JPA：在单个字段中存储整数列表 [英] JPA: Store a list of integers in a single field

问题描述

是否可以在标准JPA 2的相应实体表的单个字段中存储整数列表？

Is it possible to store a list of integers in a single field of the respective entity table with standard JPA 2?

类似于：

 @Entity
 @Table(name="tbl_myentities")
 public class MyEntity {

   @ElementaryCollection
   @Column(name="vals") // in table tbl_myentities
   private List<Integer> vals;

谢谢

推荐答案

无法在单个字段中存储多个值。是什么原因将它们存储在一个字段中？

It is not possible to store multiple values in a single field. Whats the reason behind storing them in a single field?

一种方法可能是使用String类型的字段并在逗号分隔列表中添加所有整数并加入/在getter和setter中爆炸：

A way could be to use a field of type String and add all integers there in a comma separated list and join/explode in getters and setters:

private String vals;

public setVals(int vals[])
{
     // this.vals = Iterate vals[] and create a comma separated string
}

public int[] getVals()
{
    // vals.split(",") to get a list of Strings, then typecast/parse them to ints before returning
}

使用 @ElementCollection 注释和 @CollectionTable 控制映射需要一个单独的表来存储值。

Using the @ElementCollection annotation and @CollectionTable to control the mappings requires a separate table to store the values in.

@ElementCollection
private Collection<Integer> integers;

详细了解 http://en.wikibooks.org/wiki/Java_Persistence/ElementCollection

相似的问题这里 JPA @ElementCollection注释是否总是生成一个注释多对多关系？

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