java Java在内存中的SQL表之类的数据结构
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Java in memory SQL Table like data structure
提问by Adam Gent
Several times I have wanted a data structure that is similar to a SQL Table where you can select on various fields and multiple fields. Similar to an in memory SQL implementation except that I don't want to store that many objects in the data structure.
有几次我想要一个类似于 SQL 表的数据结构，您可以在其中选择各种字段和多个字段。类似于内存中的 SQL 实现，只是我不想在数据结构中存储那么多对象。
I also require the object to be serializable through standard Java means.
我还要求对象可以通过标准 Java 方式进行序列化。
I have done this before with multiple hash tables or custom hash keys but it ended up being a lot of code and very specific the problem.
我之前使用多个哈希表或自定义哈希键完成了此操作，但最终是大量代码并且问题非常具体。
I have also used Groovy with its closure ability and gpath to help but I don't always have it available (different projects).
我还使用 Groovy 的关闭功能和 gpath 来提供帮助，但我并不总是可用（不同的项目）。
EDIT: I think my problem is more of an object traversal/selection problem Here are some interesting projects:
编辑：我认为我的问题更像是一个对象遍历/选择问题这里有一些有趣的项目：
- http://josql.sourceforge.net/
- http://homepages.mcs.vuw.ac.nz/~djp/JQL/
- http://today.java.net/pub/a/today/2006/08/03/java-object-querying-using-jxpath.html
- http://code.google.com/p/lambdaj/(I used this in the past and it was.... slow...)
- http://jedi.codehaus.org/Jedi
- http://josql.sourceforge.net/
- http://homepages.mcs.vuw.ac.nz/~djp/JQL/
- http://today.java.net/pub/a/today/2006/08/03/java-object-querying-using-jxpath.html
- http://code.google.com/p/lambdaj/（我过去使用过它，但它......很慢......）
- http://jedi.codehaus.org/绝地武士
However the downside to most of these projects is that they are much slower than accessing the objects directly (non reflection getter/setter) and definitely slower than an index (hash).
然而，大多数这些项目的缺点是它们比直接访问对象（非反射 getter/setter）慢得多，而且绝对比索引（哈希）慢。
回答by Alex Weinstein
What concerns you about using in-memory SQL storage for these purposes? You'd save a ton of development time; performance overhead is really insignificant. You risk much more by trying to implement this yourself.
出于这些目的使用内存中的 SQL 存储有什么顾虑？您将节省大量的开发时间；性能开销真的微不足道。尝试自己实现它会冒更多的风险。
