SpringCloud---Feign上传下载详解

1.使用原因

公司最近做的项目在用SpringCloud，涉及到了上传。但是Feign本身是不支持文件类型的。所以这里把上传下载的实现分享一下。

2.所需配置

这是自己实现的一个formEncoder，可以支持单文件和数组的多文件上传

public class FeignSpringFormEncoder extends FormEncoder {

    /**
     * Constructor with the default Feign's encoder as a delegate.
     */
    public FeignSpringFormEncoder() {
        this(new 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)) {
            MultipartFile file = (MultipartFile) object;
            Map data = Collections.singletonMap(file.getName(), object);
            super.encode(data, MAP_STRING_WILDCARD, template);
            return;
        } else if (bodyType.equals(MultipartFile[].class)) {
            MultipartFile[] file = (MultipartFile[]) object;
            if(file != null) {
                Map data = Collections.singletonMap(file.length == 0 ? "" : file[0].getName(), object);
                super.encode(data, MAP_STRING_WILDCARD, template);
                return;
            }
        }
        super.encode(object, bodyType, template);
    }
}

将实现的类注册一下。

@Bean
public Encoder feignEncoder(ObjectFactory<HttpMessageConverters> messageConverters) {
    return new FeignSpringFormEncoder(new SpringEncoder(messageConverters));
}

调用方的代码，这里参数接收的时候用的是@RequestPart，与@RequestParam区别大家可以去查一下。

@PostMapping(value = "/upload", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
@ResponseBody
public ApiResult upload(@RequestPart(value = "file") MultipartFile file) {
    return fileUploadApiClient.upload(file);
}

暴露的fileUploadApiClient接口还需要添加依赖

<dependency>
    <groupId>io.github.openfeign.form</groupId>
    <artifactId>feign-form</artifactId>
    <version>3.3.0</version>
</dependency>
<dependency>
    <groupId>io.github.openfeign.form</groupId>
    <artifactId>feign-form-spring</artifactId>
    <version>3.3.0</version>
</dependency>

暴露的fileUploadApiClient代码，MediaType类型的指定

@PostMapping(value = "/oss/upload", consumes = MediaType.MULTIPART_FORM_DATA_VALUE, produces = MediaType.APPLICATION_JSON_VALUE)
ApiResult upload(@RequestPart(value = "file") MultipartFile file);

最后直接调用就可以上传成功.