python3中bytes、hex和字符串相互转换

1、字符串转bytes

a = 'abcd'
a1 = bytes(a,encoding('utf-8'))

2、bytes转字符串

a = b'abcd'
a1 = bytes.decode(a , encoding('utf-8'))

3、16进制字符串转bytes

a='01 02 03 04 05 06'
a1 = a.replace(' ' ,'')
a2 = bytes,fromhex(a1)

4、bytes转16进制字符串

"".join(['%02X ' % b for b in bs])

5、byte和int相互转换

b = b'\x12\x34'
n = int.from_bytes(b,byteorder='big',signed=False)
#b'\x12\x34'->4660

n = 4660
b = n.to_bytes(length=2,byteorder='big',signed=False)
#4660->b'\x12\x34'

6、字节数组bytearray

1)  可变的字节序列，相当于bytes的可变版本

2)  创建bytearray对象的方法规则

bytearray()
bytearray(整数n)
bytearray(整型可迭代对象)
bytearray(b'字符串')
bytearray(字符串, encoding='utf-8')

　　示例：

>>> bytearray()
bytearray(b'')

>>> bytearray([1,2,3])
bytearray(b'\x01\x02\x03')

>>> bytearray(["a","b","c"])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: an integer is required

>>> bytearray(3)
bytearray(b'\x00\x00\x00')

>>> bytearray("abc",encoding="utf-8")
bytearray(b'abc')

>>> bytearray("abc")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: string argument without an encoding