【JavaEE初阶】 网络编程基础与Socket套接字

在Java中，网络编程基于java.net包，其中最常用的是Socket类和ServerSocket类。

ServerSocket示例代码：

import java.io.*;
import java.net.*;
 
public class SimpleServer {
    public static void main(String[] args) throws IOException {
        int port = 1234; // 选择一个端口
        try (ServerSocket serverSocket = new ServerSocket(port);
             Socket clientSocket = serverSocket.accept(); // 等待客户端连接
             PrintWriter writer = new PrintWriter(clientSocket.getOutputStream(), true);
             BufferedReader reader = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()))) {
 
            String message = "Hello from server!";
            writer.println(message); // 发送消息给客户端
 
            String response = reader.readLine(); // 读取客户端的响应
            System.out.println("Client says: " + response);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Socket示例代码：

import java.io.*;
import java.net.*;
 
public class SimpleClient {
    public static void main(String[] args) throws IOException {
        String host = "localhost"; // 服务器地址
        int port = 1234; // 服务器端口
        try (Socket socket = new Socket(host, port);
             PrintWriter writer = new PrintWriter(socket.getOutputStream(), true);
             BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()))) {
 
            String response = reader.readLine(); // 读取服务器的消息
            System.out.println("Server says: " + response);
 
            String message = "Hello from client!";
            writer.println(message); // 发送消息给服务器
        } catch (UnknownHostException e) {
            System.err.println("Don't know about host " + host);
        } catch (IOException e) {
            System.err.println("Couldn't get I/O for the connection to " + host);
        }
    }
}

以上代码展示了如何创建一个简单的服务器和客户端。服务器在特定端口上监听，客户端连接到服务器，然后双方通过PrintWriter和BufferedReader发送和接收文本消息。这是网络编程的基础，对于初学者来说，理解这些代码对于后续的网络编程学习非常重要。