使用套接字将消息从Java客户端发送到Python服务器，反之亦然

基础概念

套接字（Socket）是网络通信的基本构建块，它允许不同计算机上的应用程序通过互联网进行通信。套接字分为两种主要类型：流套接字（用于TCP通信）和数据报套接字（用于UDP通信）。TCP是一种面向连接的协议，提供可靠的数据传输；而UDP是一种无连接协议，传输速度更快但不保证数据的可靠性。

类型

流套接字（TCP）：提供有序、可靠、基于连接的数据传输。
数据报套接字（UDP）：提供无连接、不可靠的数据传输，但速度更快。

应用场景

Web服务器和客户端：HTTP和HTTPS协议基于TCP套接字。
即时通讯：如聊天应用，可能使用UDP以提高速度。
文件传输：如FTP，通常使用TCP确保数据完整性。

Java客户端发送消息到Python服务器示例

Java客户端代码

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

public class JavaClient {
    public static void main(String[] args) {
        String hostName = "127.0.0.1";
        int portNumber = 12345;

        try (Socket socket = new Socket(hostName, portNumber);
             PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
             BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
             BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in))) {

            System.out.print("Type message to send: ");
            String userInput = stdIn.readLine();
            out.println(userInput);

            System.out.println("Server response: " + in.readLine());
        } catch (UnknownHostException e) {
            System.err.println("Don't know about host " + hostName);
            System.exit(1);
        } catch (IOException e) {
            System.err.println("Couldn't get I/O for the connection to " + hostName);
            System.exit(1);
        }
    }
}

Python服务器代码

import socket

host = '127.0.0.1'
port = 12345

with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
    s.bind((host, port))
    s.listen()
    conn, addr = s.accept()
    with conn:
        print('Connected by', addr)
        while True:
            data = conn.recv(1024)
            if not data:
                break
            print(f"Received message: {data.decode()}")
            conn.sendall(data)

Python服务器发送消息到Java客户端示例

Python服务器代码（修改后）

import socket

host = '127.0.0.1'
port = 12345

with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
    s.bind((host, port))
    s.listen()
    conn, addr = s.accept()
    with conn:
        print('Connected by', addr)
        while True:
            data = conn.recv(1024)
            if not data:
                break
            print(f"Received message: {data.decode()}")
            response = "Hello from Python server!"
            conn.sendall(response.encode())

Java客户端代码（修改后）

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

public class JavaClient {
    public static void main(String[] args) {
        String hostName = "127.0.0.1";
        int portNumber = 12345;

        try (Socket socket = new Socket(hostName, portNumber);
             PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
             BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
             BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in))) {

            System.out.print("Type message to send: ");
            String userInput = stdIn.readLine();
            out.println(userInput);

            System.out.println("Server response: " + in.readLine());
        } catch (UnknownHostException e) {
            System.err.println("Don't know about host " + hostName);
            System.exit(1);
        } catch (IOException e) {
            System.err.println("Couldn't get I/O for the connection to " + hostName);
            System.exit(1);
        }
    }
}