Hi all, I have created a UDP program, client and server. What i\'m trying to do

Question

Hi all, I have created a UDP program, client and server. What i'm trying to do is, hash a string, save the hasded code and the message into a .txt file and send it over to the server.

I have created the UDP program, MD5 hash codes and writing the output into a txt file. Cant seem to figure out how i could send the file over to my server. Can someone help me?

// Imports
import java.io.*;
import java.net.*;
// Class Client Socket
public class ClientSocket
{
    public static void main(String[] args) throws IOException
   {
       // show main Menu
        System.out.println("Basic Client Socket Programming");
       // Socket Variables
        Socket clientSocket = null;             // for sending and receiving of data
        PrintWriter outputStream = null;       // for sending data
        BufferedReader inputStream = null;       // for receiving data
       // Create and open socket
       // Connection to 127.0.0.1, port num=2001
        try
       {
            clientSocket = new Socket("127.0.0.1", 2001);
            outputStream = new PrintWriter(clientSocket.getOutputStream(), true);
            inputStream = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
        }
       catch (UnknownHostException e)
       {
            System.err.println("Don't know about host: 127.0.0.1");
           return;
       }
       catch (IOException e)
       {
            System.err.println("Couldn't get I/O for the connection to: 127.0.0.1");
           return;
        }
       // check if connection is successful
       if((clientSocket == null) || (outputStream == null) || (inputStream == null))
       {
           System.err.println("Socket Connection not successfull");
           return;
       }
       else
       {
           System.out.println("Socket Connected");
       }
        //generate MD5 and send data
        String hash = MD5.md5("Hello");
        System.out.println("Hash code generated: "+hash);
        //outputStream.println("Hello ||" + hash);
        //creates a new BufferWriter to write the hash value and the text message into the txt file.
        BufferedWriter out = new BufferedWriter(new FileWriter("hashedCode.txt"));
        out.write(hash); //writes the hash code to the file
        out.close(); //close the bufferreader
       //Send the file to the server
      
       // receiving data
       String rcvData;
       rcvData = inputStream.readLine();
       System.out.println(rcvData);
        // close connections
        try
        {
            outputStream.close();
            inputStream.close();
            clientSocket.close();
            System.out.println("Connection closed.");
        }
        catch (UnknownHostException e)
        {
            System.err.println("Trying to connect to unknown host: " + e);
        }
        catch (IOException e)
        {
            System.err.println("IOException: " + e);
        }
        // exit program
       return;
   }
}

// Imports
import java.io.*;
import java.net.*;
public class serverSocket
{
    public static void main(String[] args) throws IOException
   {
       // show main Menu
        System.out.println("Basic Client Socket Programming");
       // Socket Variables
        ServerSocket serverSocket = null;         // for listen for connection
        Socket rcvSocket = null;               // for sending n rcving data
        DataOutputStream outputStream = null;    // for sending data
        DataInputStream inputStream = null;       // for receiving data
        // try to open a socket to listen for incoming data
        // port number must match the one that the client is connecting to
        try
        {
           serverSocket = new ServerSocket(2001);
        }
        catch (IOException e)
        {
           System.err.println(e);
        }
        // creating a socket to rcv incoming data
        while (true)
        {
            try
            {
                System.out.println("Listening");
                rcvSocket = serverSocket.accept();
                System.out.println("Connected");
                PrintWriter out = new PrintWriter(rcvSocket.getOutputStream(), true);
                BufferedReader in = new BufferedReader(new InputStreamReader(rcvSocket.getInputStream()));
                // initiate conversation with client
                String rcvData = in.readLine();
                System.out.println("Rcv Data: " + rcvData);
                out.println(rcvData);
            }
            catch (IOException e)
            {
               System.err.println(e);
            }
        }
    }
}

Explanation / Answer

The issue here is to send the file (a text file containing the message and the hashcode).

Read the file and send to the socket as follows:
try {
FileInputStream fin = new FileInputStream("hashedCode.txt");
Scanner sc = new Scanner(fin);

DataOutputStream out=new DataOutputStream(clientSocket.getOutputStream());
while(sc.hasNextLine()){
   String line = sc.nextLine()
   out.writeUTF(line);
}
sc.close();
out.close();

}
catch(Exception e){
    e.printStackTrace();
}

The code has been inserted in your client file.

import java.io.*;
import java.net.*;
// Class Client Socket
public class ClientSocket
{
    public static void main(String[] args) throws IOException
   {
       // show main Menu
        System.out.println("Basic Client Socket Programming");
       // Socket Variables
        Socket clientSocket = null;             // for sending and receiving of data
        PrintWriter outputStream = null;       // for sending data
        BufferedReader inputStream = null;       // for receiving data
       // Create and open socket
       // Connection to 127.0.0.1, port num=2001
        try
       {
            clientSocket = new Socket("127.0.0.1", 2001);
            outputStream = new PrintWriter(clientSocket.getOutputStream(), true);
            inputStream = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
        }
       catch (UnknownHostException e)
       {
            System.err.println("Don't know about host: 127.0.0.1");
           return;
       }
       catch (IOException e)
       {
            System.err.println("Couldn't get I/O for the connection to: 127.0.0.1");
           return;
        }
       // check if connection is successful
       if((clientSocket == null) || (outputStream == null) || (inputStream == null))
       {
           System.err.println("Socket Connection not successfull");
           return;
       }
       else
       {
           System.out.println("Socket Connected");
       }
        //generate MD5 and send data
        String hash = MD5.md5("Hello");
        System.out.println("Hash code generated: "+hash);
        //outputStream.println("Hello ||" + hash);
        //creates a new BufferWriter to write the hash value and the text message into the txt file.
        BufferedWriter out = new BufferedWriter(new FileWriter("hashedCode.txt"));
        out.write(hash); //writes the hash code to the file
        out.close(); //close the bufferreader
       //Send the file to the server

       FileInputStream fin = new FileInputStream("hashedCode.txt");
       Scanner sc = new Scanner(fin);

       DataOutputStream out=new DataOutputStream(clientSocket.getOutputStream());
       while(sc.hasNextLine()){
          String line = sc.nextLine()
          out.writeUTF(line);
       }
       sc.close();
       out.close();

}
catch(Exception e){
    e.printStackTrace();
}

     
       // receiving data
       String rcvData;
       rcvData = inputStream.readLine();
       System.out.println(rcvData);
        // close connections
        try
        {
            outputStream.close();
            inputStream.close();
            clientSocket.close();
            System.out.println("Connection closed.");
        }
        catch (UnknownHostException e)
        {
            System.err.println("Trying to connect to unknown host: " + e);
        }
        catch (IOException e)
        {
            System.err.println("IOException: " + e);
        }
        // exit program
       return;
   }
}

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