How to send list of files by RESTEasy java

Question

How can we send list of files by RESTEasy java client? Spring REST is:

@PostMapping()
public ResponseEntity<?> send(@RequestPart(value = "message") String message, @RequestPart(value = "attachment", required = false) List<MultipartFile> attachments)

In Postman it is made by specifying multiple files in form-data with one key "attachment", but MultipartFormDataOutput has Map inside, so it remembers only the last added file.

Answer 1

I have resolved this problem with using org.apache.http.entity.mime.MultipartEntityBuilder:

MultipartEntityBuilder builder = MultipartEntityBuilder.create();
builder.addTextBody("message", messageStr, ContentType.TEXT_PLAIN.withCharset(UTF_8));
for (File file: files) {
    builder.addBinaryBody(
            "attachment",
            new FileInputStream(file),
            ContentType.APPLICATION_OCTET_STREAM,
            file.getName()
    );
}
CloseableHttpClient httpClient = HttpClients.createDefault();
HttpPost uploadFile = new HttpPost(url);
uploadFile.setEntity(builder.build());
CloseableHttpResponse response = httpClient.execute(uploadFile);