我有一个实体,有一些懒加载的属性,我试图初始化一个特定的方法(大部分时间它太昂贵,这些被加载,所以他们不能被设置为EAGER)。Hibernate.initialize()被完全忽略
其中一个属性是一个集合,它在调用Hibernate.initialize()时加载得很漂亮。另一个是单个对象,不管我尝试什么都不会加载。我甚至不能查询它,因为对象的ID本身不可用,即使在同一个会话中也是如此。
我在调用initialize()时没有收到任何异常,它只是简单地被忽略。该日志在集合上调用此查询时会显示相应的查询,但不会显示在单个对象上。加载此属性(设备)的任何帮助,非常感谢。这是代码:
编辑 事实证明,我在数据库中缺少一个外键。一旦我纠正了这个问题,控制台上就会出现提取查询,但是在initialize()完成后Device对象仍然是一个代理。我想出了一个解决方法做这个:
Device device = new Device();
device.setIdDevice(surveyLog.getDevice().getIdDevice());
device.setName(surveyLog.getDevice().getName());
surveyLog.setDevice(device);
如果我的属性复制到另一个对象,它们可以在方法外部访问,否则对象仍然是一个代理。任何想法可能会造成这种情况?由于
@Transactional
public SurveyLog getById(Long id)
{
SurveyLog surveyLog = this.surveyLogDAO.findById(id);
Hibernate.initialize(surveyLog.getDevice()); //doesn't work
Hibernate.initialize(surveyLog.getSurveyAnswers()); //works like a charm
return surveyLog;
}
而这些是我的映射:
import static javax.persistence.GenerationType.IDENTITY;
import java.math.BigDecimal;
import java.sql.Timestamp;
import java.util.ArrayList;
import java.util.List;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import org.hibernate.annotations.Cascade;
import org.hibernate.annotations.CascadeType;
import org.hibernate.annotations.Fetch;
import org.hibernate.annotations.FetchMode;
import com.google.gson.annotations.Expose;
@Entity
@Table(name="SurveyLog")
public class SurveyLog
{
// Fields
@Expose private Long idSurveyLog;
@Expose private Survey survey;
@Expose private Device device;
@Expose private BigDecimal latitude;
@Expose private BigDecimal longitude;
@Expose private Timestamp timestamp;
@Expose private List<SurveyAnswerLog> surveyAnswers = new ArrayList<SurveyAnswerLog>();
/**
* Constructor.
*
*/
public SurveyLog() {}
// Property accessors
@Id
@GeneratedValue(strategy=IDENTITY)
@Column(name="idSurveyLog", unique=true, nullable=false)
public Long getIdSurveyLog()
{
return idSurveyLog;
}
public void setIdSurveyLog(Long idSurveyLog)
{
this.idSurveyLog = idSurveyLog;
}
@ManyToOne(fetch=FetchType.LAZY)
@JoinColumn(name="idSurvey", nullable=false)
public Survey getSurvey()
{
return survey;
}
public void setSurvey(Survey survey)
{
this.survey = survey;
}
@ManyToOne(fetch=FetchType.LAZY)
@Fetch(value = FetchMode.SELECT)
@JoinColumn(name="idDevice", nullable=false)
public Device getDevice()
{
return device;
}
public void setDevice(Device device)
{
this.device = device;
}
@Column(name="latitude", precision=8, scale=6)
public BigDecimal getLatitude()
{
return latitude;
}
public void setLatitude(BigDecimal latitude)
{
this.latitude = latitude;
}
@Column(name="longitude", precision=9, scale=6)
public BigDecimal getLongitude()
{
return longitude;
}
public void setLongitude(BigDecimal longitude)
{
this.longitude = longitude;
}
@Column(name="timestamp", length=19)
public Timestamp getTimestamp()
{
return timestamp;
}
public void setTimestamp(Timestamp timestamp)
{
this.timestamp = timestamp;
}
@OneToMany(fetch=FetchType.LAZY, mappedBy="surveyLog")
@Cascade({CascadeType.ALL, CascadeType.DELETE_ORPHAN})
public List<SurveyAnswerLog> getSurveyAnswers()
{
return surveyAnswers;
}
public void setSurveyAnswers(List<SurveyAnswerLog> surveyAnswers)
{
this.surveyAnswers = surveyAnswers;
}
}
import static javax.persistence.GenerationType.IDENTITY;
import java.util.EnumSet;
import java.util.HashMap;
import java.util.Map;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
import javax.persistence.UniqueConstraint;
import javax.persistence.Version;
import com.google.gson.annotations.Expose;
import com.sitei.base.model.City;
import com.sitei.base.model.Company;
@Entity
@Table(name="Device", uniqueConstraints = @UniqueConstraint(columnNames = "macAddress"))
public class Device
{
// Fields
@Expose private Integer idDevice;
@Expose private String macAddress;
@Expose private String name;
@Expose private String description;
@Expose private Short type;
@Expose private City city;
@Expose private Company company;
@Expose private Survey survey;
@Expose private Integer surveyPoints;
@Expose private boolean active;
@Expose private Long version;
/**
* Constructor.
*
*/
public Device() {}
// Property accessors
@Id
@GeneratedValue(strategy=IDENTITY)
@Column(name="idDevice", unique=true, nullable=false)
public Integer getIdDevice()
{
return idDevice;
}
public void setIdDevice(Integer idDevice)
{
this.idDevice = idDevice;
}
@Column(name="macAddress", nullable=false, length=17)
public String getMacAddress()
{
return macAddress;
}
public void setMacAddress(String macAddress)
{
this.macAddress = macAddress;
}
@Column(name="name", nullable=false, length=64)
public String getName()
{
return name;
}
public void setName(String name)
{
this.name = name;
}
@Column(name="description", length=256)
public String getDescription()
{
return description;
}
public void setDescription(String description)
{
this.description = description;
}
@Column(name="type", nullable=false)
public Short getType()
{
return type;
}
public void setType(Short type)
{
this.type = type;
}
@ManyToOne(fetch=FetchType.EAGER)
@JoinColumn(name="idCity", nullable=false)
public City getCity()
{
return city;
}
public void setCity(City city)
{
this.city = city;
}
@ManyToOne(fetch=FetchType.EAGER)
@JoinColumn(name="idCompany")
public Company getCompany()
{
return company;
}
public void setCompany(Company company)
{
this.company = company;
}
@ManyToOne(fetch=FetchType.EAGER)
@JoinColumn(name="idSurvey")
public Survey getSurvey()
{
return survey;
}
public void setSurvey(Survey survey)
{
this.survey = survey;
}
@Column(name="surveyPoints", nullable=false)
public Integer getSurveyPoints()
{
return surveyPoints;
}
public void setSurveyPoints(Integer surveyPoints)
{
this.surveyPoints = surveyPoints;
}
@Column(name="active", nullable=false)
public boolean isActive()
{
return active;
}
public void setActive(boolean active)
{
this.active = active;
}
@Version
public Long getVersion()
{
return version;
}
public void setVersion(Long version)
{
this.version = version;
}
}
因为我返回的对象将被序列化为JSON,并且为了能够访问这些属性的数据,我需要手动将它复制到另一个对象。出于某种原因,这在集合上的作用是不同的。在这种情况下,初始化会自动加载对象的属性,从而消除克隆对象的繁琐。 – JayPea
使用反射完成了JSON转换吗?尝试一种接口实现方法。 Hibernate总是使用代理来实现懒惰的一对一关系。对于一对多,它可以使用自定义集合类。 – sorencito
https://forum.hibernate.org/viewtopic.php?t=947035 – sorencito