[英]Empty List<MultipartFile> when trying to upload many files in Spring with ng-file-upload
I have the following controller method for uploading multiple files at once, inspired by this blog post and answers to this question as well:我有以下控制器方法可以一次上传多个文件,灵感来自这篇博客文章和这个问题的答案:
@RequestMapping(value = "/{user}/attachment", method = RequestMethod.POST)
@PreAuthorize(...)
public void upload(@PathVariable User user,
@RequestParam("file") List<MultipartFile> files) {
// handle files
}
However, the list of the files is always empty although request contains them.但是,尽管请求包含文件,但文件列表始终为空。
If I add the third MultipartRequest
parameter to the method:如果我将第三个
MultipartRequest
参数添加到方法中:
public void upload(@PathVariable User user,
@RequestParam("file") List<MultipartFile> files,
MultipartRequest request)
I can see it contains my uploaded files correctly:我可以看到它正确包含我上传的文件:
What might be the reason of empty List<MultipartFile>
?空
List<MultipartFile>
的原因可能是什么?
I'm using ng-file-upload to submit the files, but I don't think it is connected with the issue.我正在使用ng-file-upload提交文件,但我认为它与问题无关。 Spring 4.2.4.
春天 4.2.4。
The problem was that ng-file-upload by default submits array of files using names file[0]
, file[1]
etc. It is configurable with the arrayKey
value when using Upload
Service.问题是ng-file-upload默认使用名称
file[0]
、 file[1]
等提交文件数组。使用Upload
服务时,它可以使用arrayKey
值进行配置。 Setting it to empty string forces the files to be sent under the same file
key, which is correctly resolved with Spring and the @RequestParam("file") List<MultipartFile>
contains all files that has been submitted.将其设置为空字符串会强制文件在相同的
file
键下发送,Spring 正确解析了这一点,@ @RequestParam("file") List<MultipartFile>
包含已提交的所有文件。
Upload.upload({url: url, data: {file: arrayOfFiles}, arrayKey: ''})
Try to use @ModelAttribute
like this:尝试像这样使用
@ModelAttribute
:
@RequestMapping(value = "/{user}/attachment", method = RequestMethod.POST)
@PreAuthorize(...)
public void upload(@PathVariable User user,@ModelAttribute("uploadFile") FileUpload uploadFile) throws IllegalStateException, IOException {
List<MultipartFile> files = uploadFile.getFiles();
...
And create a class like:并创建一个类,如:
public class FileUpload {
private List<MultipartFile> files;
public List<MultipartFile> getFiles() {
return files;
}
public void setFiles(List<MultipartFile> files) {
this.files= files;
}
}
That works for me, sending big 'email' object with multiple file attachments from UI to back-end:这对我有用,将带有多个文件附件的大“电子邮件”对象从 UI 发送到后端:
Angular角
sendEmailWithAttachments(taskId: string, template: string, email: any, modelConfig: any, files: any[]) {
let formData = new FormData();
formData.append('form', new Blob([JSON.stringify(email)], {type: 'application/json'}));
files.forEach(file => {
formData.append('files', file);
});
return this.$http({
method: 'POST',
data: formData,
url: this.baseUrl + '/' + taskId + '/email-with-attachment?template=' + template,
headers: {
'Content-Type': undefined
},
responseType: 'arraybuffer'
});
}
Java Spring Java 春天
@RequestMapping(value = "{taskId}/email-with-attachment", method = RequestMethod.POST, consumes = MULTIPART_FORM_DATA_VALUE)
public void sendEmailWithAttachment(
@PathVariable String taskId,
@RequestParam String template,
@RequestParam("form") MultipartFile form,
@RequestParam("files") List<MultipartFile> files) throws IOException {
Map<String, String> parameters = new ObjectMapper().readValue(form.getInputStream(), HashMap.class);
System.out.println("taskId"+ taskId);
System.out.println("template"+ template);
System.out.println("files"+ files);
System.out.println("parameters"+ parameters);
}
for multiple files.对于多个文件。 do this in your javascript
在您的 javascript 中执行此操作
//first add files to form data
var formData = new FormData();
for (let i = 0; i < files.length; i++) {
formData.append("images", files[i]);
}
//post files to backend e.g using angular
$http.post('upload', formData, {
transformRequest: angular.identity,
headers: {'Content-Type': undefined}
})
.then(function(response){
console.log("UPLOAD COMPLETE::=> ", response);
}, function (error) {
console.log(error);
});
Do this in your java在你的java中做这个
//your java method signature
@PostMapping(value = "/upload", consumes = MediaType.MULTIPART_FORM_DATA_VALUE )
public Response uploadImage(RequestParam(value = "images") MultipartFile[] images){
}
I think that in the way you sent data from front, it can not bound with java.util.List.我认为在您从前面发送数据的方式中,它不能与 java.util.List绑定。 If you create a JSON data as request and you annotated your List with @RequestBody like:
如果您创建一个 JSON 数据作为请求并使用 @RequestBody 注释您的列表,例如:
@RequestMapping(value = "/{user}/attachment", method = RequestMethod.POST)
@PreAuthorize(...)
public void upload(@PathVariable User user,
@RequestBody List<MultipartFile> files) {
// handle files
}
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