如何生成唯一ID [英] How to generate unique id

问题描述

如何在同时运行的两个JVM之间生成唯一的ID?我认为 UUID uuid = UUID.randomUUID(); 或 UID uid = new UID(); 是不够的.

How can we generate unique id's between two JVMs running at the same time? I think UUID uuid = UUID.randomUUID(); or UID uid = new UID(); is not enough.

推荐答案

请参见 UUID 文档，您可以通过该链接找到 rfc4122解释如何生成UUID.最后48位与您的问题有关，空间唯一节点标识符确认此值将是 Universally Unique IDentifier .

See UUID docs, you can follow the link to find the rfc4122 explaining how the UUID will be generated. The last 48 bits are concerning your question, the spacial unique node identifier confirming that this value will be a Universally Unique IDentifier.

4.1.2.  Layout and Byte Order

   To minimize confusion about bit assignments within octets, the UUID
   record definition is defined only in terms of fields that are
   integral numbers of octets.  The fields are presented with the most
   significant one first.

   Field                  Data Type     Octet  Note
                                        #

   time_low               unsigned 32   0-3    The low field of the
                          bit integer          timestamp

   time_mid               unsigned 16   4-5    The middle field of the
                          bit integer          timestamp

   time_hi_and_version    unsigned 16   6-7    The high field of the
                          bit integer          timestamp multiplexed
                                               with the version number


   clock_seq_hi_and_rese  unsigned 8    8      The high field of the
   rved                   bit integer          clock sequence
                                               multiplexed with the
                                               variant

   clock_seq_low          unsigned 8    9      The low field of the
                          bit integer          clock sequence

   node                   unsigned 48   10-15  The spatially unique
                          bit integer          node identifier

我能看到的唯一风险来自该部分

The only risk I can see come from that part

UUID是一个在空间和时间上都是唯一的标识符，关于所有UUID的空间.由于UUID是固定的大小并包含一个时间字段，值可能会滚动

A UUID is an identifier that is unique across both space and time, with respect to the space of all UUIDs. Since a UUID is a fixed size and contains a time field, it is possible for values to rollover

但这需要运行很长时间才能出现.因此，对于您当前的解决方案，我不会太担心.

But this would need to run for a long time before it come to you. So, I would not be worried to much with you current solution.

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