有关hibernate的复合模式的帮助

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 Tree和TreeItems）结构来显示文件夹列表（类Folder）和文件（类FileLocation），文件夹和filelocation类将全部基于复合模式的类实现Hierarchy接口。 但我使用hibernate来存储我的数据，我正在使用注释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。

你有没有人使用复合模式，同时用hibernate持久化数据

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 children = new ArrayList() ; @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; 

Answer 1

看了一下hibernate文档和本书后我能够找到解决问题的方法。 我暂时不能使用JPA注释的界面。 所以我使用了一个带有支持inheritance的映射的抽象类。 在此示例中，我使用单个表来存储所有值。 但我会考虑分开它们。

 @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 children = new ArrayList() ; @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; 

Answer 2

Composite是非常基本的hibernate映射，应该不是问题。
但我不明白Mapping。 我假设FOLDER_FILELOCATION是Folder和FileInformation之间的LinkTable。 如果是这样，你实际上没有OneToMany而是ManyToMany Relation。 但是你可以将它映射为OneToMany。
你面临的问题是什么？ 要获得更精确的答案，请花更多时间来解释您的具体问题。 格式化给定的代码也有帮助，但是，我会尝试一下。

我不完全确定，但我认为基于模型，我认为你应该尝试这个：

 public interface Hierarchy(){ // a few abstract methods that will be implemented by the sub classes } @Entity @Table(name = "FOLDER_TABLE") public class Folder implements Hierarchy, Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "folder_id", updatable = false, nullable = false) private int id; @OneToMany @JoinTable( name="FOLDER_FILELOCATION", joinColumns = @JoinColumn( name="folder_id"), inverseJoinColumns = @JoinColumn( name="filelocation_id") ) private List children = new ArrayList() ; @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 Hierarchy, Serializable { @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; @ManyToOne( cascade = {CascadeType.PERSIST, CascadeType.MERGE} ) @JoinTable(name="FOLDER_FILELOCATION", joinColumns = @JoinColumn(name="filelocation_id"), inverseJoinColumns = @JoinColumn(name="folder_ID") ) private Hierarchy parent; } 

希望这会有所帮助。

Answer 3

我不是100％肯定你正在尝试做什么（你正在extending一个接口， parent缺少@ManyToOne注释）但据我所知，接口不受注释支持（它们不属于JPA规范）。 见HHH-4413以及此讨论 。 您可能需要使用XML映射来代替。