java uuid to long,如何使用UUID生成唯一的Long

I have a requirement to generate unique Long ids for my database primary key column.

I thought i can use UUID.randomUUID().getMostSignificantBits() but sometimes its generating some negative long also which is problem for me.

Is it possible to generate only positive long from UUID ?There will be like billions of entries so i want that each generated key must be unique.

解决方案

Take a look at http://commons.apache.org/sandbox/commons-id//index.html

It has a LongGenerator that can give you exactly what you need.

In addition if you are using Hibernate then you can ask it to generate IDs for you (it has several algorithms you can choose from), in if not you can just take a look at their implementation for example http://grepcode.com/file/repo1.maven.org/maven2/hibernate/hibernate/2.1.8/net/sf/hibernate/id/TableHiLoGenerator.java#TableHiLoGenerator)