Java Port Socket Programming Error

Question

Hi- I have been working on a java client-server program using port sockets. The goal of this program is for the client to take a screenshot of the machine it is running on, break the RGB info of this image down into integers and arrays, then send this info over to the server, where it is reconstructed into a new image file. I run these files with two other small classes, which instantiate objects of these two files and execute their run() methods. However, when I run the program I am experiencing the following two bugs:

1. The first number received by the server, no matter what its value is according to the client, is always 49.
2. The client only sends(or the server only receives?) the first value, then the program hangs forever.

Any ideas as to why this is happening, and what I can do to fix it? The code for both client and server is below.

Thanks!

CLIENT:

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.*;
import java.net.Socket;
import java.text.SimpleDateFormat;
import java.util.*;
import javax.swing.*;
import javax.swing.Timer;


public class ViewerClient implements ActionListener{

 private Socket vSocket;
 private BufferedReader in;
 private PrintWriter out;
 private Robot robot; 
// static BufferedReader orders = null;

 public ViewerClient() throws Exception{
  vSocket = null;
  in = null;
  out = null;
  robot = null;  
 }

 public void setVSocket(Socket vs) {
  vSocket = vs;
 }

 public void setInput(BufferedReader i) {
  in = i;
 }

 public void setOutput(PrintWriter o) {
  out = o;
 }

 public void setRobot(Robot r) {
  robot = r;
 }

 /*************************************************/

 public Socket getVSocket() {
  return vSocket;
 }

 public BufferedReader getInput() {
  return in;
 }

 public PrintWriter getOutput() {
  return out;
 }

 public Robot getRobot() {
  return robot;
 }



 public void run() throws Exception{
  int speed = 2500;
  int pause = 5000;
  Timer timer = new Timer(speed, this);
  timer.setInitialDelay(pause);
//  System.out.println("CLIENT: Set up timer.");
  try {
   setVSocket(new Socket("Alex-PC", 4444));
   setInput(new BufferedReader(new InputStreamReader(getVSocket().getInputStream())));
   setOutput(new PrintWriter(getVSocket().getOutputStream(), true));
   setRobot(new Robot());
//   System.out.println("CLIENT: Established connection and IO ports.");
//   timer.start();
   captureScreen(nameImage());
  }catch(Exception e) {
   System.err.println(e);   
  }

 }

 public void captureScreen(String fileName) throws Exception{
  Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
  Rectangle screenRectangle = new Rectangle(screenSize);  
  BufferedImage image = getRobot().createScreenCapture(screenRectangle);
  int width = image.getWidth();
  int height = image.getHeight();
  int[] pixelData = new int[(width * height)];
  image.getRGB(0,0, width, height, pixelData, width, height);
  byte[] imageData = new byte[(width * height)];
  String fromServer = null;

  if((fromServer = getInput().readLine()).equals("READY")) {
   sendWidth(width);
   sendHeight(height);
   sendArrayLength((width * height));
   sendImageInfo(fileName);
   sendImageData(imageData);  

  }      


 }

 public String nameImage() throws Exception {
  String dateFormat = "yyyy-MM-dd HH-mm-ss";
  Calendar cal = Calendar.getInstance();
  SimpleDateFormat sdf = new SimpleDateFormat(dateFormat);
  String fileName = sdf.format(cal.getTime());
  return fileName;
 }

 public void sendArrayLength(int length) throws Exception {
  getOutput().println("SENDING ARRAY LENGTH...");
  getOutput().println(length);
 }

 public void sendWidth(int width) throws Exception {
  getOutput().println("SENDING IMAGE WIDTH...");
  getOutput().println(width);
 }

 public void sendHeight(int height) throws Exception {
  getOutput().println("SENDING IMAGE HEIGHT...");
  getOutput().println(height);
 }

 public void sendImageData(byte[] imageData) throws Exception {
  getOutput().println("SENDING IMAGE...");  
  for(int i = 0; i < imageData.length; i++) {
   getOutput().println(imageData[i]);
  }
 }

 public void sendImageInfo(String info) throws Exception {
  getOutput().println("SENDING IMAGE INFO...");  
  getOutput().println(info);
 }


 public void actionPerformed(ActionEvent a){
  String message = null;
  try {
   if((message = getInput().readLine()).equals("PROCESSING...")) {
    if((message = getInput().readLine()).equals("IMAGE RECIEVED SUCCESSFULLY.")) {
     captureScreen(nameImage());
    }
   }
  }catch(Exception e) {
   JOptionPane.showMessageDialog(null, "Problem: " + e);
  }

 }

}

SERVER:

import java.awt.image.BufferedImage;
import java.io.*;
import java.net.*;
import javax.imageio.ImageIO;  


public class ViewerServer {

 private ServerSocket vServer;
 private Socket vClient;
 private PrintWriter out;
 private BufferedReader in;
 private byte[] imageData;
 private int width;
 private int height;
 private String imageInfo; 
 private int[] rgbData;
 private boolean active;

 public ViewerServer() throws Exception{
  vServer = null;
  vClient = null;
  out = null;
  in = null;
  imageData = null;
  width = 0;
  height = 0;
  imageInfo = null;
  rgbData = null;
  active = true;
 }

 public void setVServer(ServerSocket vs) {
  vServer = vs;
 }

 public void setVClient(Socket vc) {
  vClient = vc;
 }

 public void setOutput(PrintWriter o) {
  out = o;
 }

 public void setInput(BufferedReader i) {
  in = i;
 }

 public void setImageData(byte[] imDat) {
  imageData = imDat;
 }

 public void setWidth(int w) {
  width = w;
 }

 public void setHeight(int h) {
  height = h;
 }

 public void setImageInfo(String im) {
  imageInfo = im;
 }

 public void setRGBData(int[] rd) {
  rgbData = rd;
 }

 public void setActive(boolean a) {
  active = a;
 }

 /***********************************************/


 public ServerSocket getVServer() {
  return vServer;
 }

 public Socket getVClient() {
  return vClient;
 }

 public PrintWriter getOutput() {
  return out;
 }

 public BufferedReader getInput() {
  return in;
 }

 public byte[] getImageData() {
  return imageData;
 }

 public int getWidth() {
  return width;
 }

 public int getHeight() {
  return height;
 }

 public String getImageInfo() {
  return imageInfo;
 }

 public int[] getRGBData() {
  return rgbData;
 }

 public boolean getActive() {
  return active;
 }


 public void run() throws Exception{
  connect();
  setActive(true);  
  while(getActive()) {
   recieve();
  }  
  close();
 }


 public void recieve() throws Exception{  
  String clientStatus = null;
  int clientData = 0;

//  System.out.println("SERVER: Sending ready message...");
  getOutput().println("READY");
//  System.out.println("SERVER: Ready message sent.");
  if((clientStatus = getInput().readLine()).equals("SENDING IMAGE WIDTH...")) {
   setWidth(getInput().read());
   System.out.println("Width: " + getWidth());
  }
  if((clientStatus = getInput().readLine()).equals("SENDING IMAGE HEIGHT...")) {
   setHeight(getInput().read());
   System.out.println("Height: " + getHeight());
  }
  if((clientStatus = getInput().readLine()).equals("SENDING ARRAY LENGTH...")) {
   clientData = getInput().read();   
   setImageData(new byte[clientData]);   
   System.out.println("Array length: " + clientData);
  }
  if((clientStatus = getInput().readLine()).equals("SENDING IMAGE INFO...")) {
   setImageInfo(getInput().readLine());
   System.out.println("Image Info: " + getImageInfo());
  }
  if((clientStatus = getInput().readLine()).equals("SENDING IMAGE...")) {
   for(int i = 0; i < getImageData().length; i++) {
    getImageData()[i] = ((byte)getInput().read());
   }
  }

  if((clientStatus = getInput().readLine()).equals("FINISHED.")) {
   getOutput().println("PROCESSING...");
   setRGBData(new int[getImageData().length]);
   for(int i = 0; i < getRGBData().length; i++) {
    getRGBData()[i] = getImageData()[i];
   }
   BufferedImage image = null;
   image.setRGB(0, 0, getWidth(), getHeight(), getRGBData(), getWidth(), getHeight());
   ImageIO.write(image, "png", new File(imageInfo + ".png")); //create an image file out of the screenshot

   getOutput().println("IMAGE RECIEVED SUCCESSFULLY.");
  }
 }

 public void connect() throws Exception  {
  setVServer(new ServerSocket(4444)); //establish server connection
//  System.out.println("SERVER: Connection established.");
  setVClient(getVServer().accept());  //accept client connection request
//  System.out.println("SERVER: Accepted connection request.");
  setOutput(new PrintWriter(vClient.getOutputStream(), true));  //set up an output channel
  setInput(new BufferedReader(new InputStreamReader(vClient.getInputStream())));  //set up an input channel
//  System.out.println("SERVER: Created IO ports.");
 }

 public void close() throws Exception {
  getOutput().close();
  getInput().close();
  getVClient().close();
  getVServer().close();
 }
}

Answer 1

You don't show us how your run the client or server. It appears you are not using threads in either which is required for socket io

You have many many errors I don't even know where to begin.

You are calling read() in BufferedReader It returns an integers, but its an integer that ranges only from 0-255. Yes I know its a bad interface, but you are only read a byte, not the full width and height.

My suggestion is to break down your program and make sure you understand how to send a single byte first. Write a program that uses sockets to send Hello World. Given the code you have shown I don't think you even can do that yet.