#UDP编程

import socket

# 1. 创建UDP专用socket：AF_INET是IPv4，SOCK_DGRAM是UDP
server_sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

# 2. 绑定服务器地址（0.0.0.0表示监听所有网卡，这里先用127.0.0.1本地测试）
server_addr = ("127.0.0.1", 9999)
server_sock.bind(server_addr)
print(f"✅ UDP本地服务器已启动，监听地址：{server_addr[0]}:{server_addr[1]}")

try:
    while True:
        print("\n⏳ 等待接收客户端消息...")
        # 3. 接收数据：每次最多收1024字节，返回(数据二进制, 发送方元组)
        data, client_addr = server_sock.recvfrom(1024)
        
        print(f"📥 来自 {client_addr} 的消息：{data.decode('utf-8')}")
        
        # 4. 原路返回响应
        reply = f"📤 服务器收到了：{data.decode('utf-8')}"
        server_sock.sendto(reply.encode("utf-8"), client_addr)

except KeyboardInterrupt:
    print("\n🛑 用户手动停止服务器")
finally:
    server_sock.close()
    print("🔌 服务器socket已关闭")

import socket

# 1. 创建客户端socket（可以复用同一个，也不用bind）
client_sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

# 指定服务器地址
server_addr = ("127.0.0.1", 9999)

# 测试消息列表
test_msgs = ["你好呀UDP！", "Python编程真有意思", "试试最后一条消息"]

try:
    for msg in test_msgs:
        print(f"📤 发送消息：{msg}")
        client_sock.sendto(msg.encode("utf-8"), server_addr)
        
        # 2. 接收响应（同样限制1024字节）
        reply, _ = client_sock.recvfrom(1024)  # 这里服务器地址可以用_忽略
        print(f"📥 收到回复：{reply.decode('utf-8')}\n")

except Exception as e:
    print(f"❌ 出错了：{e}")
finally:
    client_sock.close()
    print("🔌 客户端socket已关闭")

import socket
import json

def run_json_udp_server():
    # 用with语句自动管理socket生命周期
    with socket.socket(socket.AF_INET, socket.SOCK_DGRAM) as sock:
        sock.bind(("0.0.0.0", 9999))
        sock.settimeout(5.0)  # 5秒没收到数据就触发超时异常
        print("✅ 优化版JSON UDP服务器已启动，支持结构化数据！")

        while True:
            try:
                data, client_addr = sock.recvfrom(1024)
                try:
                    # 尝试解析JSON
                    req_msg = json.loads(data.decode("utf-8"))
                    print(f"📥 来自 {client_addr} 的结构化请求：{req_msg}")

                    # 构造标准化响应
                    resp_msg = {"code": 200, "status": "success", "received_data": req_msg}
                    sock.sendto(json.dumps(resp_msg).encode("utf-8"), client_addr)

                except json.JSONDecodeError:
                    # JSON格式不对的错误
                    print(f"⚠️ 来自 {client_addr} 的消息不是有效JSON")
                    error_resp = {"code": 400, "status": "error", "msg": "Invalid JSON format"}
                    sock.sendto(json.dumps(error_resp).encode("utf-8"), client_addr)

            except socket.timeout:
                # 超时只打印日志，继续监听
                print("⏸️ 5秒无消息，继续监听...")
            except KeyboardInterrupt:
                # 用户Ctrl+C停止
                print("\n🛑 用户手动停止服务器")
                break
            except Exception as e:
                # 其他未知错误，直接退出
                print(f"❌ 服务器遇到未知错误：{e}")
                break

if __name__ == "__main__":
    run_json_udp_server()