Question

Server side code

public static boolean sendFile() {
        int start = Integer.parseInt(startAndEnd[0]) - 1;
        int end = Integer.parseInt(startAndEnd[1]) - 1;
        int size = (end - start) + 1;

        try {
            bos = new BufferedOutputStream(initSocket.getOutputStream());
            bos.write(byteArr,start,size);
            bos.flush();
            bos.close();
            initSocket.close();
            System.out.println("Send file to : " + initSocket);
        } catch (IOException e) {
            System.out.println(e.getLocalizedMessage());
            disconnected();
            return false;
        }

        return true;
    }

Client Side

public boolean receiveFile() {
        int current = 0;

        try {
            int bytesRead = bis.read(byteArr,0,byteArr.length);
            System.out.println("Receive file from : " + client);
            current = bytesRead;
            do {
                 bytesRead =
                 bis.read(byteArr, current, (byteArr.length-current));
                 if(bytesRead >= 0) current += bytesRead;
            } while(bytesRead != -1);
            bis.close();
            bos.write(byteArr, 0 , current);
            bos.flush();
            bos.close();
        } catch (IOException e) {
            System.out.println(e.getLocalizedMessage());
            disconnected();
            return false;
        }
        return true;

    }

Client side is multithreading,server side not use multithreading. I just paste some code that made problem if you want see all code please tell me.

After I debug the code, I found that if I set max thread to any and then the first thread always stuck in this loop. That bis.read(....) always return 0. Although, server had close stream and it not get out of the loop. I don’t know why … But another threads are work correctly.

do {
     bytesRead =
     bis.read(byteArr, current, (byteArr.length-current));
     if(bytesRead >= 0) current += bytesRead;
} while(bytesRead != -1);

Answer 1

How large is your input file (the one you send?) and how large is “byteArr”?
Also, by the time your check how many bytes are read, you already called bis.read(..) twice:

    int bytesRead = bis.read(byteArr,0,byteArr.length);

You probably want to read/send files larger than your buffer, so you probably want to do something like this:

        byte [] buffer = new byte[4096];
        int bytesRead;
        int totalLength = 0;

        while(-1 != (bytesRead = is.read(buffer))) {
            bos.write(buffer, 0, bytesRead);
            totalLength += bytesRead;
        }
        bos.close();
        is.close();

“is” would be a plain InputStream, Peter is right, you do not need to buffer it.