如題所示，程式碼如下

 1 -- 1. client
 2 @FeignClient(name="microservice-provider-user")
 3 public interface UserFeignClient {
 4   @GetMapping("/users/{id}")
 5   User findById(@PathVariable Long id);
 6 }
 7 
 8 -- 2. 控制層
 9 @RequestMapping("/movies")
10 @RestController
11 public class MovieController {
12     @Autowired
 
13     private RestTemplate restTemplate;
14 
15     @Autowired
16     private UserFeignClient userFeignClient;
17 
18     @GetMapping("/users/{id}")
19     public User findById(@PathVariable Long id) {
20         // 這裡用到了RestTemplate的佔位符能力
21         User user = userFeignClient.findById(id);
22         //
 
 ...電影微服務的業務...
23         return user;
24     }
25 }
26 
27 -- 3. 啟動類
28 @SpringBootApplication
29 @EnableEurekaClient
30 @EnableFeignClients("com.caiya.movie.utils")
31 public class FeignMovieApplication {
32     @Bean
33     public RestTemplate restTemplate() {
34         return new RestTemplate();
 
35     }
36 
37     public static void main(String[] args) {
38         SpringApplication.run(FeignMovieApplication.class, args);
39     }
40 }

百度了下，得到的結果是

　　1. springboot 啟動類註解 @EnableFeignClients 沒有寫掃描包 （對比筆者自己的工程，client是在 啟動類所在包的子包下，理論上不是這個問題
不過還是按提示修改後，一樣報錯...

　　2. 筆者自己設定了多個模組，包名存在一致的情況，為了排除這個情況導致，修改包名後還是一樣的問題

最終解決方案：
　　還是 stackoverflow 牛皮，google一下就出來答案了

原因是我在複製網上教程時候，直接把 @PathVariable("id") 裡面的id省略了， 自以為id可寫可不寫

@FeignClient(name = "microservice-provider-user")
public interface UserFeignClient {
@GetMapping("/users/{id}")
　　User findById(@PathVariable("id") Long id); // 此處（“id”）必寫
}

不過這是feign的bug，後續的版本好像是解決了

解答原文及地址： https://stackoverflow.com/questions/49415197/spring-boot-2-unsatisfied-dependency-on-feign-client-when-autowired-for-servic

There was an issue in feign client before. I guess you are experiencing the same maybe because you are using an old version but what you should do is including the pathVariable name in your @PathVariable annotation like this 
    @RequestMapping(value = "/hello/{name}", method = RequestMethod.GET)
    String hello(@PathVariable(value = "name") String name);

You can find the details from 
https://github.com/spring-cloud/spring-cloud-netflix/issues/861