问题:
假定,Parent类有一个Set属性,里面放的是Son。如果查询"from Parent",某个Parent哪怕一个Son都没有,那个Set属性不会为null,而是一个空集合。
这时候如果你Parent newP=new Parent();然后BeanUtils.copyPropertis(newP,origP);最后就会报hibernate异常"Found shared references to a collection"。
注:hibernate在什么时机发现"两个对象共享一个集合"的情况的?我这边的例子是在下一次查询时发现的。
原因:
BeanUtils.copyPropertis是浅拷贝,导致这两个对象引用的Set是同一个Set,这在hibernate中是不允许的,参见Hibernate reference第6章的"Two entities may not share a reference to the same collection instance"。
这种问题常见于复制对象时。
如何解决:newP.setSonSet(null);
还有人说原因可能是并发操作:http://www.blogjava.net/fastzch/archive/2006/12/22/89520.html
参考:
http://markmail.org/message/fszouomkeicjynw2
http://blog.csdn.net/programeyonger/archive/2008/01/31/2075304.aspx
http://www.iteye.com/topic/99505
http://www.blogjava.net/leekiang/archive/2008/10/31/237908.html
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