1.添加配置类

@Configuration
public class FeignSupportConfig {

    @Bean
    public Encoder feignFormEncoder() {
        return new FeignSpringFormEncoder();
    }

}

2.重写SpringFormEncoder

发现网上很多博文都是重写FormEncoder类,试了下没有效果,而且会引发其他的问题.
研究下了源码,发现了SpringFormEncoder类可以使用.

/**
 * 扩展FormEncoder支持多文件上传
 */
public class FeignSpringFormEncoder extends SpringFormEncoder {

    /**
     * Constructor with the default Feign's encoder as a delegate.
     */
    public FeignSpringFormEncoder() {
        this(new Encoder.Default());
    }


    /**
     * Constructor with specified delegate encoder.
     *
     * @param delegate delegate encoder, if this encoder couldn't encode object.
     */
    public FeignSpringFormEncoder(Encoder delegate) {
        super(delegate);

        MultipartFormContentProcessor processor = (MultipartFormContentProcessor) getContentProcessor(ContentType.MULTIPART);
        processor.addWriter(new SpringSingleMultipartFileWriter());
        processor.addWriter(new SpringManyMultipartFilesWriter());
    }

    @Override
    public void encode (Object object, Type bodyType, RequestTemplate template) throws EncodeException {
        if (bodyType.equals(MultipartFile[].class)) {
          // 主要是改造这里
            val  files = (MultipartFile[]) object;
            if(files != null) {
                val data = Collections.singletonMap(files.length == 0 ? "" : files[0].getName(), object);
                super.encode(data, MAP_STRING_WILDCARD, template);
            }
        } else if (bodyType.equals(MultipartFile.class)) {
            val file = (MultipartFile) object;
            val data = singletonMap(file.getName(), object);
            super.encode(data, MAP_STRING_WILDCARD, template);
        } else if (isMultipartFileCollection(object)) {
            val iterable = (Iterable<?>) object;
            val data = new HashMap<String, Object>();
            for (val item : iterable) {
                val file = (MultipartFile) item;
                data.put(file.getName(), file);
            }
            super.encode(data, MAP_STRING_WILDCARD, template);
        } else {
            super.encode(object, bodyType, template);
        }
    }

    private boolean isMultipartFileCollection (Object object) {
        if (!(object instanceof Iterable)) {
            return false;
        }
        val iterable = (Iterable<?>) object;
        val iterator = iterable.iterator();
        return iterator.hasNext() && iterator.next() instanceof MultipartFile;
    }
}

3.文件上传接口

/**
 * 文件操作Feign接口
 */
@FeignClient(
        value = "file-service",
        path = "/file",
        fallback = FileOperationClientFallback.class,
        configuration = FeignSupportConfig.class)
public interface IFileOperationClient {

    /**
     * 上传文件
     *
     * @param file         文件
     * @return 文件存储URL
     */
    @PostMapping(value = "/uploadFile", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    String uploadFile(@RequestPart("file") MultipartFile file);

    /**
     * 批量上传文件
     *
     * @param files        文件数组
     * @return 文件存储URL数组
     */
    @PostMapping(value = "/uploadFiles", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    Map<String, List<String>> uploadFiles(@RequestPart("files") MultipartFile[] files);
}