我有两个表,VIDEO、VIDEOCATEGORY和连接表VIDEO2VIDEOOCATEGORY。我正在尝试进行多对多的注释。编译中没有错误或警告。
数据库一开始是空的。我尝试持久化视频实体(带有VideoCategory列表)。。此时一切都是正确的。新视频已添加到数据库中。还添加了一些新类别。然后我尝试添加具有新的独特类别的新视频。。。同样正确。问题是,当我尝试添加DB中已经存在类别的新视频时。在这次尝试之前,我在VIDEO2VIDEOCATEGORY("cat1",3)和("cat2",3。。。在尝试之后,应该有2个新记录-("cat1",4)和("cat2",4。他们被两个新记录改写了。
如何解决?我的代码:
import java.io.Serializable;
import java.util.List;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import org.hibernate.annotations.Cascade;
@Entity
public class VideoCategory implements Serializable{
private static final long serialVersionUID = -722840296120424003L;
@Id
@Column(name = "id", unique = true, nullable = false)
private String id;
@ManyToMany(fetch=FetchType.EAGER)
@Cascade(org.hibernate.annotations.CascadeType.SAVE_UPDATE)
@JoinTable(name = "video2videocategory",
joinColumns = {@JoinColumn(name = "cat_id")}, inverseJoinColumns = @JoinColumn(name = "vid_id"))
private List videos;
public VideoCategory(){
}
public VideoCategory(String id) {
super();
this.id = id;
}
public String getId() {
return id;
}
public void setId(String id){
this.id = id;
}
public List getVideos() {
return videos;
}
public void setVideos(List videos) {
this.videos = videos;
}
@Override
public String toString() {
return "VideoCategory [id=" + id + ", videos=" + videos + "]";
}
}
import java.io.Serializable;
import java.util.Date;
import java.util.List;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.EnumType;
import javax.persistence.Enumerated;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.SequenceGenerator;
import javax.persistence.JoinColumn;
import org.hibernate.annotations.Cascade;
@Entity
@SequenceGenerator(
name="VID_SEQ_GEN",
sequenceName="VIDSEQ",
allocationSize=1
)
public class Video implements Serializable {
private static final long serialVersionUID = 2284488937952510797L;
@Id @GeneratedValue(strategy = GenerationType.SEQUENCE, generator="VID_SEQ_GEN")
@Column(name = "id", unique = true, nullable = false)
private Long id;
@Column(name = "title", unique = false, nullable = false)
private String title;
@Column(name = "video_path", unique = false, nullable = false)
private String videoPath;
@Column(name = "video_type", unique = false, nullable = false)
@Enumerated(value=EnumType.STRING)
private VideoType videoType;
@Column(name = "creation_date", unique = false, nullable = false)
private Date creationDate;
@ManyToMany
@Cascade(org.hibernate.annotations.CascadeType.SAVE_UPDATE)
@JoinTable(name = "video2videocategory",
joinColumns = {@JoinColumn(name = "vid_id")}, inverseJoinColumns = @JoinColumn(name = "cat_id"))
private List categories;
public Video(){
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getVideoPath() {
return videoPath;
}
public void setVideoPath(String videoPath) {
this.videoPath = videoPath;
}
public VideoType getVideoType() {
return videoType;
}
public void setVideoType(VideoType videoType) {
this.videoType = videoType;
}
public Date getCreationDate() {
return creationDate;
}
public void setCreationDate(Date creationDate) {
this.creationDate = creationDate;
}
public List getCategories() {
return categories;
}
public void setCategories(List categories) {
this.categories = categories;
}
@Override
public String toString() {
return "Video [id=" + id + ", creationDate="
+ creationDate + ", title=" + title
+ ", videoPath=" + videoPath + ", videoType=" + videoType + "]";
}
}
我已经尝试过jpa和hibernate注释。
请帮忙。
错误可能是您将多对多关系定义为双方的父关系。一边应该是孩子,像这样:
@ManyToMany(mappedBy = "categories") // in the class VideoCategory