Socketserver详解

Python3中的SocketServer

　　socket并不能多并发，只能支持一个用户，socketserver 简化了编写网络服务程序的任务，socketserver是socket的在封装。socketserver在python2中为SocketServer,在python3种取消了首字母大写，改名为socketserver。socketserver中包含了两种类，一种为服务类（server class），一种为请求处理类（request handle class）。前者提供了许多方法：像绑定，监听，运行…… （也就是建立连接的过程）后者则专注于如何处理用户所发送的数据（也就是事务逻辑）。一般情况下，所有的服务，都是先建立连接，也就是建立一个服务类的实例，然后开始处理用户请求，也就是建立一个请求处理类的实例。

socketserver一共有这么几种类型：

1. class socketserver.TCPServer(server_address, RequestHandlerClass, bind_and_activate=True)

2. class socketserver.UDPServer(server_address, RequestHandlerClass, bind_and_activate=True)

3. class socketserver.UnixStreamServer(server_address, RequestHandlerClass, bind_and_activate=True)

4. class socketserver.UnixDatagramServer(server_address, RequestHandlerClass,bind_and_activate=True)

继承关系图：

+------------+

| BaseServer |

+------------+
|
v
+-----------+ +------------------+
| TCPServer |------->| UnixStreamServer |
+-----------+ +------------------+
|
v
+-----------+ +--------------------+
| UDPServer |------->| UnixDatagramServer |

+-----------+ +--------------------+

如何创建一个socketserver ：

First, you must create a request handler class by subclassing the BaseRequestHandlerclass and overriding its handle() method; this method will process incoming requests. 　　
Second, you must instantiate one of the server classes, passing it the server’s address and the request handler class.
Then call the handle_request() orserve_forever() method of the server object to process one or many requests.
Finally, call server_close() to close the socket.

　　1. 创建一个请求处理的类，并且这个类要继承 BaseRequestHandlerclass ，并且还要重写父类里handle()方法；

注释:为什么要重写handle方法时加上while循环

handle方法默认结束后断开链接继续监听

　　2. 你必须实例化 TCPServer，并且传递server IP和你上面创建的请求处理类，给这个TCPServer；

　　3. server.handle_requese()#只处理一个请求，server.server_forever()处理多个一个请求，永远执行

　　4. 关闭连接server_close()

import socketserver
class MyServer(socketserver.BaseRequestHandler):
    def handle(self):
        # 创建一个链接,继承于socketserver中的BaseRequestHandler类
        conn = self.request
        # 发送登录提示
        conn.sendall(b"Welcome to login...")
        print("Client connect...")
        while True:
            print("Waitting for recving message...")
            # 接收消息
            message = conn.recv(1024)
            print(message.decode('utf-8'))
            # 收到exit就退出
            if message == "exit":
                break
            # 回复消息
            data = input("Reply message:")
            # 发送消息
            conn.sendall(data.encode('utf-8'))
if __name__ == "__main__":
  　# 实例化
    server = socketserver.ThreadingTCPServer(('127.0.0.1', 999, ), MyServer)
    # 调用serve_forever方法
    server.serve_forever()
'''
def serve_forever(self, poll_interval=0.5):
    """
    Handle one request at a time until shutdown.
    Polls for shutdown every poll_interval seconds. Ignores
    self.timeout. If you need to do periodic tasks, do them in
    another thread.
    """
'''
multi_socketserver_client.py

# 就是一个简单的TCP客户端
import socket
sock = socket.socket()
# 连接服务端
sock.connect(('127.0.0.1', 999, ))
login = sock.recv(1024)
print(login.decode('utf-8'))
while True:
    message = input("Please input the message:").strip()
    if message == "exit":
        sock.sendall(b'exit')
        break
    else:
        sock.sendall(message.encode('utf-8'))
        print("Waitting for recving message...")
        data = sock.recv(1024)
        print(data.decode('utf-8'))
sock.close()