java代码如何实现基于 TCP 的通信 java代码网络协议的应用技巧​

java.net

ServerSocket

Socket

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

public class SimpleEchoServer {
    public static void main(String[] args) {
        int port = 8080; // 服务器监听端口
        try (ServerSocket serverSocket = new ServerSocket(port)) {
            System.out.println("服务器启动，正在监听端口 " + port + "...");

            // 服务器通常需要处理多个客户端连接，这里用一个简单的循环模拟
            // 实际应用中，每个客户端连接通常会在单独的线程中处理
            while (true) {
                Socket clientSocket = serverSocket.accept(); // 阻塞，直到有客户端连接
                System.out.println("新客户端连接来自: " + clientSocket.getInetAddress().getHostAddress());

                // 为每个客户端连接创建一个新线程来处理，避免阻塞主线程
                new Thread(() -> {
                    try (
                        // 使用try-with-resources确保流自动关闭
                        PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);
                        BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()))
                    ) {
                        String inputLine;
                        while ((inputLine = in.readLine()) != null) {
                            System.out.println("收到客户端消息: " + inputLine);
                            out.println("服务器回应: " + inputLine); // 回显给客户端
                            if ("bye".equalsIgnoreCase(inputLine)) {
                                break; // 客户端发送"bye"则断开连接
                            }
                        }
                    } catch (IOException e) {
                        System.err.println("处理客户端连接时发生错误: " + e.getMessage());
                    } finally {
                        try {
                            clientSocket.close(); // 确保客户端Socket关闭
                            System.out.println("客户端连接已关闭: " + clientSocket.getInetAddress().getHostAddress());
                        } catch (IOException e) {
                            System.err.println("关闭客户端Socket失败: " + e.getMessage());
                        }
                    }
                }).start();
            }
        } catch (IOException e) {
            System.err.println("服务器启动或运行失败: " + e.getMessage());
        }
    }
}

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

public class SimpleEchoClient {
    public static void main(String[] args) {
        String hostName = "localhost"; // 服务器地址
        int port = 8080; // 服务器端口

        try (
            Socket socket = new Socket(hostName, port); // 尝试连接服务器
            PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
            BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            Scanner scanner = new Scanner(System.in) // 用于从控制台读取用户输入
        ) {
            System.out.println("已连接到服务器 " + hostName + ":" + port);
            String userInput;
            while (true) {
                System.out.print("请输入消息 (输入 'bye' 退出): ");
                userInput = scanner.nextLine(); // 读取用户输入

                out.println(userInput); // 发送消息到服务器

                String serverResponse = in.readLine(); // 读取服务器响应
                System.out.println("服务器回应: " + serverResponse);

                if ("bye".equalsIgnoreCase(userInput)) {
                    break; // 用户输入"bye"则退出
                }
            }
        } catch (UnknownHostException e) {
            System.err.println("无法识别主机: " + hostName);
            System.exit(1);
        } catch (IOException e) {
            System.err.println("无法获取I/O连接到 " + hostName + ":" + port + ": " + e.getMessage());
            System.exit(1);
        }
    }
}

BufferedReader

PrintWriter

try-catch-finally

IOException

try-catch

socket.accept()

in.readLine()

out.println()

Socket

InputStream

OutputStream

try

AutoCloseable

socket.accept()

socket.read()

socket.setSoTimeout(milliseconds)

socket.connect(socketAddress, timeout)

SocketTimeoutException

in.readLine()

null

SocketException

java.util.concurrent.Executors

FixedThreadPool

CachedThreadPool

Selector

Selector

SSLSocket

SSLServerSocket

Socket

ServerSocket