Sending files by part in JAVA

Question

I am writing a client-server program in JAVA in which I am sending a file from server to client.As the file size may be quite high therefore I decided to divide the file in 5 parts and then send it to the same client in 5 different Threads.

• My Algorithm is to use Java Zip API and create a zip file of the file to be sent,then I will divide the Zip file into 5 parts. The problem is that there is not method in [ZIP API][2] that could divide the file. This is the tutorial that I am referring for sending files through Thread. Anyone who can guide me is there anything wrong with my Algorithm Or do I have to do with different strategy?

Answer 1

You should separate the zipping part from the splitting part. If you have to send these to a client, you probably don't want to keep the complete zip file in memory while you wait for the client to request the next chunk... so the simplest approach would be to zip to disk first, and then serve that file in chunks. At that point, it really doesn't matter that it's a zip file at all - and indeed for certain files types (e.g. images, sound, video) you may not want to go via a zip file at all.

I would suggest you tell the client the file name and size, and then let the client request whatever section of the file it wants. It can then decide what chunk size to use: you just need to seek to the right bit of the file and serve as much data as the client has requested.

Answer 2

Breaking up the file isn't a ZIP function. You could create multiple byte arrays from the resulting zip file (by segmenting the array) and sending each segment in a different thread. This would be similar to what download managers of yesteryear would do.

The client would then have code to re-assemble the byte array in the correct order. You'd probably need to add some additional information to each segment like the correct sequence, the filename to be restored, and the number of segments expected.