Question

I am having a problems trying to send a file from a server program to a client program over a socket. SO fair I have tried splitting it into bytes but I haven’t had any success so far. Also the server must be concurrent so I am unsure where I should put the code to send the file.

Thanks

EDIT:

Here is the code that I have tried so far, at the moment It transfers a copy of the file into where its meant to be but the file size is zero bytes 🙁

In the Protocol class :

try {
    File program = new File("./src/V2AssignmentCS/myProgram.jar");

byte[] mybytearray = new byte[4096];

FileInputStream fis = new FileInputStream(program);

BufferedInputStream bis = new BufferedInputStream(fis);

bis.read(mybytearray, 0, mybytearray.length);

OutputStream os = sock.getOutputStream();

System.out.println("Sending...");

os.write(mybytearray, 0, mybytearray.length);

os.flush();

} catch (IOException e) {

        System.err.println("Input Output Error: " + e);

    }

And on the client side :

long start = System.currentTimeMillis();
int bytesRead;
int current = 0;
// localhost for testing

// receive file
byte [] mybytearray  = new byte [ServerResponse.programSize()];
InputStream is = sock.getInputStream();
FileOutputStream fos = new FileOutputStream("./src/V2AssignmentCS/newProgram.jar");
BufferedOutputStream bos = new BufferedOutputStream(fos);
bytesRead = is.read(mybytearray,0,mybytearray.length);
current = bytesRead;

// thanks to A. Cádiz for the bug fix
do {
   bytesRead =
      is.read(mybytearray, current, (mybytearray.length-current));
   if(bytesRead >= 0) current += bytesRead;
} while(bytesRead > -1);

bos.write(mybytearray, 0 , current);
bos.flush();
long end = System.currentTimeMillis();
System.out.println(end-start);
bos.close();
sock.close();

Answer 1

bis.read(mybytearray, 0, mybytearray.length);

You are ignoring the result code returned by this method. Check the Javadoc. It isn’t what you clearly expect it to be.

os.write(mybytearray, 0, mybytearray.length);

Here you are writing exactly 4096 bytes. Was that your intention?

bytesRead = is.read(mybytearray,0,mybytearray.length);
current = bytesRead;
// thanks to A. Cádiz for the bug fix
do {
   bytesRead =
      is.read(mybytearray, current, (mybytearray.length-current));
   if(bytesRead >= 0) current += bytesRead;
} while(bytesRead > -1);

The canonical way to copy streams in Java, which you should be using at both ends, is as follows:

int count;
byte[] buffer = new byte[8192]; // or whatever you like
while ((count = in.read(buffer)) > 0)
{
  out.write(buffer, 0, count);
}
out.close();
in.close();