Hibernate JPA使用相同的名称连接外键

让我们假设我有：

表编辑器（id、企业名称、增值税）

表作者（id、姓名、电子邮件）

表书籍（id、标题、描述、fk_作者、fk_编辑）

假设fk_editor是表编辑器id字段的外键，fk_author是表作者id字段的外键

让我们假设图书：作者是n:1和图书：编辑是n:1

问题是：如何通过books表连接这三个表？ 这意味着，我必须在Book类中添加什么代码才能让Hibernate理解如何创建与作者和编辑的关系？请考虑在作者和编辑器中有相同的ID字段名。 下面是我需要更正的示例代码：

表作者：

package com.bytecode.jpaexample.SpringBootMySqlJpaRestExample;

import javax.persistence.*;
import java.io.Serializable;

@Entity
@Table(name = "authors")
public class Author implements Serializable{

   @Id
   @GeneratedValue(strategy = GenerationType.AUTO)
   @Column(name = "id")
   @OneToMany(fetch = FetchType.LAZY)
   private int id;

   @Column(name = "name")
   private String name;

   @Column(name = "surname")
   private String surname;

   @Column(name = "email")
   private String email;

   /* constructors and getters and setters omitted intentionally */

}

package com.bytecode.jpaexample.SpringBootMySqlJpaRestExample;

import javax.persistence.*;
import java.io.Serializable;

@Entity
@Table(name = "editors")
public class Editor implements Serializable{

   @Id
   @GeneratedValue(strategy = GenerationType.AUTO)
   @Column(name = "id")
   @OneToMany(fetch = FetchType.LAZY)
   private int id;

   @Column(name = "business_name")
   private String businessName;

   @Column(name = "vat")
   private String vat;

   /* constructors and getters and setters omitted intentionally */

}

package com.bytecode.jpaexample.SpringBootMySqlJpaRestExample;

import javax.persistence.*;
import java.io.Serializable;

@Entity
@Table(name="books")
public class Book implements Serializable{

   @Id
   @GeneratedValue(strategy = GenerationType.AUTO)
   @Column(name = "id")
   private int id;

   @Column(name = "title")
   private String title;

   @Column(name = "description")
   private String description;

   @ManyToOne(fetch = FetchType.LAZY)      
   @JoinColumn(name = "id") //authors.id                
   @Column(name = "fk_author")
   private int fk_editor;

   @ManyToOne(fetch = FetchType.LAZY)      
   @JoinColumn(name = "id") //editors.id                
   @Column(name = "fk_editor")
   private int fk_editor;

   /* constructors and getters and setters omitted intentionally */
}

表编辑器：

package com.bytecode.jpaexample.SpringBootMySqlJpaRestExample;

import javax.persistence.*;
import java.io.Serializable;

@Entity
@Table(name = "authors")
public class Author implements Serializable{

   @Id
   @GeneratedValue(strategy = GenerationType.AUTO)
   @Column(name = "id")
   @OneToMany(fetch = FetchType.LAZY)
   private int id;

   @Column(name = "name")
   private String name;

   @Column(name = "surname")
   private String surname;

   @Column(name = "email")
   private String email;

   /* constructors and getters and setters omitted intentionally */

}

package com.bytecode.jpaexample.SpringBootMySqlJpaRestExample;

import javax.persistence.*;
import java.io.Serializable;

@Entity
@Table(name = "editors")
public class Editor implements Serializable{

   @Id
   @GeneratedValue(strategy = GenerationType.AUTO)
   @Column(name = "id")
   @OneToMany(fetch = FetchType.LAZY)
   private int id;

   @Column(name = "business_name")
   private String businessName;

   @Column(name = "vat")
   private String vat;

   /* constructors and getters and setters omitted intentionally */

}

package com.bytecode.jpaexample.SpringBootMySqlJpaRestExample;

import javax.persistence.*;
import java.io.Serializable;

@Entity
@Table(name="books")
public class Book implements Serializable{

   @Id
   @GeneratedValue(strategy = GenerationType.AUTO)
   @Column(name = "id")
   private int id;

   @Column(name = "title")
   private String title;

   @Column(name = "description")
   private String description;

   @ManyToOne(fetch = FetchType.LAZY)      
   @JoinColumn(name = "id") //authors.id                
   @Column(name = "fk_author")
   private int fk_editor;

   @ManyToOne(fetch = FetchType.LAZY)      
   @JoinColumn(name = "id") //editors.id                
   @Column(name = "fk_editor")
   private int fk_editor;

   /* constructors and getters and setters omitted intentionally */
}

表书籍：

package com.bytecode.jpaexample.SpringBootMySqlJpaRestExample;

import javax.persistence.*;
import java.io.Serializable;

@Entity
@Table(name = "authors")
public class Author implements Serializable{

   @Id
   @GeneratedValue(strategy = GenerationType.AUTO)
   @Column(name = "id")
   @OneToMany(fetch = FetchType.LAZY)
   private int id;

   @Column(name = "name")
   private String name;

   @Column(name = "surname")
   private String surname;

   @Column(name = "email")
   private String email;

   /* constructors and getters and setters omitted intentionally */

}

package com.bytecode.jpaexample.SpringBootMySqlJpaRestExample;

import javax.persistence.*;
import java.io.Serializable;

@Entity
@Table(name = "editors")
public class Editor implements Serializable{

   @Id
   @GeneratedValue(strategy = GenerationType.AUTO)
   @Column(name = "id")
   @OneToMany(fetch = FetchType.LAZY)
   private int id;

   @Column(name = "business_name")
   private String businessName;

   @Column(name = "vat")
   private String vat;

   /* constructors and getters and setters omitted intentionally */

}

package com.bytecode.jpaexample.SpringBootMySqlJpaRestExample;

import javax.persistence.*;
import java.io.Serializable;

@Entity
@Table(name="books")
public class Book implements Serializable{

   @Id
   @GeneratedValue(strategy = GenerationType.AUTO)
   @Column(name = "id")
   private int id;

   @Column(name = "title")
   private String title;

   @Column(name = "description")
   private String description;

   @ManyToOne(fetch = FetchType.LAZY)      
   @JoinColumn(name = "id") //authors.id                
   @Column(name = "fk_author")
   private int fk_editor;

   @ManyToOne(fetch = FetchType.LAZY)      
   @JoinColumn(name = "id") //editors.id                
   @Column(name = "fk_editor")
   private int fk_editor;

   /* constructors and getters and setters omitted intentionally */
}

有几件事：

Author

和

Editor

类的

id

字段不应使用

@OneToMany

注释：

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id")
    private int id;

相反，我猜每个类中都需要另一个字段：

@Entity
@Table(name = "authors")
public class Author implements Serializable {
    ...
    @OneToMany(mappedBy = "author", fetch = FetchType.LAZY)
    private List<Book> books;
    ...
}

@Entity
@Table(name = "editors")
public class Editor implements Serializable {
    ...
    @OneToMany(mappedBy = "editor", fetch = FetchType.LAZY)
    private List <Book> books;
    ...
}