spring cloud feign support file upload

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phenomenon

Spring Cloud Feign component not support file upload between micron service.
it may throw exception like this:

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feign.codec.EncodeException: class [Lorg.springframework.web.multipart.MultipartFile; is not a type supported by this encoder.
    at feign.codec.Encoder$Default.encode(Encoder.java:90) ~[feign-core-9.5.1.jar:na]
    at feign.form.FormEncoder.encode(FormEncoder.java:87) ~[feign-form-3.3.0.jar:3.3.0]
    at feign.form.spring.SpringFormEncoder.encode(SpringFormEncoder.java:64) ~[feign-form-spring-3.3.0.jar:3.3.0]

add dependencies

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<dependency>
    <groupId>io.github.openfeign.form</groupId>
    <artifactId>feign-form-spring</artifactId>
    <version>3.3.0</version>
</dependency>
<dependency>
    <groupId>io.github.openfeign.form</groupId>
    <artifactId>feign-form</artifactId>
    <version>3.3.0</version>
</dependency>
<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.3.3</version>
</dependency>

https://mvnrepository.com/artifact/io.github.openfeign.form/feign-form-spring

be careful the feign-form-spring depend on spring-web it may have conflict with your project.
for example in spring-boot:2.0.5.RELEASE spring-cloud:Finchley.SR1 project has already import
spring-web:5.0.9.RELEASE, if import feign-form-spring:3.3.0 it will import spring-web:4.3.18.RELEASE too,
it cause spring bean creation exception.

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<dependency>
    <groupId>io.github.openfeign.form</groupId>
    <artifactId>feign-form-spring</artifactId>
    <version>3.3.0</version>
    <exclusions>
        <exclusion>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
        </exclusion>
    </exclusions>
</dependency>

file receive part

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@ApiOperation("file upload receive part")
@RequestMapping(value = "/upload", method = RequestMethod.POST, consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
public List<XXX> uploadFile(
        @RequestPart(value = "files")
                MultipartFile[] files,
        @RequestParam(name = "userId")
        @ApiParam(name = "userId", value = "用户ID", required = true)
        @NotNull(message = "用户ID不能为空")
                Long userId,
        @RequestParam(name = "userName")
        @ApiParam(name = "userName", value = "用户名称", required = true)
        @NotBlank(message = "用户名不能为空")
                String userName){
                ...
}

be careful consumes property must add to the annotation RequestMapping
method property must be POST, RequestPart is working.

feign client part

client part is a little complex.

add configuration class:

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@Configuration
public class MultipartSupportConfig {

    @Autowired
    private ObjectFactory<HttpMessageConverters> messageConverters;

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

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

}
  • SpringFormEncoder support single file upload.
  • FeignSpringFormEncoder support file array upload.
  • SpringEncoder avoid project make RequestBody encoding error.

add form encoder

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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);
    }
}

add interface:

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@FeignClient(name = "upload-example", configuration = MultipartSupportConfig.class)
public interface CloudUploadService {

    @ApiOperation("文件上传")
    @RequestMapping(value = "/upload", method = RequestMethod.POST, consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    List<XXX> uploadFile(
            @RequestPart(value = "files")
                    MultipartFile[] files,
            @RequestParam(name = "userId")
            @ApiParam(name = "userId", value = "用户ID", required = true)
            @NotNull(message = "用户ID不能为空")
                    Long userId,
            @RequestParam(name = "userName")
            @ApiParam(name = "userName", value = "用户名称", required = true)
            @NotBlank(message = "用户名不能为空")
                    String userName);

}

in annotation FeignClient add configuration property, point to the encoding support class.

Testing

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@Slf4j
@RunWith(SpringJUnit4ClassRunner.class)
@SpringBootTest
public class UploadTester {

    @Autowired
    private CloudUploadService uploadService;

    @Test
    @SneakyThrows
    public void testHandleFileUpload() {

        File file = new File("upload.txt");
        DiskFileItem fileItem = (DiskFileItem) new DiskFileItemFactory().createItem("file",
                MediaType.TEXT_PLAIN_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 multi = new CommonsMultipartFile(fileItem);

        log.info(uploadService.handleFileUpload(new MultipartFile[]{multi}, 1L, "tester"));
    }

}

https://github.com/OpenFeign/feign-form
https://www.jianshu.com/p/4f4d9d084b1d
http://blog.didispace.com/spring-cloud-starter-dalston-2-4/
https://blog.csdn.net/gududedabai/article/details/79895893