File uploads generally use a request body in multipart/form-data format. The code to handle uploading files in Spring Boot is as follows:
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@PostMapping(path = "/upload", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
public void upload(@RequestParam("file1") MultipartFile file1,
@RequestParam("file2") MultipartFile file2) throws IOException, ServletException {
// Processing of uploaded files...
}
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The code above the upload method declares 2 parameters (including the form name of the file), representing 2 files. If we don’t know how many files are uploaded and the name of the file form. Then how to get all the uploaded files?
Servlet 3.0 provides a new Part interface which describes each uploaded file in the multipart/form-data request.
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@PostMapping(path = "/upload", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
public void upload(HttpServletRequest request) throws IOException, ServletException {
// Each file in a Multipart request
Collection<Part> parts = request.getParts();
for (Part part : parts) {
// Type of file
String contentType = part.getContentType();
// Form Name
String name = part.getName();
// Original file name
String fileName = part.getSubmittedFileName();
// File Size
long size = part.getSize();
log.info("contentType={}, name={}, fileName={}, size={}", contentType, name, fileName, size);
// Read file contents
try(InputStream inputStream = part.getInputStream()){
}
// It is also possible to write directly to the specified file.
// part.write(String fileName);
// Some other methods about header.
// part.getHeader(String name);
// part.getHeaderNames();
// part.getHeaders(String name);
}
}
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Note that the contents of a file can only be read once. part.getInputStream() and part.write(String fileName) can only execute one of these methods.
Reference https://springboot.io/t/topic/4853