Thread: I am trying to make a messenger program!

I got to do a kind of Messenger in Java. Well .. it will not have to do something with a server or making accounts. Will simply be a program which will be used to communicate between 2 computers into a network, by setting the IP of the computers that communicate. I think to make a window with a smaller text area where each user writes the messages and another text area where each message will appear after the user touches a SEND key. I am asking if there are any packages or classes which will help me to make the second text area easier. I already seen that i have JavaFrameWork to broadcast an audio/video file on this messenger. Yeah, i have to add video/audio options too but if i manage to make it work with sending message, it will be much easier to finish it.

Are you going to write both a server and client code? There are dozens of sample programs from students on the forums.

basically on each computer should run 2 Threads:
one of them sends the message having the role of server and the other one receives the message having the role of client!

Are you saying that Each PC is a server that other PCs can connect to directly. No master server.
How do the PCs get the IP addresses of the other PCs?

So far, i manged to make it work fine with sending text message. Now i want to make my messenger to send a file from one user to the other. But i do not manage to make 2 simple sockets to send one file to another. I have found one already done...i changed it a little and seems it works very strage!
Here is the code for the socket sending the file

 
package testServerFisier;
 
import java.io.*;
import java.io.IOException;
import java.net.*;
 
public class TestFisier
 
{
	public static void main (String [] args ) throws IOException
	{
	    // create socket
	    ServerSocket servsock = new ServerSocket(8555);
	    while (true)
	    {
	      System.out.println("Waiting...");
 
	      Socket sock = servsock.accept();
	      System.out.println("Accepted connection : " + sock);
 
	      // sendfile
	      File myFile = new File ("C:\\Users\\nikipiulitza\\Desktop\\poze\\kazi1.bmp");
	      byte [] mybytearray  = new byte [(int)myFile.length()];
	      FileInputStream fis = new FileInputStream(myFile);
	      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();
	      sock.close();
	      }
	}
 
}

And here is the code for the socket that receives the file :

package testPrimireFisier;
 
import java.io.*;
import java.io.IOException;
import java.net.*;
public class TestClientFisier
{
	  public static void main (String [] args ) throws IOException
 
	  {
    int filesize=77507; // filesize temporary hardcoded
 
    long start = System.currentTimeMillis();
    int bytesRead;
    int current = 0;
    // localhost for testing
    Socket sock = new Socket("192.168.0.100",8555);
    System.out.println("Connecting...");
 
    // receive file
    byte [] mybytearray  = new byte [filesize];
    InputStream is = sock.getInputStream();
    FileOutputStream fos = new FileOutputStream("C:\\Users\\nikipiulitza\\Desktop\\poze\\kazi2.bmp");
    BufferedOutputStream bos = new BufferedOutputStream(fos);
    bytesRead = is.read(mybytearray,0,mybytearray.length);
    current = bytesRead;
 
    // thanks to A. Cádiz for the bug fix
    do {                                                      // HERE is it where it stucks
       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();
  }
 
}

Looke like the server sends the file properly, but i detected at it something that may be the source of the problem :
At the line with

System.out.println("Accepted connection : " + sock);

I get

Accepted connection : Socket[addr=/192.168.0.100,port=55403,localport=8555]

So, the IP is correctly, the one i have written at the client's socket constructor. But here, i got a port that has changed ! I am not sure, but i think that the port of the client has changed ! Why ? Can it be a problem that i run both programs on same computer ? On the messenger itself, i use Datagram sockets and when i connect to my computer, it works with sending text messages. Any clue where and how can i find why the port is changing ?
I modified these programs little more and turned them into Threads, and added them on my messenger code, and seems its same thing which does not allow the files to be sent.

its same thing which does not allow the files to be sent.

What is written to the output file? Is there a problem with it?

The code basically works for me when I use localhost.

Yeah, you are right. I think it cannot send a .bmp file properly, or maybe it cannot crate a bytearray that large, as the bmp file dimension. I tried to send a .txt file which is smaler and it worked. Now i have one more problem. I used the code of these into Thread classes in my messenger code. But i have problems with socket receiving the file. I start the thread which receives the file inside the thread which usually receives the messenger's text. When one user chooses to send a file, the thread which sends messages sends a message containing the word FILE+dimension of the file+ the name of the file. And then, the thread receiving this message will know to start the thread with the socked which receive the file. I used a lot of println and am sure that the thread which receive the file is starting properly (maybe it is wrong that i start a thread inside another thread ? ). but seems that

do { // HERE is it where it stucks
bytesRead =
is.read(mybytearray, current, (mybytearray.length-current));
if(bytesRead >= 0) current += bytesRead;
} while(bytesRead > -1);

does only receive 0 value, and the do-while bubble does not end .
Any clue why it may happen like that ? i tried to send same .txt file which worked on the programs i shown upper, and the socket receiving the file creates the .txt file, but does not receive any byte to write to it .

Your code has a hard coded filesize variable. Is the size correct for the file you are trying to send?

Yeah, that works properly! The size of the file is sent to the main serversocket of my messenger, inside the String containing the word FILE. I have "cut " the String and got the size from that String and used to for the constructor of the Thread which receive the file. I also used println for that and when the thread runs, the size of the bytearray is correctly set.

If it works properly, please explain the problem.

Well , seems there is something wrong with Threads that send/receive the file.
I made some classes separated from the messenger project, and i discovered that they actually have a problem (not the way i used them in the main project).

Here is the Thread that is sending the file :

package testServerFisier;
import java.io.*;
import java.net.*;
 
public class ThreadSendFisier extends Thread
{
 
	String url;
 
	public ThreadSendFisier(String url ) 
	{
		this.url =url;
 
	}
 
 
	public void run ()
	{
 
 
 
		try
		{
			  ServerSocket servsock = new ServerSocket(8221);
			    while (true) 
			    {
			      System.out.println("Waiting...");
 
			      Socket sock = servsock.accept();
			      System.out.println("Accepted connection : " + sock);
 
			      // sendfile
			      File myFile = new File (url);
			      byte [] mybytearray  = new byte [(int)myFile.length()];
			      System.out.println((int)myFile.length());
 
			      FileInputStream fis = new FileInputStream(myFile);
			      BufferedInputStream bis = new BufferedInputStream(fis);
			      bis.read(mybytearray,0,mybytearray.length);
			      OutputStream os = sock.getOutputStream();
 
			      System.out.println("Dimensiunea array la trimitere: " + mybytearray.length);
			      os.write(mybytearray,0,mybytearray.length);
 
			      os.flush();
			      sock.close();
 
 
			    }
		}
		catch (Exception e)
		{
			e.printStackTrace();
		}
	}	
}
 
   // this is the class with the main method : 
 
package testServerFisier;
 
public class TestThreadSend 
{
	public static void main(String[] args)
	{
		new ThreadSendFisier("C:\\Users\\nikipiulitza\\Desktop\\poze\\fisierSend.txt").start();
	}
 
}

And there is the Thread which receives the file:

package testServerFisier;
import java.io.*;
import java.net.*;
 
import mainPack.FereastraPrincipala;
 
 
 
public class ThreadFisierPrimire extends Thread
 
{
 
 
	String url;
	int filesize;
 
 
	ThreadFisierPrimire( String url, int filesize)
	{
 
		this.url = url;
		this.filesize = filesize;
	}
 
 
	public void run()
	{
 
		try
		{
 
 
		    long start = System.currentTimeMillis();
		    int bytesRead;
		    int current = 0;
		    // localhost for testing
		    Socket sock = new Socket("192.168.0.100",8221);
		    System.out.println("Connecting...");
		    System.out.println("Socket primire: "+sock);
		    // receive file
 
		    byte [] mybytearray  = new byte [filesize];
 
		    InputStream is = sock.getInputStream();
		    FileOutputStream fos = new FileOutputStream(url);
		    BufferedOutputStream bos = new BufferedOutputStream(fos);
		    bytesRead = is.read(mybytearray,0,mybytearray.length);
		    current = bytesRead;
 
		    System.out.println(sock.toString());
 
		       do {
 
		    	   bytesRead = is.read(mybytearray, current, (mybytearray.length-current));
 
		       		} while(bytesRead > -1);
 
		    bos.write(mybytearray, 0 , current);
		    bos.flush();
		    long end = System.currentTimeMillis();
		    System.out.println(end-start);
		    bos.close();
		    sock.close();
			System.out.println("File Received");
			this.notifyAll();
		}
 
	    catch (Exception e)
	    {
 
	    	e.printStackTrace();
 
	    }
	}
 
}
 
   // and the class with the main method using this thread:
 
package testServerFisier;
 
public class TestThread
{
	public static void main(String[] args)
	{
		new ThreadFisierPrimire("C:\\Users\\nikipiulitza\\Desktop\\poze\\fisierSend2.txt",17).start();
 
	}
 
}

I think I have noticed where is something going wrong, it happens at the thread which receives the file :

do {

bytesRead = is.read(mybytearray, current, (mybytearray.length-current));

} while(bytesRead > -1);

Here, if i println bytesRead , i only get 0 and the bubble does not end.
But sadly, i do not understand why .
Is there anything wrong if i use these sockets inside of some Threads ? There code is nearly same as of the first programs which have the sockets build and running in the main method. But these do not work as the others did with same small .txt file.

Add some printlns in the loop to print out the values of bytesRead and current to see what the code is doing. Compare to the value of filesize.

Also you need to read the API doc for the read() method to be sure you understand how to use it.

Hah ...finally i managed make it work ....i should have not changed the filesize variable to the size of the file....because it makes that bytearray length and current to have same value...so that is why i was getting 0 at each run of the bubble !

Your code is too simple minded. It needs to read some bytes in and write those bytes out in a loop until there are no more bytes to be read.