Spring Cloud feign 多文件上传

电玩女神 2022-05-16 00:34 354阅读 0赞

先说一下我的应用场景，第三方调用的我的接口，上传若干个文件，我用MultiPartFile\[\] 数组接收，之后我调用其他服务的接口，吧文件发送过去，统一保存。目前存在的问题就是，当你使用feign传递MultipartFile对象时，接收方无法解析，所以，需要重写feign的encoder，让它支持MultipartFile类型以及MultipartFile\[\]数组类型

首先加上两个jar包：

<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>

这里重写FormEncoder使得feign可以支持文件传输：

import feign.RequestTemplate;
    import feign.codec.EncodeException;
    import feign.codec.Encoder;
    import feign.form.ContentType;
    import feign.form.FormEncoder;
    import feign.form.MultipartFormContentProcessor;
    import feign.form.spring.SpringManyMultipartFilesWriter;
    import feign.form.spring.SpringSingleMultipartFileWriter;
    import org.springframework.web.multipart.MultipartFile;
    
    import java.lang.reflect.Type;
    import java.util.Collections;
    import java.util.Map;
    
    
    /**
     * @version: 1.00.00
     * @description:
     * @copyright:
     * @company: 
     * @author: panfan
     * @date: 2018/8/13 17:27
     * @history:
     */
    public class SpringMultipartEncoder extends FormEncoder {
    
        /**
         * Constructor with the default Feign's encoder as a delegate.
         */
        public SpringMultipartEncoder() {
            this(new Default());
        }
    
    
        /**
         * Constructor with specified delegate encoder.
         * @param delegate delegate encoder, if this encoder couldn't encode object.
         */
        public SpringMultipartEncoder(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 {
            // 单MultipartFile判断
            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数组处理
                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;
                }
            }
            // 其他类型调用父类默认处理方法
            super.encode(object, bodyType, template);
        }
    
    
    }

下面做配置，为Encoder注入messageConverters：

@Configuration
    public class FeignMultipartSupportConfig {
    
    
    //    @Bean
    //    public Encoder feignEncoder(ObjectFactory<HttpMessageConverters> messageConverters) {
    //        return new SpringMultipartEncoder(new SpringEncoder(messageConverters));
    //    }
    
        @Autowired  
        private ObjectFactory<HttpMessageConverters> messageConverters;  
    
        @Bean
        public Encoder feignEncoder() {
            return new SpringMultipartEncoder(new SpringEncoder(messageConverters));
        }
    
    
    }

我的文件上传接口如下，接受到文件，调用fileSystemService传输到文件处理组件：

@RequestMapping(value = "/file/upload")
        @ResponseBody
        public ResourceUploadResponse uploadPicture(@RequestParam("access_token") String accessToken, HttpServletRequest request,
                                    @RequestParam("files") MultipartFile[] files, HttpServletResponse response,
                                    @RequestParam("file_type") int fileType) {
    
    
    
    /**  中间代码略 **/
    
     // 上传图片，fileSystemService 是fastdfs文件操作的统一微服务。
            ResourceUploadResponse resultFeign = fileSystemService.saveImg(files, fileType);
            if(resultFeign.getCode() == 1){
                return new ResourceUploadResponse(Constant.RESPONSE_STATE_SUCCESS, Constant.RESPONSE_CODE_SUCCESS, "上传照片成功", resultFeign.getUrls());
            }else{
                return new ResourceUploadResponse(Constant.RESPONSE_STATE_FAIL, Constant.RESPONSE_CODE_FAIL, "接口调用失败", null);
            }
    
    }

我的feignclient:

@FeignClient(value = "file-system", fallbackFactory = FileSystemServiceHystrix.class, configuration = SpringMultipartEncoder.class
    (这里是SpringMultipartEncoder.class还是FeignMultipartSupportConfig.class需要你们试一试，评论说是后者，我的博客一开始写的是前者，两个都试试吧，之前的代码已不见了))
    public interface FileSystemService {
    
    
        // 存储图片，返回所有图片在fastdfs上的urls
        @RequestMapping(method = RequestMethod.POST, value = "/rest/fs/resource/common/multiFileUpload",
                consumes = MediaType.MULTIPART_FORM_DATA_VALUE, produces = MediaType.APPLICATION_JSON_VALUE)
        ResourceUploadResponse saveImg(@RequestPart(value = "files") MultipartFile[] files, @RequestParam(value = "bizType") int bizType);
    
    
    }

### 上面有个SpringMultipartEncoder，不要慌这个是我们重写刚才导入jar包中的FormEncoder(代码在下面)，以让他支持任意数量文件上传，同时，这里用@RequestPart ，注意不能用@RequestParam，如果用@RequestParam，被调用的服务方会出现如下错误： ###

Caused by: org.apache.commons.fileupload.FileUploadException: the request was rejected because no multipart boundary was found

关于@RequestPart和@RequestParam的区别，我们看@RequestPart的注释，

![70][]

好，这里说了，

他们最大的不同是，当请求方法的请求参数类型不再是String类型的时候，@RequestParam依赖于注册Converter或者PropertyEditor来解析参数，而 @RequestPart则是通过HttpMessageConverter来根据Content-Type决定采用的消息转换器。  
总之，@RequestParam适用于name-valueString类型的请求域，@RequestPart适用于复杂的请求域（像JSON，XML）。

最后，我们的文件操作统一组件接口代码，也就是服务被调用方接受multipartfile的Controller方法，如下处理：

@PostMapping("/common/multiFileUpload")
        public ResourceUploadResponse multiFileUpload(@RequestParam("files") MultipartFile[] files, int bizType){
            
            // 略略略~~~
            return "上传成功";
        }

完美！！！

[70]: /images/20220516/7d8c6af64e3246008a6ad3cd53780fb7.png