android : faster solution to copying one file to another

Question

I am copying files using BufferedInputStream . I copy byte[] in loop. This is quite slow for big files.

I saw the FileChannel structure. I tried using this also. I want to know if FileChannel is better than using IOSTreams. During my testings, i am not able to see a major performance improvement.

Or is there any other better solution.

My requirement is modify first 1000 bytes of src file and copy to target, copy the rest of the byte of the src file to target file.

With fileChannel

private  void copyFile(File sourceFile, File destFile,byte[] buffer,int srcOffset, int destOffset) {
    try {
        if (!sourceFile.exists()) {
            return;
        }
        if (!destFile.exists()) {
            destFile.createNewFile();
        }
        FileChannel source = null;
        FileChannel destination = null;
        source = new FileInputStream(sourceFile).getChannel();
        source.position(srcOffset);
        destination = new FileOutputStream(destFile).getChannel();
        destination.write(ByteBuffer.wrap(buffer));
        if (destination != null && source != null) {
            destination.transferFrom(source, destOffset, source.size()-srcOffset);
        }
        if (source != null) {
            source.close();
        }
        if (destination != null) {
            destination.close();
        }

    } catch (Exception ex) {
        ex.printStackTrace();
    }
}

using I/O stream

while ((count = random.read(bufferData)) != -1) {

            fos.write(bufferData, 0, count);
        }

Answer 1

I believe that performance cannot be noticeably increased since hard disk/sd-card speed is probably the bottleneck.

However it might help to create a background task that does the copying.

This is not realy faster but it feels faster because you donot have to wait for the completion of the copy operation.

This solution only works if your app does not need the result immediately after starting.

For details see AsyncTask

Answer 2

transferFrom() must be called in a loop. It isnt' guaranteed to transfer the entire amount in a single call.

Answer 3

I have finally did it using overwrite and renaming. Used Randomfile to overwrite first x bytes. Then renamed the file. Now it is much faster and takes the same time for all files regardless of their size.

Thanks.