WebSocketClient.java

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

public class WebSocketClient {
    
    private static Socket socket;
    private static OutputStream out;
    private static InputStream in;
    
    public static void main(String[] args) {
        try {
            // Connect to WebSocket server
            socket = new Socket("localhost", 8080);
            out = socket.getOutputStream();
            in = socket.getInputStream();
            
            // Perform WebSocket handshake
            String key = Base64.getEncoder().encodeToString(
                ("client" + System.currentTimeMillis()).getBytes()
            );
            
            String handshake = "GET / HTTP/1.1\r\n" +
                             "Host: localhost:8080\r\n" +
                             "Upgrade: websocket\r\n" +
                             "Connection: Upgrade\r\n" +
                             "Sec-WebSocket-Key: " + key + "\r\n" +
                             "Sec-WebSocket-Version: 13\r\n\r\n";
            
            out.write(handshake.getBytes());
            out.flush();
            
            // Read handshake response
            BufferedReader reader = new BufferedReader(new InputStreamReader(in));
            String line;
            while (!(line = reader.readLine()).isEmpty()) {
                // Skip headers
            }
            
            System.out.println("Connected to WebSocket Server");
            
            // Call sayHello
            String response = callRemote("HELLO", "Alice");
            System.out.println("Response from server: " + response);
            
            // Call add
            String sum = callRemote("ADD", "5,3");
            System.out.println("5 + 3 = " + sum);
            
            // Send messages to server
            Scanner scanner = new Scanner(System.in);
            System.out.println("\n--- Send Messages to Server ---");
            System.out.println("Type your messages (type 'quit' to stop):");
            
            while (true) {
                System.out.print("> ");
                String message = scanner.nextLine();
                
                if (message.equalsIgnoreCase("quit")) {
                    break;
                }
                
                // Send message to server
                String result = callRemote("SEND", message);
                System.out.println(result);
            }
            
            // Retrieve all messages from server
            System.out.println("\n--- All Messages on Server ---");
            String allMessages = callRemote("GETALL", "");
            
            if (allMessages.equals("No messages")) {
                System.out.println("No messages stored on server");
            } else {
                String[] msgArray = allMessages.split(";;");
                for (int i = 0; i < msgArray.length; i++) {
                    System.out.println((i + 1) + ". " + msgArray[i]);
                }
            }
            
            // Close connection
            socket.close();
            scanner.close();
            
        } catch (Exception e) {
            System.err.println("Client error: " + e.getMessage());
            e.printStackTrace();
        }
    }
    
    private static String callRemote(String method, String params) throws IOException {
        String request = params.isEmpty() ? method : method + "|" + params;
        sendMessage(request);
        return receiveMessage();
    }
    
    private static void sendMessage(String message) throws IOException {
        byte[] data = message.getBytes();
        Random random = new Random();
        byte[] mask = new byte[4];
        random.nextBytes(mask);
        
        out.write(0x81); // Text frame
        out.write(0x80 | data.length); // Masked
        out.write(mask);
        
        for (int i = 0; i < data.length; i++) {
            out.write(data[i] ^ mask[i % 4]);
        }
        
        out.flush();
    }
    
    private static String receiveMessage() throws IOException {
        int b = in.read();
        if (b == -1) return null;
        
        b = in.read();
        int length = b & 0x7F;
        
        byte[] data = new byte[length];
        in.read(data);
        
        return new String(data);
    }
}