有关hibernate组合模式的帮助 [英] Help regarding composite pattern with hibernate

问题描述

所以我被卡住了，我正在创建一个gwt web应用程序，我将使用树（gwt树和TreeItems）结构来显示文件夹（类文件夹）和文件（类FileLocation）的列表，文件夹和文件位置类都将实现基于复合模式类的Hierarchy接口。但我使用Hibernate来存储我的数据，并且我使用注释来将数据映射到数据库。我的麻烦是我不知道如何注释我的界面。

有你们中的任何一个人在使用hibernate持久化数据时使用了复合模式

  public interface Hierarchy（）{
 //将由子类实现的几个抽象方法
} 
 
 
 @Entity 
 @Table（）
 public class Folder实现Serializable，Hierarchy {
 @Id 
 @GeneratedValue（strategy = GenerationType.AUTO）
 @Column（name =folder_id，可更新= false，nullable = false）
 private int id; 
 @OneToMany（cascade = CascadeType.ALL，fetch = FetchType.EAGER）
 @JoinTable（name =FOLDER_FILELOCATION，joinColumns = {
 @JoinColumn（name =folder_id）} inverseJoinColumns = {
 @JoinColumn（name =file_information_id）}）
 private List< Hierarchy> children = new ArrayList< Hierarchy>（）; 
 @Column（name =folder_name）
 private String folderName; 
 @Column（name =tree_item）
私人TreeItem项目; 
 @Column（name =parent）
私有层次结构parent; 
 
 
 
 
 $ b @Entity 
 @Table（name =FILE_INFORMATION_TABLE）
 public class FileInformation实现可序列化，层次结构{
 
 @Id 
 @GeneratedValue（strategy = GenerationType.AUTO）
 @Column（name =file_information_id，updatable = false，nullable = false）
 private int fiId; 
 @Column（name =location）
私人字符串位置; 
 @Column（name =tree_item）
私人TreeItem项目; 
 @Column（name =parent）
 @ManyToOne（cascade = {CascadeType.PERSIST，CascadeType.MERGE}）
 @JoinTable（name =FOLDER_FILELOCATION，
 joinColumns = @JoinColumn（name =filelocation_id），
 inverseJoinColumns = @JoinColumn（name =folder_ID））
 private parent Hierarchy parent; 
  

解决方案

在浏览hibernate文档和本书我能找到解决我的问题的方法。使用JPA批注时，我无法使用接口。所以我使用了支持继承的映射的抽象类。在这个例子中，我使用单个表来存储所有的值。但我会仔细分析它们。

  @Entity 
 @Table（name =HIERARCHY）
 @Inheritance（strategy = InheritanceType.SINGLE_TABLE）@DiscriminatorColumn（
 name =HIERARCHY_TYPE，discriminatorType = DiscriminatorType.STRING）
公共抽象类Hierarchy实现Serializable {
 
 @ Id 
 @GeneratedValue（strategy = GenerationType.AUTO）
 @Column（name =hierarchy_id，updatable = false，nullable = false）
 private int hId; 
 
 
 
 @实体
 @DiscriminatorValue（F）
公共类文件夹扩展层次结构{
 
 @OneToMany（ cascade = CascadeType.ALL，fetch = FetchType.EAGER）
 @JoinTable（name =FOLDER_JOIN_FILELOCATION，joinColumns = {
 @JoinColumn（name =folder_id）}，inverseJoinColumns = {
 @JoinColumn（name =file_information_id）}）
 private List< Hierarchy> children = new ArrayList< Hierarchy>（）; 
 @Column（name =folder_name）
 private String folderName; 
 // @ Column（name =tree_item）
 //私人TreeItem项目; 
 @ManyToOne（cascade = {CascadeType.PERSIST，CascadeType.MERGE}）
 @JoinTable（name =FOLDER_JOIN_FOLDER，
 joinColumns = @JoinColumn（name =parent_folder_id），
 inverseJoinColumns = @JoinColumn（name =folder_ID）
）
私有层次结构parent; 
 
 
 
 
 @实体
 @ DiscriminatorValue（FI）
公共类FileInformation扩展层次结构{
 
 
 @Column（name =location）
私人字符串位置; 
 // @ Column（name =tree_item）
 //私人TreeItem项目; 
 @ManyToOne（cascade = {CascadeType.PERSIST，CascadeType.MERGE}）
 @JoinTable（name =FILEINFORMATION_JOIN_FOLDER，
 joinColumns = @JoinColumn（name =filelocation_id），
 inverseJoinColumns = @JoinColumn（name =folder_ID）
）
私有层次结构parent; 
  

So i am stuck, i am creating a gwt web application, i will be using a tree(gwt Tree and TreeItems) structure to show a list of folders(class Folder) and files(class FileLocation), the folder and filelocation class will all implement a Hierarchy interface basing the classes on the composite pattern. but i am using hibernate to store my data , and i am using annotations for the mapping of the data to the database. my trouble is i do not know how to annotate my interface.

have any of you guys used the composite pattern while persisting the data with hibernate

public interface Hierarchy(){
// a few abstract methods that will be implemented by the sub classes
 }


@Entity
@Table()
public class Folder implements Serializable, Hierarchy {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "folder_id", updatable = false, nullable = false)
private int id;
@OneToMany(cascade = CascadeType.ALL,fetch = FetchType.EAGER)
@JoinTable(name = "FOLDER_FILELOCATION", joinColumns = { 
        @JoinColumn(name = "folder_id") }, inverseJoinColumns = { 
        @JoinColumn(name = "file_information_id") })
private List<Hierarchy> children = new ArrayList<Hierarchy>() ;
@Column(name = "folder_name")
private String folderName;
@Column(name = "tree_item")
private TreeItem item;
@Column (name = "parent")
private Hierarchy parent;



@Entity
@Table(name = "FILE_INFORMATION_TABLE")
public class FileInformation implements Serializable, Hierarchy {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "file_information_id", updatable = false, nullable = false)
private int fiId;
@Column (name = "location")
private String location;
@Column(name = "tree_item")
private TreeItem item;
@Column (name = "parent")
    @ManyToOne( cascade = {CascadeType.PERSIST, CascadeType.MERGE} )
    @JoinTable(name="FOLDER_FILELOCATION",
    joinColumns = @JoinColumn(name="filelocation_id"),
    inverseJoinColumns = @JoinColumn(name="folder_ID"))  
private Hierarchy parent;

解决方案

After a look through the hibernate documentation and This Book i was able to find a solution to my problem. i cannot use an interface for the moment with JPA annotations. so i used an abstract class with mappings that supported inheritance. in this example i use a single table to store all the values. but i wil look in to seperating them.

@Entity
@Table(name ="HIERARCHY")
@Inheritance(strategy = InheritanceType.SINGLE_TABLE) @DiscriminatorColumn(
    name = "HIERARCHY_TYPE", discriminatorType = DiscriminatorType.STRING)      
public abstract class  Hierarchy implements Serializable {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "hierarchy_id", updatable = false, nullable = false)
private int hId;



@Entity
@DiscriminatorValue("F")
public class Folder extends Hierarchy  {

@OneToMany(cascade = CascadeType.ALL,fetch = FetchType.EAGER)
@JoinTable(name = "FOLDER_JOIN_FILELOCATION", joinColumns = { 
        @JoinColumn(name = "folder_id") }, inverseJoinColumns = { 
        @JoinColumn(name = "file_information_id") })
private List<Hierarchy> children = new ArrayList<Hierarchy>() ;
@Column(name = "folder_name")
private String folderName;
//@Column(name = "tree_item")
//private TreeItem item;
@ManyToOne( cascade = {CascadeType.PERSIST, CascadeType.MERGE} )
   @JoinTable(name="FOLDER_JOIN_FOLDER",
        joinColumns = @JoinColumn(name="parent_folder_id"),
        inverseJoinColumns = @JoinColumn(name="folder_ID")
    ) 
private Hierarchy parent;




@Entity
@DiscriminatorValue("FI")
public class FileInformation extends Hierarchy  {


@Column (name = "location")
private String location;
//@Column(name = "tree_item")
//private TreeItem item;
@ManyToOne( cascade = {CascadeType.PERSIST, CascadeType.MERGE} )
   @JoinTable(name="FILEINFORMATION_JOIN_FOLDER",
        joinColumns = @JoinColumn(name="filelocation_id"),
        inverseJoinColumns = @JoinColumn(name="folder_ID")
    )  
private Hierarchy parent;

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