Socket Program: Client Requests File, Server Sends Content Back

package com.kartik.socket;

import java.io.*;

import java.net.ServerSocket;

import java.net.Socket;

public class SocketServerExample {

    private static ServerSocket server;

    private static int port = 9876; // Port to listen to client requests

    public static void main(String args[]) throws IOException, ClassNotFoundException {

        server = new ServerSocket(port); // Start the server

        // Keep listening indefinitely until an 'exit' request

        while (true) {

            System.out.println("Waiting for client request");

            Socket socket = server.accept(); // Accept client connection

            // Receive file path from client

            ObjectInputStream objectInputStream = new ObjectInputStream(socket.getInputStream());

            String message = (String) objectInputStream.readObject();

            System.out.println("Message Received: " + message);

            File file = new File(message);

            ObjectOutputStream objectOutputStream = new ObjectOutputStream(socket.getOutputStream());

            if (file.exists()) {

                // Read the file and send content to client

                BufferedReader bufferReader = new BufferedReader(new FileReader(message));

                StringBuffer stringBuffer = new StringBuffer();

                String line;

                while ((line = bufferReader.readLine()) != null) {

                    System.out.println(line);

                    stringBuffer.append(line).append(System.lineSeparator());

                }

                objectOutputStream.writeObject(stringBuffer.toString());

                bufferReader.close();

            } else {

                // File not found, send error message

                System.out.println("File not found");

                objectOutputStream.writeObject("File is not there");

            }

            objectInputStream.close();

            objectOutputStream.close();

            socket.close();

            // Exit server if the client sends an 'exit' message

            if (message.equalsIgnoreCase("exit")) break;

        }

        server.close(); // Close the server

        System.out.println("Shutting down Socket server!!");

    }

}

package com.kartik.socket;

import java.io.IOException;

import java.net.UnknownHostException;

import java.util.Properties;

import java.util.Scanner;

public class SocketClientExample {

    public static void main(String[] args) throws UnknownHostException, ClassNotFoundException, IOException, InterruptedException {

        SocketClientImplement socketClientImplement = new SocketClientImplement();

        String domainName = null; // Domain name of the server

        int portNumberOfServer = 9876; // Default port number

        String fileName;

        String fileNameWithPath;

        // Console input for file name and path

        System.out.println("Enter the file name and path:");

        Scanner console = new Scanner(System.in);

        fileName = console.next(); // Input file name

        fileNameWithPath = console.next(); // Input file path

        // Call the server to get the file

        socketClientImplement.callSocketServer(domainName, portNumberOfServer, fileName, fileNameWithPath);

    }

}

package com.kartik.socket;

import java.io.*;

import java.net.InetAddress;

import java.net.Socket;

import java.net.UnknownHostException;

public class SocketClientImplement {

    public void callSocketServer(String domainName, int portNumberOfServer, String fileName, String filePath)

            throws UnknownHostException, IOException, ClassNotFoundException, InterruptedException {

        InetAddress host = (domainName != null) ? InetAddress.getByName(domainName) : InetAddress.getLocalHost();

        int port = (portNumberOfServer > 0) ? portNumberOfServer : 9876;

        // Prepare file path for the server

        String fullPath = filePathMethod(fileName, filePath);

        System.out.println("File path: " + fullPath);

        // Establish socket connection to server

        Socket socket = new Socket(host.getHostName(), port);

        // Send file path to the server

        ObjectOutputStream objectOutputStream = new ObjectOutputStream(socket.getOutputStream());

        System.out.println("Sending request to Socket Server");

        objectOutputStream.writeObject(fullPath);

        // Receive response from the server

        ObjectInputStream objectInputStream = new ObjectInputStream(socket.getInputStream());

        String message = (String) objectInputStream.readObject();

        System.out.println("Message: " + message);

        objectInputStream.close();

        objectOutputStream.close();

        socket.close();

    }

    public String filePathMethod(String fileName, String pathName) {

        String absoluteFilePath = pathName + (System.getProperty("os.name").toLowerCase().contains("win") ? "\\" : "/") + fileName;

        System.out.println("Final file path: " + absoluteFilePath);

        return absoluteFilePath;

    }

}