JavaProgramForEchoServerAndEchoClient

 

Java:

Program:

EchoServer:

import java.io.*;

import java.net.*;

public class EServer {

public static void main(String args[]) {

try (ServerSocket s = new ServerSocket(9000);

Socket c = s.accept();

DataInputStream is = new DataInputStream(c.getInputStream());

PrintStream ps = new PrintStream(c.getOutputStream())) {

while (true) {

ps.println(is.readLine());

}

} catch (IOException e) {

System.out.println(e);

}

}

}

EchoClient:

import java.io.*;

import java.net.*;

public class EClient {

public static void main(String arg[]) {

try (Socket c = new Socket(InetAddress.getLocalHost(), 9000);

PrintStream os = new PrintStream(c.getOutputStream());

DataInputStream is = new DataInputStream(System.in);

DataInputStream is1 = new DataInputStream(c.getInputStream())) {

while (true) {

System.out.print("Client: ");

String line = is.readLine();

os.println(line);

System.out.println("Server: " + is1.readLine());

}

} catch (IOException e) {

System.out.println("Socket Closed!");

}

}

}

Output:

Server

C:\Program Files\Java\jdk1.5.0\bin>javac EServer.java

C:\Program Files\Java\jdk1.5.0\bin>java EServer

C:\Program Files\Java\jdk1.5.0\bin>

Client

C:\Program Files\Java\jdk1.5.0\bin>javac EClient.java

C:\Program Files\Java\jdk1.5.0\bin>java EClient

Client: Hai Server Server:Hai Server

Client: Hello Server:Hello

Client:end Server:end

Client:ds

Socket Closed!

Chat

Chat Server:

import java.io.*;

import java.net.*;

public class ChatServer {

public static void main(String[] args) {

try (ServerSocket serverSocket = new ServerSocket(9000)) {

System.out.println("Chat Server is running. Waiting for clients to connect...");

Socket clientSocket = serverSocket.accept();

System.out.println("Client connected: " + clientSocket.getInetAddress());

BufferedReader reader = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));

PrintWriter writer = new PrintWriter(clientSocket.getOutputStream(), true);

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

while (true) {

// Read message from the client

String clientMessage = reader.readLine();

if (clientMessage == null || clientMessage.equalsIgnoreCase("bye")) {

break;

}

System.out.println("Client: " + clientMessage);

// Read message from the server console and send it to the client

System.out.print("Server: ");

String serverMessage = consoleReader.readLine();

writer.println(serverMessage);

}

} catch (IOException e) {

e.printStackTrace();

}

}

}

Chat Client:

import java.io.*;

import java.net.*;

public class ChatClient {

public static void main(String[] args) {

try (Socket clientSocket = new Socket("localhost", 9000);

BufferedReader reader = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));

PrintWriter writer = new PrintWriter(clientSocket.getOutputStream(), true);

BufferedReader consoleReader = new BufferedReader(new InputStreamReader(System.in))) {

System.out.println("Connected to Chat Server.");

while (true) {

// Read message from the server

String serverMessage = reader.readLine();

if (serverMessage == null || serverMessage.equalsIgnoreCase("bye")) {

break;

}

System.out.println("Server: " + serverMessage);

// Read message from the client console and send it to the server

System.out.print("Client: ");

String clientMessage = consoleReader.readLine();

writer.println(clientMessage);

}

} catch (IOException e) {

e.printStackTrace();

}

}

}

Output:

# Terminal 1 (ChatServer)

Chat Server is running. Waiting for clients to connect...

Client connected: /127.0.0.1

Client: Hello Server

Server: Hi there! How can I help you?

Client: What's the weather like today?

Server: I'm just a simple chat server. I don't know about the weather!

Client: bye

# Terminal 2 (ChatClient)

Connected to Chat Server.

Server: Hi there! How can I help you?

Client: How are you doing?

Server: I'm just a simple chat server. I don't have feelings!

Client: bye

File Transfer

FileTransferServer.java:

import java.io.*;

import java.net.*;

public class FileTransferServer {

private static final int PORT = 9000;

private static final String FILE_DIRECTORY = "files/";

public static void main(String[] args) {

try (ServerSocket serverSocket = new ServerSocket(PORT)) {

System.out.println("File Transfer Server is running. Waiting for clients to connect...");

while (true) {

Socket clientSocket = serverSocket.accept();

System.out.println("Client connected: " + clientSocket.getInetAddress());

try (BufferedReader reader = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));

PrintWriter writer = new PrintWriter(clientSocket.getOutputStream(), true)) {

String fileName = reader.readLine();

System.out.println("Client requested file: " + fileName);

try {

sendFile(fileName, writer);

} catch (FileNotFoundException e) {

writer.println("File not found: " + fileName);

}

}

}

} catch (IOException e) {

e.printStackTrace();

}

}

private static void sendFile(String fileName, PrintWriter writer) throws IOException {

String filePath = FILE_DIRECTORY + fileName;

try (BufferedReader fileReader = new BufferedReader(new FileReader(filePath))) {

String line;

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

writer.println(line);

}

writer.println("FileTransferComplete"); // Signal to the client that the file transfer is complete

System.out.println("File transfer successful.");

}

}

}

FileTransferClient.java:

import java.io.*;

import java.net.*;

public class FileTransferClient {

private static final int PORT = 9000;

public static void main(String[] args) {

try (Socket socket = new Socket("localhost", PORT);

BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));

PrintWriter writer = new PrintWriter(socket.getOutputStream(), true);

BufferedReader consoleReader = new BufferedReader(new InputStreamReader(System.in))) {

System.out.println("Connected to File Transfer Server.");

System.out.print("Enter the file name: ");

String fileName = consoleReader.readLine();

writer.println(fileName);

String response = reader.readLine();

if (response.startsWith("File not found")) {

System.out.println(response);

} else {

System.out.println("File content received:");

while (true) {

String line = reader.readLine();

if (line.equals("FileTransferComplete")) {

break;

}

System.out.println(line);

}

}

} catch (IOException e) {

e.printStackTrace();

}

}

}

FileTransferServer Output:

File Transfer Server is running. Waiting for clients to connect...

Client connected: /127.0.0.1

Client requested file: sample.txt

File transfer successful.

FileTransferClient Output:

Connected to File Transfer Server.

Enter the file name: sample.txt

File content received:

This is a sample file.

It contains some text for testing.

FileTransferComplete