redhat-linux面试题
2010-08-10 19:11
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异常1:not-null property references a null or transient value
解决方法:将“一对多”关系中的“一”方,not-null设置为false
(参考资料:http://www.thearcmind.com/confluence/pages/viewpage.action?pageId=212)
异常2:org.hibernate.TransientObjectException: object references an unsaved transient instance
解决方法:cascade="save-update,persist"
(参考资料:http://www.laliluna.de/254.html)
异常3:org.hibernate.QueryException: could not resolve property
解决方法:"from Category category where category.userID = :userID"修改为"from Category category where userID = :userID"或者"from Category category where category.user.id = :userID"
(参考资料:http://www.laliluna.de/277.html)
异常4:could not initialize proxy - the owning Session was closed
解决方法:设置lazy为false
(参考资料:http://forum.springframework.org/showthread.php?t=27993)
异常2我在应用中碰到了这样的问题:
有三个表:userInfo deptmentInfo role
userInfo 与deptmentInfo为many to one
userInfo 与role为many to one
下面为保存UserInfo对象时的代码:
DeptmentInfo dept = new DeptmentInfo();
dept.setDeptName(deptName);
Role role = new Role();
role.setRoleName(roleName);
UserInfo user = new UserInfo();
user.setUserName(userName);
user.setUserSex(userSex);
user.setDuty(duty);
user.setPhone(phone);
user.setMobileNum(mobileNum);
user.setEmail(email);
user.setQq(qq);
user.setMsn(msn);
user.setAdress(adress);
user.setDeptmentInfo(dept);
user.setRole(role);
dao.save(user);
执行时有错:org.hibernate.TransientObjectException: object references an unsaved transient instance
于是改了UserInfo.hbm.xml的一些地方
如下:
<many-to-one name="role" class="com.oa.domain.Role"
cascade="save-update,persist" fetch="select">
<column name="ROLE_ID" precision="22" scale="0" />
</many-to-one>
<many-to-one name="deptmentInfo"
class="com.oa.domain.DeptmentInfo" cascade="save-update,persist"
fetch="select">
<column name="DEPT_ID" precision="22" scale="0" />
</many-to-one>
加了上面红色部分的,就OK了,能保存了。
解决方法:将“一对多”关系中的“一”方,not-null设置为false
(参考资料:http://www.thearcmind.com/confluence/pages/viewpage.action?pageId=212)
异常2:org.hibernate.TransientObjectException: object references an unsaved transient instance
解决方法:cascade="save-update,persist"
(参考资料:http://www.laliluna.de/254.html)
异常3:org.hibernate.QueryException: could not resolve property
解决方法:"from Category category where category.userID = :userID"修改为"from Category category where userID = :userID"或者"from Category category where category.user.id = :userID"
(参考资料:http://www.laliluna.de/277.html)
异常4:could not initialize proxy - the owning Session was closed
解决方法:设置lazy为false
(参考资料:http://forum.springframework.org/showthread.php?t=27993)
异常2我在应用中碰到了这样的问题:
有三个表:userInfo deptmentInfo role
userInfo 与deptmentInfo为many to one
userInfo 与role为many to one
下面为保存UserInfo对象时的代码:
DeptmentInfo dept = new DeptmentInfo();
dept.setDeptName(deptName);
Role role = new Role();
role.setRoleName(roleName);
UserInfo user = new UserInfo();
user.setUserName(userName);
user.setUserSex(userSex);
user.setDuty(duty);
user.setPhone(phone);
user.setMobileNum(mobileNum);
user.setEmail(email);
user.setQq(qq);
user.setMsn(msn);
user.setAdress(adress);
user.setDeptmentInfo(dept);
user.setRole(role);
dao.save(user);
执行时有错:org.hibernate.TransientObjectException: object references an unsaved transient instance
于是改了UserInfo.hbm.xml的一些地方
如下:
<many-to-one name="role" class="com.oa.domain.Role"
cascade="save-update,persist" fetch="select">
<column name="ROLE_ID" precision="22" scale="0" />
</many-to-one>
<many-to-one name="deptmentInfo"
class="com.oa.domain.DeptmentInfo" cascade="save-update,persist"
fetch="select">
<column name="DEPT_ID" precision="22" scale="0" />
</many-to-one>
加了上面红色部分的,就OK了,能保存了。
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