• uuid —- UUID objects according to RFC 4122
    • 示例

    uuid —- UUID objects according to RFC 4122

    Source code:Lib/uuid.py

    This module provides immutable UUID objects (the UUID class)and the functions uuid1(), uuid3(), uuid4(), uuid5() forgenerating version 1, 3, 4, and 5 UUIDs as specified in RFC 4122.

    If all you want is a unique ID, you should probably call uuid1() oruuid4(). Note that uuid1() may compromise privacy since it createsa UUID containing the computer's network address. uuid4() creates arandom UUID.

    Depending on support from the underlying platform, uuid1() may or maynot return a "safe" UUID. A safe UUID is one which is generated usingsynchronization methods that ensure no two processes can obtain the sameUUID. All instances of UUID have an is_safe attributewhich relays any information about the UUID's safety, using this enumeration:

    • class uuid.SafeUUID

    3.7 新版功能.

    • safe

    • The UUID was generated by the platform in a multiprocessing-safe way.

    • unsafe

    • The UUID was not generated in a multiprocessing-safe way.

    • unknown

    • The platform does not provide information on whether the UUID wasgenerated safely or not.
    • class uuid.UUID(hex=None, bytes=None, bytes_le=None, fields=None, int=None, version=None, *, is_safe=SafeUUID.unknown)
    • Create a UUID from either a string of 32 hexadecimal digits, a string of 16bytes in big-endian order as the bytes argument, a string of 16 bytes inlittle-endian order as the bytes_le argument, a tuple of six integers(32-bit time_low, 16-bit time_mid, 16-bit time_hi_version,8-bit clock_seq_hi_variant, 8-bit clock_seq_low, 48-bit node) as thefields argument, or a single 128-bit integer as the int argument.When a string of hex digits is given, curly braces, hyphens,and a URN prefix are all optional. For example, theseexpressions all yield the same UUID:
    1. UUID('{12345678-1234-5678-1234-567812345678}')
    2. UUID('12345678123456781234567812345678')
    3. UUID('urn:uuid:12345678-1234-5678-1234-567812345678')
    4. UUID(bytes=b'\x12\x34\x56\x78'*4)
    5. UUID(bytes_le=b'\x78\x56\x34\x12\x34\x12\x78\x56' +
    6.               b'\x12\x34\x56\x78\x12\x34\x56\x78')
    7. UUID(fields=(0x12345678, 0x1234, 0x5678, 0x12, 0x34, 0x567812345678))
    8. UUID(int=0x12345678123456781234567812345678)

    Exactly one of hex, bytes, bytes_le, fields, or int must be given.The version argument is optional; if given, the resulting UUID will have itsvariant and version number set according to RFC 4122, overriding bits in thegiven hex, bytes, bytes_le, fields, or int.

    Comparison of UUID objects are made by way of comparing theirUUID.int attributes. Comparison with a non-UUID objectraises a TypeError.

    str(uuid) returns a string in the form12345678-1234-5678-1234-567812345678 where the 32 hexadecimal digitsrepresent the UUID.

    UUID instances have these read-only attributes:

    • UUID.bytes

    • The UUID as a 16-byte string (containing the six integer fields in big-endianbyte order).

    • UUID.bytes_le

    • The UUID as a 16-byte string (with time_low, time_mid, and _time_hi_version_in little-endian byte order).

    • UUID.fields

    • 以元组形式存放的UUID的6个整数域，有六个单独的属性和两个派生属性：

    域

    意义

    time_low

    UUID的前32位

    time_mid

    接前一域的16位

    time_hi_version

    接前一域的16位

    clock_seq_hi_variant

    接前一域的8位

    clock_seq_low

    接前一域的8位

    node

    UUID的最后48位

    time

    UUID的总长60位的时间戳

    clock_seq

    14位的序列号

    • UUID.hex

    • The UUID as a 32-character hexadecimal string.

    • UUID.int

    • The UUID as a 128-bit integer.

    • UUID.urn

    • The UUID as a URN as specified in RFC 4122.

    • UUID.variant

    • The UUID variant, which determines the internal layout of the UUID. This will beone of the constants RESERVED_NCS, RFC_4122,RESERVED_MICROSOFT, or RESERVED_FUTURE.

    • UUID.version

    • The UUID version number (1 through 5, meaningful only when the variant isRFC_4122).

    • UUID.is_safe

    • An enumeration of SafeUUID which indicates whether the platformgenerated the UUID in a multiprocessing-safe way.

    3.7 新版功能.

    The uuid module defines the following functions:

    • uuid.getnode()
    • Get the hardware address as a 48-bit positive integer. The first time thisruns, it may launch a separate program, which could be quite slow. If allattempts to obtain the hardware address fail, we choose a random 48-bitnumber with the multicast bit (least significant bit of the first octet)set to 1 as recommended in RFC 4122. "Hardware address" means the MACaddress of a network interface. On a machine with multiple networkinterfaces, universally administered MAC addresses (i.e. where the secondleast significant bit of the first octet is unset) will be preferred overlocally administered MAC addresses, but with no other ordering guarantees.

    在 3.7 版更改: Universally administered MAC addresses are preferred over locallyadministered MAC addresses, since the former are guaranteed to beglobally unique, while the latter are not.

    • uuid.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 random14-bit sequence number is chosen.

    • uuid.uuid3(namespace, name)

    • Generate a UUID based on the MD5 hash of a namespace identifier (which is aUUID) and a name (which is a string).

    • uuid.uuid4()

    • Generate a random UUID.

    • uuid.uuid5(namespace, name)

    • Generate a UUID based on the SHA-1 hash of a namespace identifier (which is aUUID) and a name (which is a string).

    The uuid module defines the following namespace identifiers for use withuuid3() or uuid5().

    • uuid.NAMESPACE_DNS

    • When this namespace is specified, the name string is a fully-qualified domainname.

    • uuid.NAMESPACE_URL

    • When this namespace is specified, the name string is a URL.

    • uuid.NAMESPACE_OID

    • When this namespace is specified, the name string is an ISO OID.

    • uuid.NAMESPACE_X500

    • When this namespace is specified, the name string is an X.500 DN in DER or atext output format.

    The uuid module defines the following constants for the possible valuesof the variant attribute:

    • uuid.RESERVED_NCS

    • Reserved for NCS compatibility.

    • uuid.RFC_4122

    • Specifies the UUID layout given in RFC 4122.

    • uuid.RESERVED_MICROSOFT

    • Reserved for Microsoft compatibility.

    • uuid.RESERVED_FUTURE

    • Reserved for future definition.

    参见

    • RFC 4122 - A Universally Unique IDentifier (UUID) URN Namespace
    • This specification defines a Uniform Resource Name namespace for UUIDs, theinternal format of UUIDs, and methods of generating UUIDs.

    示例

    Here are some examples of typical usage of the uuid module:

    1. >>> import uuid
    2.  
    3. >>> # make a UUID based on the host ID and current time
    4. >>> uuid.uuid1()
    5. UUID('a8098c1a-f86e-11da-bd1a-00112444be1e')
    6.  
    7. >>> # make a UUID using an MD5 hash of a namespace UUID and a name
    8. >>> uuid.uuid3(uuid.NAMESPACE_DNS, 'python.org')
    9. UUID('6fa459ea-ee8a-3ca4-894e-db77e160355e')
    10.  
    11. >>> # make a random UUID
    12. >>> uuid.uuid4()
    13. UUID('16fd2706-8baf-433b-82eb-8c7fada847da')
    14.  
    15. >>> # make a UUID using a SHA-1 hash of a namespace UUID and a name
    16. >>> uuid.uuid5(uuid.NAMESPACE_DNS, 'python.org')
    17. UUID('886313e1-3b8a-5372-9b90-0c9aee199e5d')
    18.  
    19. >>> # make a UUID from a string of hex digits (braces and hyphens ignored)
    20. >>> x = uuid.UUID('{00010203-0405-0607-0809-0a0b0c0d0e0f}')
    21.  
    22. >>> # convert a UUID to a string of hex digits in standard form
    23. >>> str(x)
    24. '00010203-0405-0607-0809-0a0b0c0d0e0f'
    25.  
    26. >>> # get the raw 16 bytes of the UUID
    27. >>> x.bytes
    28. b'\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f'
    29.  
    30. >>> # make a UUID from a 16-byte string
    31. >>> uuid.UUID(bytes=x.bytes)
    32. UUID('00010203-0405-0607-0809-0a0b0c0d0e0f')