为什么我得到这个异常?
package com.domain.idea;
import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;
import javax.persistence.Table;
import org.hibernate.annotations.AccessType;
/**
* object model for the view [InvestmentReturn].[vMAE_MFE]
*/
@Entity
@Table(name="vMAE_MFE", schema="InvestmentReturn")
@AccessType("field")
public class MAE_MFEView
{
/**
* trade property is a SuggestdTradeRecommendation object
*/
@OneToOne(fetch = FetchType.LAZY , cascade = { CascadeType.PERSIST })
@JoinColumn(name = "suggestedTradeRecommendationID")
private SuggestedTradeRecommendation trade;
/**
* Most Adeverse Excursion value
*/
private int MAE;
public int getMAE()
{
return MAE;
}
/**
* Most Favorable Excursion value
*/
private int MFE;
public int getMFE()
{
return MFE;
}
/**
* @return trade property
* see #trade
*/
public SuggestedTradeRecommendation getTrade()
{
return trade;
}
}
更新:我已经改变了我的代码看起来像这样:
package com.domain.idea;
import javax.persistence.CascadeType;
import javax.persistence.FetchType;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;
import javax.persistence.Table;
import org.hibernate.annotations.AccessType;
/**
* object model for the view [InvestmentReturn].[vMAE_MFE]
*/
@Entity
@Table(name="vMAE_MFE", schema="InvestmentReturn")
@AccessType("field")
public class MAE_MFEView
{
/**
* trade property is a SuggestdTradeRecommendation object
*/
@Id
@OneToOne(fetch = FetchType.LAZY , cascade = { CascadeType.PERSIST })
@JoinColumn(name = "suggestedTradeRecommendationID")
private SuggestedTradeRecommendation trade;
/**
* Most Adeverse Excursion value
*/
private int MAE;
public int getMAE()
{
return MAE;
}
/**
* Most Favorable Excursion value
*/
private int MFE;
public int getMFE()
{
return MFE;
}
/**
* @return trade property
* see #trade
*/
public SuggestedTradeRecommendation getTrade()
{
return trade;
}
}
但现在我得到这个异常:
Caused by: org.hibernate.MappingException: Could not determine type for: com.domain.idea.SuggestedTradeRecommendation, at table: vMAE_MFE, for columns: [org.hibernate.mapping.Column(trade)]
at org.hibernate.mapping.SimpleValue.getType(SimpleValue.java:292)
at org.hibernate.mapping.SimpleValue.isValid(SimpleValue.java:276)
at org.hibernate.mapping.RootClass.validate(RootClass.java:216)
at org.hibernate.cfg.Configuration.validate(Configuration.java:1135)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1320)
at org.hibernate.cfg.AnnotationConfiguration.buildSessionFactory(AnnotationConfiguration.java:867)
at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:669)
... 145 more
您缺少一个用@Id
注释的字段。每个@Entity
都需要一个@Id
-这是数据库中的主键。
如果你不希望你的实体被保存在一个单独的表中,而是成为其他实体的一部分,你可以使用@Embeddable
而不是@Entity
。
如果您只希望一个数据传输对象来保存来自休眠实体的一些数据,则无论如何都不要在其上使用注释-将其保留为简单的 pojo。
更新:关于 SQL 视图,Hibernate 文档写:
Hibernate 映射的视图和基表之间没有区别。这在数据库级别是透明的

对我来说,应该使用javax.persistence.Id
而不是org.springframework.data.annotation.Id
。对于遇到此问题的任何人,您可以检查是否导入了正确的Id
类。
当您为 @ Id 导入与Javax.persistance.Id不同的库时,可能会引发此错误;您可能需要注意这种情况
在我的情况下,我有
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Table;
import org.springframework.data.annotation.Id;
@Entity
public class Status {
@Id
@GeneratedValue
private int id;
当我改变这样的代码,它得到了工作
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Table;
import javax.persistence.Id;
@Entity
public class Status {
@Id
@GeneratedValue
private int id;

下面的代码可以解决 NullPointerException。
@Id
@GeneratedValue
@Column(name = "STOCK_ID", unique = true, nullable = false)
public Integer getStockId() {
return this.stockId;
}
public void setStockId(Integer stockId) {
this.stockId = stockId;
}
如果你添加@Id
,那么你可以声明一些更像上面声明的方法。
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