1.服務端

1.1 服務端（檔案接收方）介面：

    @ApiOperation(value = "儲存備份檔案", notes = "儲存備份檔案", consumes = MediaType.MULTIPART_FORM_DATA_VALUE, produces = "application/json")
    @PostMapping(value = "/saveBackFile")
    @ResponseBody
    public Response saveBackFile(
            @ApiParam(value = "檔案附加資訊") @Valid BackupFileAttachInfo fileInfo,
            @ApiParam(value = "備份檔案") @RequestPart("file") MultipartFile file);
 

1.2 服務端增加一個物件注入（可通過一個配置類的方法注入），配置檔案上傳臨時目錄

    @Bean
    public MultipartConfigElement multipartConfigElement() {
        MultipartConfigFactory factory = new MultipartConfigFactory();
        factory.setLocation("d:/"); //配置檔案上傳臨時目錄
        return factory.createMultipartConfig();
    }

2.客戶端

2.0 SpringBoot啟動類要增加  @EnableFeignClients 註解，否則，FeignClient不會生效！

2.1 首先pom中要增加feign和eureka等的依賴，還要加入下面的依賴：

       <!--新增Springboot對MultipartFile的類庫支援，在spring-test包中-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>5.1.3.RELEASE</version>
            <scope>compile</scope>
        </dependency>
        <!--spring feign form 表單提交相關-->
        <dependency>
            <groupId>io.github.openfeign.form</groupId>
            <artifactId>feign-form-spring</artifactId>
            <version>3.4.1</version>
        </dependency>
        <!--feign form 表單提交相關-->
        <dependency>
            <groupId>io.github.openfeign.form</groupId>
            <artifactId>feign-form</artifactId>
            <version>3.4.1</version>
        </dependency>
        <!--檔案上傳相關依賴-->
        <dependency>
            <groupId>commons-fileupload</groupId>
            <artifactId>commons-fileupload</artifactId>
            <version>1.3.3</version>
        </dependency>
 

2.2 FeignClient

@Service
@FeignClient(name = "MODEL-LIB",value="MODEL-LIB" , configuration = FeignMultipartSupportConfig.class,url="http://127.0.0.1:8080/file") 
public interface ModellibFeignClient {
    @PostMapping(value = "/saveBackFile" ,consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    @ResponseBody
    public BaseResponsev1 saveBackFile(
            @ApiParam(value = "租戶id") @RequestParam("tenant") String tenant,
            @ApiParam(value = "project") @RequestParam("project") String project,
            @ApiParam(value = "namespace") @RequestParam("namespace") String namespace,
            @ApiParam(value = "username") @RequestParam("username") String username,
            @ApiParam(value = "備份檔案")  @RequestPart("file")  MultipartFile file);
}

2.3 Feign配置類，主要是對MultipartFile上傳時的編碼相關：FeignMultipartSupportConfig，如果不配置這個類，預設會將檔案也編譯成json，導致報錯：

@Configuration
public class FeignMultipartSupportConfig {
    @Autowired
    private ObjectFactory<HttpMessageConverters> messageConverters;

    @Bean
    @Primary
    @Scope("prototype")
    public Encoder multipartFormEncoder() {
        return new SpringFormEncoder(new SpringEncoder(messageConverters));
    }

    @Bean
    public feign.Logger.Level multipartLoggerLevel() {
        return Logger.Level.FULL;
    }
}

2.4 呼叫FeignClient

	File file = new File("d://lq.jpg");

	MultipartFile multipartFile = null;

	DiskFileItem fileItem = (DiskFileItem) new DiskFileItemFactory().createItem("file", //這個file對應feignClient中的MultipartFile引數名，寫錯就會報400 ："message":"Required request part 'file' is not present"這個錯誤，切記！
	        MediaType.MULTIPART_FORM_DATA_VALUE, true, file.getName());

	try (InputStream input = new FileInputStream(file); OutputStream os = fileItem.getOutputStream()) {
	    IOUtils.copy(input, os);
	} catch (Exception e) {
	    throw new IllegalArgumentException("Invalid file: " + e, e);
	}

	multipartFile = new CommonsMultipartFile(fileItem);

	System.out.println(multipartFile);
	BaseResponsev1 response = modellibFeignClient.saveBackFile("lq", "zwr", "zhh", "zhh1", multipartFile);

完全照此步驟操作，可保證FeignClient上傳MultipartFile成功！

至此完成！