a different object with the same identifier value was already associated withthe session异常解决方案

异常信息:

org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated withthe session

发生原因:

在对一个实体查询操作后,进行了set,然后又要对这个实体进行save/update,

报错的例子

//Service层
public void modifyPersonalizedSettings(PersonalizedSettings ps,Integer userId)throws Exception {
		
		User user = personalizedSettingsDAO.selectUserById(userId);
		ps.setUser(user);
		personalizedSettingsDAO.updatePersonalizedSettings(ps);
	}
//DAO层
public void updatePersonalizedSettings(PersonalizedSettings ps) throws Exception {
System.out.println(ps+"DAO");
template.merge(ps);
}

解决方案:

最简单的就是不用save()方法,改用merge()方法。

例子:

//Service层
public void modifyPersonalizedSettings(PersonalizedSettings ps,Integer userId)throws Exception {
		
		User user = personalizedSettingsDAO.selectUserById(userId);
		ps.setUser(user);
		personalizedSettingsDAO.updatePersonalizedSettings(ps);
	}
//DAO层
public void updatePersonalizedSettings(PersonalizedSettings ps) throws Exception {
System.out.println(ps+"DAO");
//template.update(ps)不再使用update()方法,改用merge()方法即可
template.merge(ps);
}

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原文地址:https://www.cnblogs.com/yunns/p/4867903.html