public class App_Consumer_Dept_80_Feign {

    public static void main(String[] args) {
        SpringApplication.run(App_Consumer_Dept_80_Feign.class, args);
    }
}

2.4 controller層

這樣就相當於不是去呼叫微服務去程式設計，而是通過controller呼叫service層，實現介面程式設計，並且自帶ribbon的輪詢演算法

package org.maple.controller;

import org.maple.entity.Dept;
import org.maple.service.DeptClientService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;


/**
 * @author mapleins
 * @Date 2019-01-09 20:10
 * @Desc
 **/
@RestController
public class DeptController_Consumer {

    @Autowired
    private DeptClientService service;

    @GetMapping("/consumer/dept/get/{id}")
    public Dept get(@PathVariable("id") Long id){
        return service.get(id);
    }

    @GetMapping("/consumer/dept/list")
    public List<Dept> list(){
        return service.list();
    }

    @PostMapping("/consumer/dept/add")
    public boolean add(Dept dept){
        return service.add(dept);
    }

}