Question

My java code will not transfer my 25mb file – it will stop at 16mb. I have tried changing transferFrom 1 << 24 to 48 & 31 & 8 nothing helped just made it worse. Any idea?

ReadableByteChannel rbc = Channels.newChannel(fileURL.openStream());
FileOutputStream fos = new FileOutputStream(path + fileName);
fos.getChannel().transferFrom(rbc, 0, 1 << 24);
fos.close();

Answer 1

In case you use Java7 you can use the fancy java.nio.file.Files utils to copy.

 URL url = new URL("http://www.stackoverflow.com");
 try (InputStream is = url.openStream()) {
    Files.copy(is, Paths.get("/tmp/output.tmp"));
 }

In case you not, you can use the open source utils- e.g. from Apache (search for FileUtils in Commons IO).

And in case you want to stick arround with your current solution, you can write it like this:

BufferedInputStream bis = new BufferedInputStream(url.openStream());
BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(
    "/tmp/output2.tmp"));

byte[] buffer = new byte[1024 * 1024];
int read = 0;
while ((read = bis.read(buffer)) != -1) {
  bos.write(buffer, 0, read);
}
bos.close();
bis.close();

The intention is that you have to read until the end of the stream has been reached. That is why your transferFrom only downloads a limited amount of data as there is no guarantee that all the data will be transferred in one chunk.