问题
When make a post request from one microservice to another using feign client of spring cloud netflix, I get the following error in Postman :
{
"timestamp": 1506933777413,
"status": 500,
"error": "Internal Server Error",
"exception": "feign.codec.EncodeException",
"message": "Could not write JSON: No serializer found for class java.io.FileDescriptor and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS); nested exception is com.fasterxml.jackson.databind.JsonMappingException: No serializer found for class java.io.FileDescriptor and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile[\"inputStream\"]->java.io.FileInputStream[\"fd\"])",
"path": "/attachments"
}
And my eclipse console shows the following exception :
com.fasterxml.jackson.databind.JsonMappingException: No serializer found for class java.io.FileDescriptor and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile["inputStream"]->java.io.FileInputStream["fd"]) at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:284) ~[jackson-databind-2.8.9.jar:2.8.9] at com.fasterxml.jackson.databind.SerializerProvider.mappingException(SerializerProvider.java:1110) ~[jackson-databind-2.8.9.jar:2.8.9] at com.fasterxml.jackson.databind.SerializerProvider.reportMappingProblem(SerializerProvider.java:1135) ~[jackson-databind-2.8.9.jar:2.8.9] at com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.failForEmpty(UnknownSerializer.java:69) ~[jackson-databind-2.8.9.jar:2.8.9] at com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.serialize(UnknownSerializer.java:32) ~[jackson-databind-2.8.9.jar:2.8.9] at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:704) ~[jackson-databind-2.8.9.jar:2.8.9] at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:689) ~[jackson-databind-2.8.9.jar:2.8.9] at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155) ~[jackson-databind-2.8.9.jar:2.8.9] at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:704) ~[jackson-databind-2.8.9.jar:2.8.9] at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:689) ~[jackson-databind-2.8.9.jar:2.8.9] at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155) ~[jackson-databind-2.8.9.jar:2.8.9] at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:292) ~[jackson-databind-2.8.9.jar:2.8.9] at com.fasterxml.jackson.databind.ObjectWriter$Prefetch.serialize(ObjectWriter.java:1429) ~[jackson-databind-2.8.9.jar:2.8.9] at com.fasterxml.jackson.databind.ObjectWriter.writeValue(ObjectWriter.java:951) ~[jackson-databind-2.8.9.jar:2.8.9]
UPDATE 1
This is my feign interface :
@FeignClient(name="attachment-service", fallback=AttachmentHystrixFallback.class)
public interface AttachmentFeignClient {
@RequestMapping("upload")
void upload(@RequestPart(name="file") MultipartFile file, @RequestParam(name="attachableId") Long attachableId,
@RequestParam(name="className") String className, @RequestParam(name="appName") String appName);
And this is the main microservice controller :
@RestController
public class AttachmentController implements Serializable {
/**
*
*/
private static final long serialVersionUID = -4431842080646836475L;
@Autowired
AttachmentService attachmentService;
@RequestMapping(value = "attachments", method = RequestMethod.POST, consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
public void upload(@RequestPart MultipartFile file, @RequestParam Long attachableId, @RequestParam String className, @RequestParam String appName) throws Exception {
attachmentService.uploadFile(file, attachableId, className, appName);
}
}
I'm certainly missing some kind of serializer here
Any suggestion would be appreciated !
Thanks
回答1:
After few days searching a solution I found this. You should start to add feign form for spring dependency :
<dependency>
<groupId>io.github.openfeign.form</groupId>
<artifactId>feign-form-spring</artifactId>
<version>3.3.0</version>
</dependency
Then your feign client need this spring form encoder :
@FeignClient(name="attachment-service", configuration = {AttachmentFeignClient.MultipartSupportConfig.class}
fallback=AttachmentHystrixFallback.class)
public interface AttachmentFeignClient {
@RequestMapping(value= {"upload"}, consumes = {"multipart/form-data"})
void upload(@RequestPart(name="file") MultipartFile file, @RequestParam(name="attachableId") Long attachableId,
@RequestParam(name="className") String className, @RequestParam(name="appName") String appName);
public class MultipartSupportConfig {
@Bean
@Primary
@Scope("prototype")
public Encoder feignFormEncoder() {
return new SpringFormEncoder();
}
}
}
I hope it will help someone.
回答2:
TL;DR
Transform your MultiPartFile to MultiValueMap. See example below
The answer mentioned by @martin-choraine is the proper and the best answer to have your FeignClient method signature, the same as the actual endpoint signature that you are trying to call. However, there is a way around that does not require you to define a FormEncoder or add any extra dependency because in some applications you are not allowed to do that (enterprise shit); all what you need is to transform your MultipartFile to a MultiValueMap and it will perfectly work as the standard encoder will be able to serialize it.
Actual EndPoint to be called
@PostMapping(path = "/add", consumes = MULTIPART_FORM_DATA_VALUE, produces = APPLICATION_JSON_VALUE)
public MyResponseObject add(@RequestParam(name = "username") String username,
@RequestPart(name = "filetoupload") MultipartFile file) {
Do something
}
The POST method in your FeignClient should look like this
@PostMapping(path = "/myApi/add", consumes = MULTIPART_FORM_DATA_VALUE,
produces = APPLICATION_JSON_VALUE)
public MyResponseObject addFile(@RequestParam(name = "username") String username,
@RequestPart(name = "filetoupload") MultiValueMap<String, Object> file);
Then when you call the addFile you should provide MultiValueMap like this
public MyResponseObject addFileInAnotherEndPoint(String username, MultipartFile file) throws IOException {
MultiValueMap<String, Object> multiValueMap = new LinkedMultiValueMap<>();
ByteArrayResource contentsAsResource = new ByteArrayResource(file.getBytes()) {
@Override
public String getFilename() {
return file.getOriginalFilename();
}
};
multiValueMap.add("filetoupload", contentsAsResource);
multiValueMap.add("fileType", file.getContentType());
return this.myFeignClient.addFile(username, multiValueMap);
}
回答3:
i have added consumes = MediaType.MULTIPART_FORM_DATA_VALUE in the post and it works for me. this is my feign client method and in the front i worked with formdata
@PostMapping(path=Urls.UPLOAD_FILE_IN_LIBELLE, consumes = MediaType.MULTIPART_FORM_DATA_VALUE )
public void uploadFileInLibelle(
@RequestParam String processus,
@RequestParam String level0Name,
@RequestParam String nomFichier,
@RequestParam String nomLibelle,
@RequestParam String anneeFolderName,
@RequestParam String semaineFolderName,
@RequestPart MultipartFile fichier);
this is my angular frontent
public uploadFiles(
nomFichier: string,
nomLibelle: string,
processus: string,
level0Name: string,
semaineFolderName: string,
anneeFolderName: string,
byte: File
): Observable<any> {
const formData = new FormData();
formData.set('processus', processus);
formData.set('level0Name', level0Name);
formData.set('nomLibelle', nomLibelle);
formData.set('anneeFolderName', anneeFolderName);
formData.set('semaineFolderName', semaineFolderName);
formData.set('nomFichier', nomFichier);
formData.set('fichier', byte);
return this.httpClient.post(this.urlUploadFile, formData);
}
来源：https://stackoverflow.com/questions/46522304/file-upload-spring-cloud-feign-client