web-server单进程-非阻塞-长连接写法

本次的创建的web-server比上一次的发表有许多改进之处，首先是在进行多进程，多线程，协程的方案中我们选择了协程，但不同于一般的协程得是，我们是使用的非阻塞来完成多任务。此外对于长连接本次也用到了，可以让浏览器一次请求多个元素。

import socket
import re

def service_client(new_socket,request):

    request_lines = request.splitlines()
    print(request_lines)

    #GET /html HTTP/1.1
    ret = re.match(r"[^/]+(/[^ ]*)",request_lines[0])
    if ret:
        file_name = ret.group(1)
        print("*"*20,file_name)
        if file_name == "/":
            file_name = "/index.html"

    try:
        f = open("./html" + file_name, "rb")
    except:
    	#这个地方加入了Content-Length的header信息，告诉浏览器每次传输完成的会有多少个字节。
        err_msg = "-----file not found-----"
        response = "HTTP/1.1 404 NOT FOUND\r\n"
        response += "Content-Length:%d\r\n" % len(err_msg)
        response += "\r\n"
        response += "-----file not found-----"
        new_socket.send(response.encode("utf-8"))
    else:
        html_content = f.read()
        f.close()
        response_body = html_content
        response_header = "HTTP/1.1 200 ok\r\n"
        response_header += "Content-Length:%d\r\n" % len(html_content)
        response_header += "\r\n"
        response = response_header.encode("utf-8") + response_body
        new_socket.send(response)
	
	#这里是曾经的老式写法
        # response = "HTTP/1.1 200 ok\r\n"
        # response += "\r\n"
        # html_content = f.read()
        # new_socket.send(response.encode("utf-8"))
        # new_socket.send(html_content)
	
    # new_socket.close()  长连接的精髓在于不用立刻关闭连接重复使用
def main():
    tcp_socket = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
    tcp_socket.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1)
    tcp_socket.bind(("",7788))
    tcp_socket.listen(128)
    #设置socket非阻塞，因此下面对于accept当没有返回值会报错，需要对它进行异常捕获
    tcp_socket.setblocking(False)


    client_socket_list = []
    while True:
        try:
          #这个地方就是一个阻塞点
            new_socket,client_addr = tcp_socket.accept() 
        except Exception as ret:
            pass
        else:
            new_socket.setblocking(False)
            client_socket_list.append(new_socket)

        for client_socket in client_socket_list:
            try:
            	#这里是另一个阻塞点
                recv_data = client_socket.recv(1024).decode("utf-8")
            except Exception as ret:
                pass
            else:
            	#因为当有返回值时，存在返回空和返回数据的情况，于是需要下面的分开讨论。
                if recv_data:
                    service_client(client_socket,recv_data)
                else:
                    client_socket.close()
                    client_socket_list.remove(client_socket)

    tcp_socket.close()

if __name__ == "__main__":
    main()