javax.persistence.metamodel.Map和java.util.Map之间有什么区别？ [英] What is the difference between javax.persistence.metamodel.Map and java.util.Map?

问题描述

我正在尝试在GAE中编写一个JDO注释类，并且要保留一张地图。该地图应该是一个实体字段，它是由Date对其进行散列的实体集合。 （我甚至不确定这是否正确）。

I am trying to write a JDO annotated class in GAE and I want to persist a map. The map is supposed to be an entity field that is a collection of entities hashed by Date. (I am not even sure if this is the right approach).

Eclipse的自动完成为我提供了javax.persistence.metamodel.Map和java.util.Map。这两者有什么区别？前者的例子是什么？

Eclipse's auto-complete provides me with javax.persistence.metamodel.Map and java.util.Map. What is the difference between these two? What is an example of the former?

推荐答案

其中一个是GAE支持的标准Java库中的类，其他是JPA API的一部分（您没有使用）。

One is a class from a standard Java library that is supported in GAE, and the other is part of the JPA API (that you're not using).

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