W7_staticmethod_classmethod_property_反射_exception_socket

w7_staticmethod_TryExcept_socket

• 94.第03章节-Python3.5-静态方法、类方法、属性方法
• 97.第06章节-Python3.5-深入讲解类的特殊成员方法__new__等
• 98.第07章节-Python3.5-反射详解1
• 100.第09章节-Python3.5-异常处理TryExcept
  • 异常语法
  • 自定义异常
• 101.第10章节-Python3.5-网络编程Socket介绍1
• 102.第11章节-Python3.5-网络编程Socket介绍2
  • socket_server
  • socket_client
• 103.基于udp的socket服务
• 145.黏包现象

94.第03章节-Python3.5-静态方法、类方法、属性方法

静态方法：只是看似归类管理，实际上在静态方法里访问不了类或实例中的任何属性
类方法：只能访问类变量，不能访问实例变量
属性方法：把一个方法变成一个静态属性

97.第06章节-Python3.5-深入讲解类的特殊成员方法__new__等

类的另一种构造：

def func(self):
    print("hello %s" % self.name)

def __init__(self,name,age):
    self.name = name
    self.age = age

Foo = type("Foo",(object,), {"talk":func , "__init__":__init__})
f = Foo("Chrn",22)
f.talk()

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98.第07章节-Python3.5-反射详解1

hasattr(obj.name_str) #判断一个对像obj里是否有对应的name_str字符串的方法
getattr(obj.name_str) #根据字符串去获取obj对象里的对应的方法的内存地址

class Dog(object):
    def __init__(self,name):
        self.name = name
    def eat(self,food):
        print("%s is eating %s" % (self.name, food))
d = Dog("no1_dog")
choice = input(">>:").strip()
if hasattr(d,choice):
    func = getattr(d,choice)
    func("baozi")
setattr(obj,"string",v) # is equivalent to ''obj.string = v''
delattr(obj,y)  # is equivalent to ''del obj.y''

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100.第09章节-Python3.5-异常处理TryExcept

异常语法

data = {}
list = [1,2]

try:
    data["name"]
    list[3]
    open("fdsafdf")
    a = 1
except KeyError as e:
    print("字典没有这个key", e)
except IndexError as e:
    print("列表没有这个索引",e)
except (KeyError,IndexError) as e:  #把多项合并的写法，多项异常执行同一操作
    print("出错了：", e)
except Exception as e:
    print("未知错误",e)
else:
    print("一切正常")
finally:
    print("不管正常与否，都得执行")


#python2.7的写法：中间使用逗号隔开
#except KeyError, e:

自定义异常

class Wuexcetion(Exception):
    def __init__(self,msg):
        self.msg = msg
    def __str__(self):
        return self.msg

# db_conn_e = Wuexcetion("test db connection exception")
# print(db_conn_e)

conn_status = 2
# conn_status = 1

try:
    if conn_status > 1:
        raise Wuexcetion("数据库没有连接上")
    else:
        pass
except Wuexcetion as e:
    print(e)

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101.第10章节-Python3.5-网络编程Socket介绍1

TCP：

socket:

refer:https://www.cnblogs.com/Eva-J/articles/8244551.html

102.第11章节-Python3.5-网络编程Socket介绍2

socket_server

import socket
server = socket.socket()
server.bind(('localhost',6969))
server.listen()
print("我要开始等电话了")
conn,add = server.accept()
print("电话打进来了")
data = conn.recv(1024)
print("recv:",data)
conn.send(data.upper())
conn.close()
server.close()

socket_client

import socket
client = socket.socket()
client.connect(('localhost',6969))
client.send(b"hello world")
data = client.recv(1024)
print("recv:",data)
client.close()

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103.基于udp的socket服务

udp_server.py

import socket
sk = socket.socket(type=socket.SOCK_DGRAM)
sk.bind(("127.0.0.1",6969))
while True:
    msg, addr = sk.recvfrom(1024)
    print(msg)
    info = input("server:")
    info = ("server:" + info).encode("utf-8")
    sk.sendto(info,addr)
sk.close()

udp_client1.py

import socket
sk = socket.socket(type=socket.SOCK_DGRAM)
ip_port = ("127.0.0.1",6969)
while True:
    info = input("client1:")
    info = ("client1:" + info).encode("utf-8")
    sk.sendto(info, ip_port)
    msg,add = sk.recvfrom(1024)
    print(msg)
sk.close()

udp_client2.py

import socket
sk = socket.socket(type=socket.SOCK_DGRAM)
ip_port = ("127.0.0.1",6969)
while True:
    info = input("client2:")
    info = ("client2:" + info).encode("utf-8")
    sk.sendto(info, ip_port)
    msg,add = sk.recvfrom(1024)
    print(msg)
sk.close()

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145.黏包现象

黏包现象只发生在tcp协议中：

1.从表面上看，黏包问题主要是因为发送方和接收方的缓存机制、tcp协议面向流通信的特点。
2.实际上，主要还是因为接收方不知道消息之间的界限，不知道一次性提取多少字节的数据所造成的
黏包成因：https://www.cnblogs.com/Eva-J/articles/8244551.html

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