str bytes如何转换

str        使用encode方法转换为bytes(爬虫的得到的响应以二进制的方式传送)

In [9]: a = "你好"                                                              

In [10]: type(a)                                                                
Out[10]: str

In [11]: b = a.encode()                                                         

In [12]: b                                                                      
Out[12]: b'\xe4\xbd\xa0\xe5\xa5\xbd'

In [13]: type(b)                                                                
Out[13]: bytes

bytes     通过decode转化为 str

In [12]: b                                                                      
Out[12]: b'\xe4\xbd\xa0\xe5\xa5\xbd'

In [13]: type(b)                                                                
Out[13]: bytes

In [14]: c = b.decode()                                                         

In [15]: c                                                                      
Out[15]: '你好'

In [16]: type(c)                                                                
Out[16]: str

默认方式都以utf-8的方式编解码。其编解码的方式必须一样，否则会出现乱码

In [17]: a = "你好"                                                             

In [18]: b = a.encode("gbk")                                                    

In [19]: b.decode()                                                             
---------------------------------------------------------------------------
UnicodeDecodeError                        Traceback (most recent call last)
<ipython-input-19-4169e64150f6> in <module>
----> 1 b.decode()

UnicodeDecodeError: 'utf-8' codec can't decode byte 0xc4 in position 0: invalid continuation byte

In [20]: b.decode("gbk")                                                        
Out[20]: '你好'