Reading/Writing Multiple Files From/To Socket

Question

I'm have a problem in recognizing end of file in socket.
when I write files one after another using object input stream wrapped on the socket's input stream.
on one side:
while((n = send_file_input_stream[ i ].read(buff)!=-1)
socket_output_stream.write(buff,0,n)
on the other side:
while((n = socket_input_stream.read(buff)!=-1)
recv_file_output_stream[ i ].write(buff,0,n)
this process happens for i=1..N files
1) how can i signal the socket That EOF occures ?
2) how can the recieving socket stream recognize it?
3) Is there a simple mechnism for transffering files in java
from dir to dir from disk to socket ?
like copy(InputStream from,OutputStram to)
Thanks
Joseph

Answer 1

one way is to write something as an end of file marker after each file, say character 255, just make sure you escape any 255's in the file (say by sending two 255's)
The other end then needs to look for the 255's, if it gets one on its own its the end of the file. If it get's two together its a single 255 thats part of the file.
If that seems a bit complicated you could send a header with the count of bytes before each file, the receiving end then just has to count bytes.
Another way is to use a new connection for each file (probably also the easiest)