如何在查詢視圖時返回實體列表

Question

我有兩個與一對多連接相關的實體。一個是Path另一個是Point，一個路徑可以有幾個點。我對使用連接表加入這些表的MySQL端有了一些看法。我需要獲得查詢結果到該視圖。這是第一

@Entity 
@Table(name = "paths") 
public class Path { 

    @JsonIgnore 
    @Id 
    @Column(name="id") 
    @GeneratedValue(strategy=GenerationType.AUTO) 
    private Long pathID; 
    @Column(name="path_name") 
    private String pathName; 
    @Column(name="path_type") 
    private Long pathType; 
    @OneToOne(fetch = FetchType.EAGER) 
    @JoinColumn(name="uid") 
    @JsonIgnore 
    private User owner; 
    @Column(name="path_status") 
    private Long pathStatus; 
    @Column(name="description") 
    private String pathDescription; 
    @Column(name="created") 
    private Long created; 
    @OneToMany(mappedBy = "primaryKey.point", cascade = CascadeType.ALL) 
    private Set<PathPoints> pathPoints = new HashSet<PathPoints>(); 

    public Long getPathID(){ 
     return this.pathID; 
    } 
    public void setPathID(Long pathID){ 
     this.pathID = pathID; 
    } 

    public String getPathName(){ 
     return this.pathName; 
    } 
    public void setPathName(String pathName){ 
     this.pathName = pathName; 
    } 

    public Long getPathType(){ 
     return this.pathType; 
    } 
    public void setPathType(Long pathType){ 
     this.pathType = pathType; 
    } 

    public Long getPathStatus(){ 
     return this.pathStatus; 
    } 
    public void setPathStatus(Long pathStatus){ 
     this.pathStatus = pathStatus; 
    } 

    public String getPathDescription(){ 
     return this.pathDescription; 
    } 
    public void setPathDescription(String pathDescription){ 
     this.pathDescription = pathDescription; 
    } 

    public Long getCreated(){ 
     return this.created; 
    } 
    public void setCreated(Long created){ 
     this.created = created; 
    } 
    public Set<PathPoints> getPathPoints() { 
     return pathPoints; 
    } 
    public void setPathPoints(Set<PathPoints> pathPoints) { 
     this.pathPoints = pathPoints; 
    } 
    public User getOwner() { 
     return owner; 
    } 
    public void setOwner(User owner) { 
     this.owner = owner; 
    } 

} 

這裏是第二

@Entity 
    @Table(name = "path_points") 
    @AssociationOverrides({ 
    @AssociationOverride(name = "primaryKey.point", joinColumns = @JoinColumn(name = "point_id")), 
    @AssociationOverride(name = "primaryKey.path", joinColumns = @JoinColumn(name = "path_id")) 
    }) 
public class PathPoints{ 

    private PathPointID primaryKey = new PathPointID(); 

    private Long endTime; 
    private Long startTime; 

    @Column(name="end_time") 
    public Long getEndTime() { 
     return endTime; 
    } 
    public void setEndTime(Long endTime) { 
     this.endTime = endTime; 
    } 
    @Column(name="start_time") 
    public Long getStartTime() { 
     return startTime; 
    } 
    public void setStartTime(Long startTime) { 
     this.startTime = startTime; 
    } 
    @JsonIgnore 
    @EmbeddedId 
    public PathPointID getPrimaryKey() { 
     return primaryKey; 
    } 
    public void setPrimaryKey(PathPointID primaryKey) { 
     this.primaryKey = primaryKey; 
    } 
    @Transient 
    public Point getPoint() { 
     return primaryKey.getPoint(); 
    } 
    public void setPoint(Point point) { 
     this.primaryKey.setPoint(point);; 
    } 
    @JsonIgnore 
    @Transient 
    public Path getPath() { 
     return primaryKey.getPath(); 
    } 
    public void setPath(Path path) { 
     this.primaryKey.setPath(path);; 
    } 

} 

這就是ID級別

@Embeddable 
public class PathPointID implements Serializable { 

/** 
* 
*/ 
private static final long serialVersionUID = 1L; 
private Point point; 
private Path path; 

@ManyToOne(cascade = CascadeType.ALL) 
public Point getPoint() { 
    return point; 
} 
public void setPoint(Point point) { 
    this.point = point; 
} 
@ManyToOne(cascade = CascadeType.ALL) 
public Path getPath() { 
    return path; 
} 
public void setPath(Path path) { 
    this.path = path; 
} 
} 

Answer 1

您需要創建第三實體類和JPA做/它休眠操作。

然後執行

YourView視圖= ... //由一些參數獲取該視圖的數據 view.setPoints（yourDaoMethodToGetPoints（視圖））;

你可以看到this的例子。我在這裏使用了PostgreSQL和JPA 2.1。我在數據庫中編寫了一個視圖，並將它映射到JPA實體。有一件事需要記住 - 您不能對此視圖執行寫操作。