hibernate 懒加载问题

[king3320x]

<one-to-one name="per" constrained="true" lazy="proxy"/>

在这句中 为什么我加了constrained="true"这句就出现错误，去掉可以正常的运行，
错误信息：
Exception in thread "main" org.hibernate.exception.GenericJDBCException: could not load an entity: [com.user.IdCard#1]
at org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:103)
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:91)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
at org.hibernate.loader.Loader.loadEntity(Loader.java:1874)
at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:48)
at org.hibernate.loader.entity.EntityLoader.loadByUniqueKey(EntityLoader.java:85)
at org.hibernate.persister.entity.AbstractEntityPersister.loadByUniqueKey(AbstractEntityPersister.java:1649)
at org.hibernate.type.EntityType.loadByUniqueKey(EntityType.java:608)
at org.hibernate.type.EntityType.resolve(EntityType.java:382)
at org.hibernate.engine.TwoPhaseLoad.initializeEntity(TwoPhaseLoad.java:120)
at org.hibernate.loader.Loader.initializeEntitiesAndCollections(Loader.java:854)
at org.hibernate.loader.Loader.doQuery(Loader.java:729)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:236)
at org.hibernate.loader.Loader.loadEntity(Loader.java:1860)
at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:48)
at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:42)
at org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:3049)
at org.hibernate.event.def.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:399)
at org.hibernate.event.def.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:375)
at org.hibernate.event.def.DefaultLoadEventListener.load(DefaultLoadEventListener.java:139)
at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:98)
at org.hibernate.impl.SessionImpl.fireLoad(SessionImpl.java:878)
at org.hibernate.impl.SessionImpl.immediateLoad(SessionImpl.java:836)
at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:66)
at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:111)
at org.hibernate.proxy.pojo.cglib.CGLIBLazyInitializer.invoke(CGLIBLazyInitializer.java:150)
at com.user.Person$$EnhancerByCGLIB$$593dcbd9.toString(<generated>)
at java.lang.String.valueOf(Unknown Source)
at java.io.PrintStream.println(Unknown Source)
at com.test.One2one.query(One2one.java:35)
at com.test.One2one.main(One2one.java:19)
Caused by: java.sql.SQLException: Parameter index out of range (1 > 0).
at com.mysql.jdbc.PreparedStatement.setInternal(PreparedStatement.java:1940)
at com.mysql.jdbc.PreparedStatement.setInternal(PreparedStatement.java:1967)
at com.mysql.jdbc.PreparedStatement.setInt(PreparedStatement.java:509)
at org.hibernate.type.IntegerType.set(IntegerType.java:41)
at org.hibernate.type.NullableType.nullSafeSet(NullableType.java:136)
at org.hibernate.type.NullableType.nullSafeSet(NullableType.java:116)
at org.hibernate.loader.Loader.bindPositionalParameters(Loader.java:1707)
at org.hibernate.loader.Loader.bindParameterValues(Loader.java:1678)
at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1563)
at org.hibernate.loader.Loader.doQuery(Loader.java:673)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:236)
at org.hibernate.loader.Loader.loadEntity(Loader.java:1860)
... 27 more

[king3320x]

IdCard idcard=(IdCard)s.get(IdCard.class,id);
System.out.println("h");

以上正确，
System.out.println(idcard.getPer().getName());加了这句
加载数据库时候出现了以上错误

[fdgaq]

constrained="true" 这个设置说明在idcard这个类中，有一个per_id的外键与person类中的id主键是互相约束的，你在idcard.cfg.xml看看有没有per_id这个外键约束设置。

[loveunittesting]

外键不匹配造成的，应该是你的数据库实际不包含外键，更新一下数据就ok了