Java实现tcp套接字编程实现聊天

### Java TCP Socket Programming Example for Chat Application For creating a simple chat application using Java, one needs to understand how client-server communication works over TCP. In this setup, the server listens for incoming connections from clients and handles messages sent by them. #### Server-Side Code Implementation Below is an example of setting up a basic server that accepts multiple clients: ```java import java.io.*; import java.net.ServerSocket; import java.net.Socket; public class ChatServer { public static void main(String[] args) throws IOException { int port = 12345; // Port number where server will listen try (ServerSocket serverSocket = new ServerSocket(port)) { System.out.println("Chat Server started on port " + port); while (true) { Socket socket = serverSocket.accept(); // Accepts incoming client requests // Handle each client request in separate thread ClientHandler handler = new ClientHandler(socket); Thread t = new Thread(handler); t.start(); } } catch (IOException e) { System.err.println("Could not start server"); e.printStackTrace(); } } private static class ClientHandler implements Runnable { private final Socket socket; public ClientHandler(Socket socket) { this.socket = socket; } @Override public void run() { try ( BufferedReader inputReader = new BufferedReader(new InputStreamReader(socket.getInputStream())); PrintWriter outputWriter = new PrintWriter(socket.getOutputStream(), true) ) { String message; while ((message = inputReader.readLine()) != null && !message.equalsIgnoreCase("bye")) { System.out.println("Received: " + message); outputWriter.println(message.toUpperCase()); // Echo back uppercase version if ("exit".equalsIgnoreCase(message.trim())) break; } } catch (IOException ex) { ex.printStackTrace(); } finally { try { socket.close(); } catch (IOException e) {} } } } } ``` This implementation sets up a `ChatServer` listening at specified port[^1]. Each time a client connects via `accept`, a new instance of `ClientHandler` runs as its own thread handling I/O operations independently without blocking others[^4]. #### Client-Side Code Implementation Here’s what the corresponding client-side looks like when connecting to such servers: ```java import java.io.*; import java.net.Socket; public class ChatClient { public static void main(String[] args) { String hostname = "localhost"; int port = 12345; try ( Socket socket = new Socket(hostname, port); BufferedReader userInput = new BufferedReader(new InputStreamReader(System.in)); BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())) ) { System.out.print("> "); String line; while((line=userInput.readLine())!=null){ writer.write(line+"\n");writer.flush(); if(line.equals("exit")){ break; } } }catch(Exception e){ e.printStackTrace(); } } } ``` In this snippet, after establishing connection through `new Socket(...)`, standard streams are wrapped around sockets' input/output channels allowing bidirectional data exchange.