java - 如何使用 Hibernate 设置 getter、setter 和数据库字段的不同类型？

Question

我在 H2 数据库中有一个时间戳字段，但我需要使用 Hibernate 4.3 从我的 bean 中获取字符串而不是日期，所以我尝试在我的 bean 中这样做:

import java.util.Date;

...

private Date msgDate;
@Column(name = "msgDate", columnDefinition="timestamp")
public String getMsgDate() {
    SimpleDateFormat df = new SimpleDateFormat("yyyy MM dd HH mm ss");
    return df.format(msgDate);
}

public void setMsgDate(Date msgDate) {
    this.msgDate = msgDate;
}

但我有下一个错误:

    ERROR: HHH000123: IllegalArgumentException in class: Messages, setter method of property: msgDate
июл 03, 2013 11:39:56 AM org.hibernate.property.BasicPropertyAccessor$BasicSetter set
ERROR: HHH000091: Expected type: java.util.Date, actual value: java.lang.String
июл 03, 2013 11:39:56 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [MessageList] in context with path [/messenger] threw exception
org.hibernate.PropertyAccessException: IllegalArgumentException occurred while calling setter of com.epam.epamlab.messenger.beans.Messages.msgDate
    at org.hibernate.property.BasicPropertyAccessor$BasicSetter.set(BasicPropertyAccessor.java:119)
    at org.hibernate.tuple.entity.AbstractEntityTuplizer.setPropertyValues(AbstractEntityTuplizer.java:711)
    at org.hibernate.tuple.entity.PojoEntityTuplizer.setPropertyValues(PojoEntityTuplizer.java:371)
    at org.hibernate.persister.entity.AbstractEntityPersister.setPropertyValues(AbstractEntityPersister.java:4519)
    at org.hibernate.engine.internal.TwoPhaseLoad.doInitializeEntity(TwoPhaseLoad.java:188)
    at org.hibernate.engine.internal.TwoPhaseLoad.initializeEntity(TwoPhaseLoad.java:144)
    at org.hibernate.loader.Loader.initializeEntitiesAndCollections(Loader.java:1102)
    at org.hibernate.loader.Loader.processResultSet(Loader.java:959)
    at org.hibernate.loader.Loader.doQuery(Loader.java:906)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:340)
    at org.hibernate.loader.Loader.doList(Loader.java:2523)
    at org.hibernate.loader.Loader.doList(Loader.java:2509)
    at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2339)
    at org.hibernate.loader.Loader.list(Loader.java:2334)
    at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:491)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:369)
    at org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:222)
    at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1270)
    at org.hibernate.internal.QueryImpl.list(QueryImpl.java:101)
    ...
Caused by: java.lang.IllegalArgumentException: argument type mismatch
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at org.hibernate.property.BasicPropertyAccessor$BasicSetter.set(BasicPropertyAccessor.java:65)
    ... 40 more

如果我从 getter 返回 Date，一切都会很好。为什么 Hibernate 等待返回 Date 类型，即使在注释中使用了 columnDefinition 之后也是如此？我应该如何正确地做到这一点？

Answer 1

保持 getter/setter 不变。 Hibernate需要这些方法与字段的类型一致才能执行操作。没有什么可以阻止您在类中定义自己的特殊 get 方法。

private Date msgDate;
@Column(name = "msgDate", columnDefinition="timestamp")
public Date getMsgDate() {
   return this.msgDate;
}

public void setMsgDate(Date msgDate) {
    this.msgDate = msgDate;
}

public Date getMsgDateFormatted() {
    SimpleDateFormat df = new SimpleDateFormat("yyyy MM dd HH mm ss");
    return df.format(msgDate);
}