Java中的客户端共享已下载的文件已损坏

Question

I tried to create the file on server side using the inputstream which I am getting from client side.

File is created with the same size as of original file. But when trying to open it is showing that file is corrupted.

fileSharing.jsp on client server which is trying to share file (Sender)

HttpURLConnection httpURLConnection = null;
OutputStream os = null;
InputStream is = null;
try {
    File fileObj = new File("D://test.pdf");
    out.print("File Length " + fileObj.length() + " Name " + fileObj.getName());
    URL url = new URL("http://localhost:2080/Receiver/fileupload?filename=test.pdf&filelength=" + fileObj.length());
    httpURLConnection = (HttpURLConnection) url.openConnection();
    httpURLConnection.setDoOutput(true);
    httpURLConnection.setRequestMethod("POST");
    httpURLConnection.setRequestProperty("Content-Type", "multipart/mixed");
    httpURLConnection.setRequestProperty("Connection", "Keep-Alive");
    httpURLConnection.setRequestProperty("Cache-Control", "no-cache");
    httpURLConnection.setRequestProperty("Content-Disposition", "form-data; name=\"Dummy File Description\"");
    httpURLConnection.setChunkedStreamingMode(8192);
    httpURLConnection.connect();

    is = new BufferedInputStream(new FileInputStream(fileObj));
    os = new BufferedOutputStream(httpURLConnection.getOutputStream());

    byte[] buff = new byte[8192];
    int len = 0;
    while ((len = is.read(buff, 0, buff.length)) > 0) {
        os.write(buff, 0, len);
        os.flush();
    }
} catch (Exception e) {
    e.printStackTrace();
} finally {
    is.close();
    os.close();
    httpURLConnection.disconnect();
}

FileUploadController servlet on server side which is trying to download the file (Receiver)

InputStream is = null;
OutputStream os = null;
try {
    is = request.getInputStream();
    int total = 0;
    int bytes = 0;
    os = new BufferedOutputStream(new FileOutputStream(new File("D://files//dummy.pdf")));
    byte[] buff = new byte[8192];
    while (true) {
        if ((bytes = is.read(new byte[8192])) == -1) {
            System.out.println("File shared successfully");
            System.out.println("Total " + total);
            break;
        }
        total = total + bytes;
        System.out.println("Length " + bytes);
        os.write(buff, 0, bytes);
        //os.flush();
    }
} catch (Exception e) {
    e.printStackTrace();
} finally {
    is.close();
    os.close();
}

Answer 1

In the reading loop of FileUploadController you instantiate a new array and read into it, but you don't hold on to it to continue using it:

 byte[] buff = new byte[8192];
 while(true){
     if((bytes = is.read(new byte[8192])) == -1){

Yet, you write buff to the file (which will be full of 0-bytes, so you'll have a file with the correct length, but it's full of 0 instead of the actual data).

Replace that last line with

     if((bytes = is.read(buff)) == -1){