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Networking programs

 01 programs

import java.net. * ;

import java.io.*;

class Ports

{

public static void main (String [] args) throws Exception

{

InetAddress h = InetAddress.getLocalHost();

String host =h. getHostName();

String haddr = h. getHostAddress(); 

System.out.println("\nHost Name: :"+ host); 

System.out.println("In Host Address:: "+haddr);

for (int i=0; i < 1024; i++)

{

Socket s=null;

try 

{

s = new Socket ((host), i);

System.out.println(" port "+ i + "Active");

}

catch (SocketException se)

{

}

catch(Exception e)

{

System.out.println(" Error....");

}

}

}

}

Output:-













02 -program

2 a)

import java.io.*;

import java.net. *;

import java.lang. * ;


class chats extends Thread

{

public static void main (String args [])

{

try

{

ServerSocket ss = new ServerSocket (111); 

System.out.println ("server ready "); 

Socket s = ss.accept ();

BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

BufferedReader br = new BufferedReader(new InputStreamReader (s. getInputStream()));

PrintWriter pw=new PrintWriter (new OutputStreamWriter(s. getOutputStream()));

while(true)

{

String msg = br.readLine();

System.out.println(" from client: "+msg); 

if (msg. equals ("quit "))

{

System.out. println("disabled");

break;

}

System.out.println("server");

msg = in.readLine();

pw.println (msg);

pw.flush();

}

}

catch (IOException e)

{

System.out.println ("error");

}

}

}

02) b)
import java .net.*;
import java.io.*;
import java.lang.*;
public class chat
{
public static void main(String[]args)
{
try
{
Socket s = new Socket("localhost", 111);
BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
BufferedReader br=new BufferedReader(new InputStreamReader(s.getInputStream()));
PrintWriter pw=new PrintWriter(new OutputStreamWriter(s.getOutputStream()));
while(true)
{
System.out.println("client");
String msg=in.readLine();
pw.println("msg");
pw.flush();
String from=br.readLine();
System.out.println("from server="+from);
if(from.equals("quit"))
{
System.out.println("disconnect");
System.exit(0);
}
}
}
catch(IOException e)
{
System.out.println("ending");
}
}
}



03) a)
import java.io.*;
import java.net.*;
import java.sql.*;

public class JDBCServer {
    private static final String DB_URL = "jdbc:mysql://localhost:3306/soft";
    private static final String USER = "root";
    private static final String PASSWORD = "1234";

    public static void main(String[] args) {
        try (ServerSocket serverSocket = new ServerSocket(5000)) {
            System.out.println("Server is listening on port 5000...");
            
            while (true) {
                Socket socket = serverSocket.accept();
                System.out.println("Client connected.");
                
                try (BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                     PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
                     Connection connection = DriverManager.getConnection(DB_URL, USER, PASSWORD)) {

                    String query = in.readLine();  // Read query from client
                    System.out.println("Received query: " + query);
                    
                    try (Statement stmt = connection.createStatement();
                         ResultSet rs = stmt.executeQuery(query)) {
                        while (rs.next()) {
                            out.println(rs.getString(1));  // Send results to client (adjust as needed)
                        }
                    }
                    
                    out.println("END");  // Indicate the end of results
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}


3) b)

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

public class JDBCClient {
    public static void main(String[] args) {
        String serverAddress = "localhost";  // Server address
        int port = 5000;                     // Server port
        
        try (Socket socket = new Socket(serverAddress, port);
             PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
             BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()))) {

            String query = "SELECT * FROM your_table";  // Replace with your actual query
            out.println(query);  // Send query to server
            
            System.out.println("Results from server:");
            String response;
            while ((response = in.readLine()) != null) {
                if ("END".equals(response)) {
                    break;  // End of results
                }
                System.out.println(response);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}




4A)


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

public class FTPServer1 
{
    public static void main(String[] args) 
    {
        try (ServerSocket ss = new ServerSocket(9000)) 
        {
            System.out.println("Server started on port 9000.");
            while (true) 
            {
                try (Socket s = ss.accept();
                DataInputStream id = new DataInputStream(s.getInputStream());
                PrintStream p = new PrintStream(s.getOutputStream())) 
                {
                    System.out.println("Client connected.");

                    // Read the filename from the client
                    String filename = id.readLine();
                    System.out.println("Requested file: " + filename);

                    // Open the requested file
                    File file = new File(filename);
                    if (!file.exists() || file.isDirectory()) 
                    {
                        p.println("Error: File not found.");
                        System.out.println("File not found: " + filename);
                        continue;
                    }

                    try (FileInputStream fis = new FileInputStream(file)) 
                    {
                        int ch;
                        while ((ch = fis.read()) != -1) 
                        {
                            p.write(ch); // Send file content to client
                        }
                        System.out.println("File sent successfully.");
                    } catch (IOException e) 
                    {
                        System.err.println("Error reading file: " + e.getMessage());
                    }
                } catch (IOException e) 
                {
                    System.err.println("Connection error: " + e.getMessage());
                }
            }
        } catch (IOException e) 
        {
            System.err.println("Server error: " + e.getMessage());
        }
    }
}


4B)

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

public class ftpclient
{
public static void main(String args[]) throws Exception
{
Socket s = new Socket ("Localhost", 9000); 
BufferedReader d1 =new BufferedReader (new InputStreamReader (s.getInputStream()));
InputStream in = s. getInputStream();
DataInputStream di = new DataInputStream (System.in); 
PrintStream p = new PrintStream (s.getOutputStream()); 
System. out. println ("Enter absolute. Path") ;
String st = di. readLine(); 
p. println (st);
System.out.println("enter destination"); 
String file = di. readLine();
FileOutputStream fos = new FileOutputStream(file);
int ch;
while ((ch=d1.read() )!= -1)
{
System.out.println ((char)ch); 
fos. write (ch);
}
}
}



5a)
import java.io.*;
import java.net.*;

// Server Thread Class
class tftpms extends Thread 
{
    private DatagramSocket ds;

    // Constructor
    tftpms(DatagramSocket ds) {
        this.ds = ds;
        start(); // Start the thread
    }

    @Override
    public void run() {
        try {
            int POS = 0;
            int buff_size = 2000;
            byte[] buff = new byte[buff_size];

            // Receiving packet
            DatagramPacket dp = new DatagramPacket(buff, buff.length);
            ds.receive(dp);

            // Extracting the filename
            String filename = new String(dp.getData(), 0, dp.getLength());
            System.out.println("Requested file: " + filename);

            // Reading the file
            FileInputStream fis = new FileInputStream(filename);
            int c;
            while ((c = fis.read()) != -1) {
                buff[POS++] = (byte) c;

                // Send data when buffer is full
                if (POS == buff_size) {
                    ds.send(new DatagramPacket(buff, POS, InetAddress.getLocalHost(), 50));
                    POS = 0; // Reset the buffer position
                }
            }

            // Sending the remaining data
            if (POS > 0) {
                ds.send(new DatagramPacket(buff, POS, InetAddress.getLocalHost(), 50));
            }

            fis.close(); // Close the file input stream
            System.out.println("File sent successfully.");
        } catch (Exception e) {
            System.err.println("Error in file transfer: " + e.getMessage());
            e.printStackTrace();
        }
    }
}

// Main Server Class
class tftpserver {
    public static void main(String args[]) throws Exception {
        System.out.println("Server is ready...");

        // Initialize DatagramSocket on port 69
        DatagramSocket ds = new DatagramSocket(69);

        // Start the server thread
        new tftpms(ds);
    }
}


5b)
import java.io.*;
import java.net.*;

// TFTP Client Class
class tftpclient1 {
    public static void main(String[] args) {
        new tftpc();
    }
}

// Client Logic Class
class tftpc {
    private DatagramSocket ds;
    private int buff_Size = 2000;
    private byte[] buff = new byte[buff_Size];

    // Constructor
    tftpc() {
        try {
            // Initialize DatagramSocket
            ds = new DatagramSocket(50);
        } catch (Exception e) {
            System.err.println("Socket initialization error: " + e.getMessage());
            System.exit(0);
        }

        try (DataInputStream in = new DataInputStream(System.in)) {
            // Get file path from user
            System.out.println("Enter the absolute path of the file: ");
            String str = in.readLine();
            int pos = str.length();
            byte[] buf = str.getBytes();

            // Send file request to the server
            ds.send(new DatagramPacket(buf, pos, InetAddress.getLocalHost(), 69));
            System.out.println("Enter the name to save the file as: ");
            String stt = in.readLine();

            // Create file output stream to save the received file
            FileOutputStream fos = new FileOutputStream(stt);

            while (true) {
                // Receive data packets from the server
                DatagramPacket dp = new DatagramPacket(buff, buff.length);
                ds.receive(dp);

                // Check if the server has completed sending data
                if (dp.getLength() == 0) {
                    System.out.println("File transfer complete.");
                    break;
                }

                // Write received data to the file
                fos.write(dp.getData(), 0, dp.getLength());
            }

            // Close the file output stream
            fos.close();
            System.out.println("File saved successfully.");
        } catch (Exception e) {
            System.err.println("Error: " + e.getMessage());
            e.printStackTrace();
        } finally {
            if (ds != null && !ds.isClosed()) {
                ds.close(); // Close the DatagramSocket
            }
        }
    }
}



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