FileServer

import java.net.*;
import java.io.*;

public class FileServer {
    static ServerSocket servSock;
    static Socket initSocket;
    static String fileSize = "";
    static File myFile = new File("attachment.pdf");
    static byte [] byteArr;
    static FileInputStream fis;
    static BufferedInputStream bis;
    static OutputStream os;
    static final int MAX_THREAD = 3;
    static String[] startAndEnd;
    public static void main(String[] args) throws IOException {

        System.out.println("Waiting...");
        if (!initSocket())
            return;
        if (!sendFileSize())
            return;
        if(!initFile())
            return;

        while(true){
            listenRecieveConnection();
            receiveOffsetFile();
            sendFile();
        }

    }

    public static boolean initSocket() {
        try {
            servSock = new ServerSocket(13267);
        } catch (IOException e) {
            System.out.println(e.getLocalizedMessage());
            disconnected();
            return false;
        }
        try {
            initSocket = servSock.accept();
        } catch (IOException e) {
            System.out.println(e.getLocalizedMessage());
            disconnected();
            return false;
        }
        System.out.println("Accepted connection : " + initSocket);
        return true;
    }

    public static boolean initFile() {
         try {
            fis = new FileInputStream(myFile);
            bis = new BufferedInputStream(fis);
            byteArr = new byte [(int)myFile.length()];
            bis.read(byteArr,0,byteArr.length);
        } catch (IOException e) {
            System.out.println(e.getLocalizedMessage());
            return false;
        }
        return true;
    }

    public static boolean sendFileSize() {
        fileSize += myFile.length() + "\n";
        try {
            os = initSocket.getOutputStream();
            os.write(fileSize.getBytes(),0,fileSize.getBytes().length);
            os.flush();
        } catch (IOException e) {
            System.out.println(e.getLocalizedMessage());
            disconnected();
            return false;
        }
        return true;

    }

    public static void disconnected() {
        try {
            servSock.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static boolean listenRecieveConnection() {
        try {
            initSocket = servSock.accept();
        } catch (IOException e) {
            System.out.println(e.getLocalizedMessage());
            disconnected();
            return false;
        }
        System.out.println("Accepted connection : " + initSocket);
        return true;
    }

    public static boolean receiveOffsetFile() {
        try {
            BufferedReader in = new BufferedReader(new InputStreamReader(initSocket.getInputStream()));
            String line =in.readLine();
            startAndEnd = line.split(" ");
        } catch (IOException e) {
            System.out.println(e.getLocalizedMessage());
            disconnected();
            return false;
        }
        return true;
    }

    public static boolean sendFile() {
        int start = Integer.parseInt(startAndEnd[0]) - 1;
        int end = Integer.parseInt(startAndEnd[1]) - 1;
        int size = (end - start) + 1;
        try {
            os = initSocket.getOutputStream();
            os.write(byteArr,start,size);
            os.flush();
            System.out.println("Send file to : " + initSocket);
        } catch (IOException e) {
            System.out.println(e.getLocalizedMessage());
            disconnected();
            return false;
        }
        return true;
    }

}