今天在做毕业实际的过程，报如下异常：
org.springframework.dao.InvalidDataAccessApiUsageException: The given object has a null identifier: com.paixie.domain.Users;
出现这个异常，一般来说主要修改时候主键没有传递或者name属性指定错误。<wbr></wbr>
解决方案：你要把你的更新的实例的主键传过去，可以以hidden的方式传。
<s:hidden name="action中实例对象名.id" id="id"></s:hidden>
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