python3.5 异步协议

Question

我想搭建一个聊天demo，但是我收不到服务器端发来的东西，除了第一次启动，谁知道为什么？来自 https://docs.python.org/3.4/library/asyncio-protocol.html#tcp-echo-client-protocol

的代码

Server.py

import asyncio

class EchoServerClientProtocol(asyncio.Protocol):
    def connection_made(self, transport):
        peername = transport.get_extra_info('peername')
        print('Connection from {}'.format(peername))
        self.transport = transport

    def data_received(self, data):
        message = data.decode()
        print('Data received: {!r}'.format(message))
        print('Send: {!r}'.format(message))
        self.transport.write(data)


loop = asyncio.get_event_loop()
# Each client connection will create a new protocol instance
coro = loop.create_server(EchoServerClientProtocol, '127.0.0.1', 8888)
server = loop.run_until_complete(coro)

# Serve requests until Ctrl+C is pressed
print('Serving on {}'.format(server.sockets[0].getsockname()))
try:
    loop.run_forever()
except KeyboardInterrupt:
    pass

# Close the server
server.close()
loop.run_until_complete(server.wait_closed())
loop.close()

Client.py

class EchoClientProtocol(asyncio.Protocol):
    def __init__(self, message, loop):
        self.message = message
        self.loop = loop
        self.transport = None

    def connection_made(self, transport):
        self.transport = transport

        transport.write(self.message.encode())
        print('Data sent: {!r}'.format(self.message))

        # while 1:
        #     message=input('please input the message:')
        #     transport.write(message.encode())
        #     print('Data sent: {!r}'.format(message))

    def data_received(self, data):
        # print('data_received')
        print('Data received: {!r}'.format(data.decode()))
        while 1:
            message = input('please input the message:')
            self.transport.write(message.encode())
            print('Data sent: {!r}'.format(message))

    def connection_lost(self, exc):
        print('The server closed the connection')
        print('Stop the event loop')
        self.loop.stop()

loop = asyncio.get_event_loop()
message = 'Hello World!'
coro = loop.create_connection(lambda: EchoClientProtocol(message, loop),
                              '127.0.0.1', 8888)
loop.run_until_complete(coro)
loop.run_forever()
loop.close()

结果显示：无法显示 'Data received: '#####' 比如 'def data_received(self, data)' 只用了一次有人有解决办法吗？ [结果][1] [1]: https://i.stack.imgur.com/IoqA9.png

Answer 1

您从 EchoClientProtocol.data_received() 创建了所谓的阻塞函数。只有当事件循环可以处理它但阻止功能阻止它时，来自服务器的每个传递的消息才能传递到 EchoClientProtocol.data_received()。

这个代码

while 1: # More Pythonic way is While True
    message = input('please input the message:')
    self.transport.write(message.encode())

从用户获取消息并将其发送到服务器，直到这一刻一切都很好。在下一步中，它开始另一个循环，但代码永远不会进入事件循环（因此无法处理传入的消息）。

您可以像这样编辑客户端代码：

    def data_received(self, data):
        print('Data received: {!r}'.format(data.decode()))
        message = input('please input the message:')
        self.transport.write(message.encode())

当您从服务器接收到 Hello World! 时，首先调用客户端中的 data_received（它是从 connection_made 发送的 Hello World!）。现在处理如下：

它打印收到的消息（在第一次调用时是 Hello World!）
收到用户的新消息
发送到服务器
函数returns并将控制权交给事件循环。
服务器收到新消息并将其发送回客户端
客户端调用的事件循环data_received
转到步骤 1

python3.5 异步协议

python3.5 asyncio Protocol

tcp

python-3.x

python-3.4

python-asyncio