在Discord Bot上上传用户文件

Question

I'm trying to have users submit files on discord that are then uploaded to a site for processing. However, there seem to be something wrong wiht my code.

When i upload a file i get respone code 400 (bad request) but the site should accept files of w3g format.

private static void onFileUpload(Message.Attachment attachment, TextChannel channel) {
    // api.wc3stats.com/upload
    String fileName = attachment.getFileName();
    if (fileName.substring(fileName.length() - 3).equals("w3g")) {

        File file = new File(attachment.getFileName());
        attachment.downloadToFile(file);
        try {
            HttpHelper.postFile(file, "https://api.wc3stats.com/upload");
            channel.sendMessage("Uploading: " + file.toString()).queue();
        } catch (IOException e) {
            e.printStackTrace();
            channel.sendMessage(e.getMessage()).queue();
        }
        System.out.println("Deleted");
        file.delete();

    } else {
        channel.sendMessage("Invalid file type.").queue();
    }
}

public static void postFile(File file, String url) throws IOException {
    HttpURLConnection connection = null;
    FileInputStream fis = null;
    BufferedInputStream bis = null;
    BufferedOutputStream out = null;
    try {
        URL urlForPostRequest = new URL(url);
        connection = (HttpURLConnection) urlForPostRequest.openConnection();
        connection.setRequestMethod("POST");
        connection.setDoOutput(true);


        //if (responseCode == HttpURLConnection.HTTP_OK) {
            fis = new FileInputStream(file);
            bis = new BufferedInputStream(fis);
            out = new BufferedOutputStream(connection.getOutputStream());
            byte[] buffer = new byte[8192];
            int i;
            while ((i = bis.read(buffer)) > 0) {
                out.write(buffer, 0, i);
            }
       //}
        int responseCode = connection.getResponseCode();
        System.out.println("Response: " + connection.getResponseMessage());
        System.out.println(responseCode);
    } finally {
        if (fis != null) fis.close();
        if (bis != null) bis.close();
        if (out != null) out.close();
        System.out.println("closed");
    }
}

The current exception it's throwing me is that the file cannot be found. But I can clearly see it in the program directory after it's been attached to discord and downloaded. This also only happens the first time I upload the file. The second time i upload the same file it just gives me the bad request response.

First upload attempt LastReplay.w3g output:

    java.io.FileNotFoundException: lol.w3g 
    C:\SomePath\lol.w3g
    cannot be read
    closed
    Deleted

I can also note that the file now exists in the program directory. Though it should've been removed after everything is complete.

Second upload attempt of LastReplay.w3g output

C:\SomePath\lol.w3g
Can be read
Response: Bad Request
closed
Deleted

Answer 1

I managed to do it using Javascript with help using request-promise, as for java i did not...

        if (msg.attachments.size > 0) {
            let attached = msg.attachments.array()[0];
            const request = require('request-promise');
            let formData = {
                file: request (attached.url)
            };
            request.post('https://api.wc3stats.com/upload', {formData, json: true})
            .then(function (json) {
                // on success handle response json
            })
            .catch(function (err) {
                console.log(err);
            });
        }