Android将文件大块上传到PHP

Question

How can we upload big files in chunks to a PHP server so that if the connection dies, the upload can be resumed at any time.

Specifically, what libraries are needed in Android to do this?

The users are uploading big files from countries with slow/unstable internet connections. Thank you

EDIT

More info, I'm currently using HTTP POST to upload the whole file at once. As the following code shows:

private int uploadFiles(File file) {
        String zipName = file.getAbsolutePath() + ".zip";
        if(!zipFiles(file.listFiles(), zipName)){
            //return -1;
            publishResults(-1);
        }
        //publishProgress(-1, 100);
        HttpURLConnection connection = null;
        DataOutputStream outputStream = null;
        DataInputStream inputStream = null;

        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
        String serverUrl = prefs.getString("serverUrl", "ServerGoesHere"); // todo ensure that a valid string is always stored
        String lineEnd = "\r\n";
        String twoHyphens = "--";
        String boundary = "*****";
        int bytesRead, bytesAvailable, bufferSize;
        byte[] buffer;
        int maxBufferSize = 1 * 1024 * 1024;
        int responseCode = -1;
        try {
            //notif title, undeterministic
            pNotif.setContentText("Zipping complete. Now Uploading...")
                  .setProgress(0, 0, true);
            mNotifyManager.notify(NOTIFICATION_ID, pNotif.build()); // make undeterministic

            //update progress bar to indeterminate
            sendUpdate(0, 0, "Uploading file."); // sendupdate using intent extras

            File uploadFile = new File(zipName);
            long totalBytes = uploadFile.length();
            FileInputStream fileInputStream = new FileInputStream(uploadFile);

            URL url = new URL(serverUrl);
            connection = (HttpURLConnection) url.openConnection();

            connection.setDoInput(true);
            connection.setDoOutput(true);
            connection.setUseCaches(false);

            connection.setRequestMethod("POST");

            connection.setRequestProperty("Connection", "Keep-Alive");
            connection.setRequestProperty("Content-Type",
                    "multipart/form-data;boundary=" + boundary);
            outputStream = new DataOutputStream(connection.getOutputStream());
            outputStream.writeBytes(twoHyphens + boundary + lineEnd);
            outputStream
            .writeBytes("Content-Disposition: form-data; name=\"uploadedfile\";filename=\""
                    + zipName + "\"" + lineEnd);
            outputStream.writeBytes(lineEnd);

            bytesAvailable = fileInputStream.available();
            bufferSize = Math.min(bytesAvailable, maxBufferSize);
            buffer = new byte[bufferSize];
            long bytesUploaded = 0;
            bytesRead = fileInputStream.read(buffer, 0, bufferSize);

            while (bytesRead > 0) {
                bytesUploaded += bytesRead;
                outputStream.write(buffer, 0, bufferSize);
                bytesAvailable = fileInputStream.available();
                bufferSize = Math.min(bytesAvailable, maxBufferSize);
                bytesRead = fileInputStream.read(buffer, 0, bufferSize);
                //int percentCompleted = (int) ((100 * bytesUploaded) / totalBytes);
                //publishProgress((int)bytesUploaded/1024, (int)totalBytes/1024);

                System.out.println("bytesRead> " + bytesRead);
            }

            //publishProgress(-2, 1); // switch to clean up
            outputStream.writeBytes(lineEnd);
            outputStream.writeBytes(twoHyphens + boundary + twoHyphens
                    + lineEnd);
            try {
                responseCode = connection.getResponseCode();
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            fileInputStream.close();
            outputStream.flush();
            outputStream.close();
            // Delete the zip file
            new File(zipName).delete();
        } catch (Exception ex) {
            new File(zipName).delete();
            responseCode = -1;
            ex.printStackTrace();
        } 
        return responseCode;
    }

Is there a way to modify this to send it by chunks? Most of the research I've done has not been very clear, sorry

Answer 1

It is not a good idea to upload a file in chunks via HTTP, since it is a stateless protocol and you would need to make a new connection for every chunk you want to send to the server. Furthermore, you have to maintain state between this transfers manually and there is no assurance that the files will arrive in the order they are sent.

You should use socket programming with TCP sockets which maintain a connection until the whole file is send. You can then push chunks into the socket and they will arrive without loss and in the same order they are fed to the socket.

Answer 2

I ended up implementing resumable uploads using an SFTP library. JSch http://www.jcraft.com/jsch/ I upload using SFTP and the library handles the resumable mode. Example code:

JSch jsch = new JSch();
session = jsch.getSession(FTPS_USER,FTPS_HOST,FTPS_PORT);
session.setPassword(FTPS_PASS);
java.util.Properties config = new java.util.Properties();
config.put("StrictHostKeyChecking", "no");
session.setConfig(config);
session.connect();
channel = session.openChannel("sftp");
channel.connect();
channelSftp = (ChannelSftp)channel;
channelSftp.cd(FTPS_PATH);

File uploadFile = new File(zipName); // File to upload
totalSize = uploadFile.length(); // size of file

// If part of the file has been uploaded, it saves the number of bytes. Else 0
try {
    totalTransfer = channelSftp.lstat(uploadFile.getName()).getSize();
} catch (Exception e) {
    totalTransfer = 0;
}

// Upload File with the resumable attribute
channelSftp.put(new FileInputStream(uploadFile), uploadFile.getName(), new SystemOutProgressMonitor(), ChannelSftp.RESUME);

channelSftp.exit();
session.disconnect();

With this library I fulfilled all the requirements: resumable uploads and upload progress.