使用FeignClient上传文件

问题

使用FeignClient上传文件时居然失败了?意外,不敢相信SpringCloud中的组件不可能不支持该功能
版本
SpringCloud: Dalston.Release
feign: 9.4.0

期间有各种报错,如:
FileUploadException: the request was rejected because no multipart boundary was found
MissingServletRequestPartException: Required request part ‘file’ is not present

原因

因为feign 9.4.0默认并不支持multipart/form(文件上传),需要手动引入feign-form、feign-form-spring

使用方式

引入feign-form依赖

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<dependencies>
<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>
</dependencies>

改造上传文件FeignClient

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@FeignClient(
name = "file-upload-service",
configuration = FileUploadServiceClient.MultipartSupportConfig.class
)
public interface FileUploadServiceClient extends IFileUploadServiceClient {

public class MultipartSupportConfig {

@Autowired
private ObjectFactory<HttpMessageConverters> messageConverters;

@Bean
public Encoder feignFormEncoder () {
// 支持文件上传FormEncoder及之前默认的其它Encoder
return new SpringFormEncoder(new SpringEncoder(messageConverters));
}
}
}

到此已可用

不同版本选择

上文中采用的feign-form版本是与feign版本是对应的。如果版本对应错误,是不兼容的。

spring-cloud feign feign-form
Dalston 9.4.0 3.5.0以前(20191122最新:3.4.1)
Greenwich 10.4.0 3.5.0以后(20191122最新:3.8.0)

MultipartFile接收时找不到问题

MissingServletRequestPartException: Required request part ‘file’ is not present
正常情况下可能是指定的文件名不对,其它的可能不谈,只谈我在使用过程中遇到问题
用户端: 上传文件
Server1: 接收用户上传文件
Server2: 接收服务器端1上传文件
1、Server2代码示例

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@RequestMapping(value = "upload", method = RequestMethod.POST,
consumes = {MediaType.MULTIPART_FORM_DATA_VALUE})
@ResponseBody
public void checkin(@RequestPart("file") MultipartFile file) {
// do something
}

2、Server1代码示例

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@RequestMapping(value = "upload", method = RequestMethod.POST,
consumes = {MediaType.MULTIPART_FORM_DATA_VALUE})
@ResponseBody
public RespBody checkin(@RequestPart("file1") MultipartFile file1) {
Server2FeignClient.upload(file1);
return RespBody.ok();
}

Server2FeignClient关键代码

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void upload(@RequestPart("file") MultipartFile file);

结果就是Server2可以接收到请求,但是收不到file文件,此时我们查看Server1中的MultipartFile对象发现,虽然已经在Server2FeignClient中设置MultipartFile 的key为file,但是Server2收到的仍然是file1。

解决方法: 通过反映方式将MultipartFile的fieldName改为Server2需要的key

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Field partField = multipartFile.getClass().getDeclaredField("part");
partField.setAccessible(true);
ApplicationPart part = (ApplicationPart) partField.get(multipartFile);
Field fileItemField = part.getClass().getDeclaredField("fileItem");
fileItemField.setAccessible(true);
org.apache.tomcat.util.http.fileupload.disk.DiskFileItem fileItem = (org.apache.tomcat.util.http.fileupload.disk.DiskFileItem) fileItemField.get(part);
fileItem.setFieldName("file");
引用

https://github.com/OpenFeign/feign-form

转载请标明出处:
http://blog.520wa.com/2019/11/22/feign-upload-file/
本文出自Tu’s blog