Simple FTP server

simpleFTP.java

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package ftpjava;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 *
 * @author ramana
 */
public class Server implements Runnable {

    public static void main(String [] args) throws IOException{
        new Thread(new Server()).start();
    }
    @Override
    public void run() {
        try {
            ServerSocket servSocket = new ServerSocket(8880);
            Socket fSock = servSocket.accept();
            while(true){
                try {
                    String message;
                    while(((message = new BufferedReader(new
                                    InputStreamReader(fSock.getInputStream()))
                            .readLine()) != null )){
                        boolean operator = messageParser(message);
                        OutputStream ostream = fSock.getOutputStream();
                        if(operator == true){
                            sendFile(ostream, message);
                        }
                    }
                    
                } catch (IOException ex) {
                    Logger.getLogger(Server.class.getName()).
                            log(Level.SEVERE, null, ex);
                }

            }
        } catch (IOException ex) {
            Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
    
    
    private boolean messageParser(String message){
        boolean return_value;
        final String pattern = "^!file:";
        Pattern ptr = Pattern.compile(pattern);
        Matcher match = ptr.matcher(message);
        if(!(match.find())){
            return_value = true;    
        }else {
            return_value = false;
        }
        return return_value;
    }
    //StoresFile on the server
    private void StoresFile(InputStream is) throws IOException{
        int max_size = 99999;
        byte[] byarr = new byte[max_size];
        BufferedOutputStream bostream =  new BufferedOutputStream
        (new FileOutputStream("received"));
        int bysize, currentSize = 0;
        bysize = is.read(byarr, 0, byarr.length);
        currentSize = bysize;
        
        do {
            bysize = is.read(byarr, currentSize, (bysize-currentSize));
            if(bysize > 0){
                currentSize += bysize;
            }
            
        }while(bysize>-1);
        
        bostream.write(byarr, 0, bysize);
        bostream.flush();
        bostream.close();
    }
    
   
    private void sendFile(OutputStream os, String PathToFile) throws IOException{
        File file_object = new File(PathToFile);
        BufferedInputStream bistream = new BufferedInputStream
        (new FileInputStream(file_object));
        byte[] bytearray = new byte[(int) file_object.length()];
        bistream.read(bytearray, 0, (int) file_object.length());
        os.write(bytearray);
        os.flush();
    }
}