代码收藏家技术教程 2022-07-20

Python 如何生成uuid

Universally Unique Identifier (UUID)，即通用唯一识别码，是一种软件建构的标准。它的目的在于让分布式系统中的所有元素，都能有唯一的辨识信息，而不需要中央控制端做辨识信息的制定。每个人都可以创建与其他人不冲突（重复）的UUID，因此常用作对某一东西的唯一标识。

UUID常用作数据库的主键。
UUID常用作一次计算任务的唯一标识。
Python uuid
Python中内置了一个名为uuid包来处理UUID的生成，使用起来非常方便，它提供了生成36位uuid的方法（32位加上4个’-'号作为间隔符，如果不需要间隔符可以手动去掉）。
Python的uuid包一共提供了4中生成UUID的方法：
uuid1()uuid3()uuid4()uuid5()
注：没有uuid2。
使用示例：
import uuid

print(uuid.uuid1())
print(uuid.uuid3(uuid.NAMESPACE_DNS, "test"))
print(uuid.uuid4()) # b983907d-ab25-4002-9dad-c37968936ba8
print(uuid.uuid5(uuid.NAMESPACE_DNS, "test"))

为了信息安全，uuid4之外的结果没有贴出来，读者可以本地自行试试。
注意：生成的uuid不是字符串类型，如果以字符串形式落库或者传递需要手动转换一下：
import uuid

print(type(uuid.uuid4()))
print(str(uuid.uuid4()))

四种生成uuid方法间的区别

官方文档见：https://docs.python.org/3/library/uuid.html?highlight=uuid#module-uuid

uuid1根据当前时间的时间戳加上电脑的mac地址生成，最后12位字符对应mac地址。因为是mac地址，所以本身具备唯一性。但是用这种方法生成uuid并分享泄露了自己的mac地址，因此不推荐使用。uuid3根据传入的namespace和一个由调用者指定字符串调用MD5算法生成。uuid4则是根据随机数生成的，因为不需要参数所以使用起来很方便，但需要注意的是，因为是随机数，所以极其小的概率下也可能会重复。uuid5同样根据传入的namespace和一个由调用者指定字符串生成uuid，如uuid3不同的是，它使用SHA1算法。
源码列在下面👇🏻：
def uuid1(node=None, clock_seq=None):
"""Generate a UUID from a host ID, sequence number, and the current time.
If 'node' is not given, getnode() is used to obtain the hardware
address. If 'clock_seq' is given, it is used as the sequence number;
otherwise a random 14-bit sequence number is chosen."""

# When the system provides a version-1 UUID generator, use it (but don't
# use UuidCreate here because its UUIDs don't conform to RFC 4122).
_load_system_functions()
if _generate_time_safe is not None and node is clock_seq is None:
uuid_time, safely_generated = _generate_time_safe()
try:
is_safe = SafeUUID(safely_generated)
except ValueError:
is_safe = SafeUUID.unknown
return UUID(bytes=uuid_time, is_safe=is_safe)

global _last_timestamp
import time
nanoseconds = int(time.time() * 1e9)
# 0x01b21dd213814000 is the number of 100-ns intervals between the
# UUID epoch 1582-10-15 00:00:00 and the Unix epoch 1970-01-01 00:00:00.
timestamp = int(nanoseconds/100) + 0x01b21dd213814000
if _last_timestamp is not None and timestamp <= _last_timestamp:
timestamp = _last_timestamp + 1
_last_timestamp = timestamp
if clock_seq is None:
import random
clock_seq = random.getrandbits(14) # instead of stable storage
time_low = timestamp & 0xffffffff
time_mid = (timestamp >> 32) & 0xffff
time_hi_version = (timestamp >> 48) & 0x0fff
clock_seq_low = clock_seq & 0xff
clock_seq_hi_variant = (clock_seq >> 8) & 0x3f
if node is None:
node = getnode()
return UUID(fields=(time_low, time_mid, time_hi_version,
clock_seq_hi_variant, clock_seq_low, node), version=1)

def uuid3(namespace, name):
"""Generate a UUID from the MD5 hash of a namespace UUID and a name."""
from hashlib import md5
hash = md5(namespace.bytes + bytes(name, "utf-8")).digest()
return UUID(bytes=hash[:16], version=3)

def uuid4():
"""Generate a random UUID."""
return UUID(bytes=os.urandom(16), version=4)

def uuid5(namespace, name):
"""Generate a UUID from the SHA-1 hash of a namespace UUID and a name."""
from hashlib import sha1
hash = sha1(namespace.bytes + bytes(name, "utf-8")).digest()
return UUID(bytes=hash[:16], version=5)

# The following standard UUIDs are for use with uuid3() or uuid5().

NAMESPACE_DNS = UUID('6ba7b810-9dad-11d1-80b4-00c04fd430c8')
NAMESPACE_URL = UUID('6ba7b811-9dad-11d1-80b4-00c04fd430c8')
NAMESPACE_OID = UUID('6ba7b812-9dad-11d1-80b4-00c04fd430c8')
NAMESPACE_X500 = UUID('6ba7b814-9dad-11d1-80b4-00c04fd430c8')

def uuid1(node=None, clock_seq=None):
"""Generate a UUID from a host ID, sequence number, and the current time.
If 'node' is not given, getnode() is used to obtain the hardware
address. If 'clock_seq' is given, it is used as the sequence number;
otherwise a random 14-bit sequence number is chosen."""