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51.4. 外键
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51.4. 外键

51.4.1. @JoinColumn

@JoinColumn与@Column注释类似，它的定义如下代码所示。 

			
@Target({METHOD, FIELD}) @Retention(RUNTIME) 

public @interface JoinColumn { 

String name() default ""; 

String referencedColumnName() default ""; 

boolean unique() default false; 

boolean nullable() default true; 

boolean insertable() default true; 

boolean updatable() default true; 

String columnDefinition() default ""; 

String table() default ""; 

}

定义外键名称 @ForeignKey(name = "picture_id")

				
    @Id
    @OneToOne(cascade = CascadeType.ALL, orphanRemoval = true)
    @JoinColumn(name = "id", foreignKey = @ForeignKey(name = "picture_id"))
    private Picture picture;				
				
			
				
CREATE TABLE `picture_psychoanalysis` (
  `analysis` text COMMENT '心里分析',
  `ctime` timestamp NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
  `emotion` varchar(255) DEFAULT NULL COMMENT '感谢|愉快|抱怨|愤怒|喜爱|厌恶|恐惧|悲伤',
  `mtime` timestamp NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP COMMENT '修改时间',
  `replies` text COMMENT '建议回复话术',
  `sentiment` varchar(255) DEFAULT NULL COMMENT '负向情绪|中性情绪|正向情绪',
  `id` bigint unsigned NOT NULL,
  PRIMARY KEY (`id`),
  CONSTRAINT `picture_id` FOREIGN KEY (`id`) REFERENCES `picture` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci COMMENT='文生图心里分析'

51.4.2. @OneToOne

一对一表结构，如下面ER图所示，users表是用户表里面有登陆信息，profile 保存的时死人信息，这样的目的是我们尽量减少users表的字段，在频繁操作该表的时候性能比较好，另外一个目的是为了横向水平扩展。 

			
    +----------+             +------------+
    | users    |             | profile    |
    +----------+             +------------+
    | id       | <---1:1---o | id         |
    | name     |             | sex        |    
    | password |             | email      |    
    +----------+             +------------+ 
			
			
			
package cn.netkiller.api.domain.test;

import java.io.Serializable;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "users")
public class Users implements Serializable {
	@Id
	@GeneratedValue(strategy = GenerationType.AUTO)
	private int id;
	private String name;
	private String password;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

	@Override
	public String toString() {
		return "Users [id=" + id + ", name=" + name + ", password=" + password + "]";
	}
}

			
			
			
package cn.netkiller.api.domain.test;

import java.io.Serializable;

import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;
import javax.persistence.Table;

@Entity
@Table(name = "profile")
public class Profile implements Serializable {
	/**
	 * 
	 */
	private static final long serialVersionUID = -2500499458196257167L;
	@Id
	@OneToOne
	@JoinColumn(name = "id")
	private Users users;

	private int age;
	private String sex;
	private String email;

	public Users getUsers() {
		return users;
	}

	public void setUsers(Users users) {
		this.users = users;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	public String getSex() {
		return sex;
	}

	public void setSex(String sex) {
		this.sex = sex;
	}

	public String getEmail() {
		return email;
	}

	public void setEmail(String email) {
		this.email = email;
	}

	@Override
	public String toString() {
		return "Profile [users=" + users + ", age=" + age + ", sex=" + sex + ", email=" + email + "]";
	}

}

			
			
			
CREATE TABLE `users` (
	`id` INT(11) NOT NULL AUTO_INCREMENT,
	`name` VARCHAR(255) NULL DEFAULT NULL,
	`password` VARCHAR(255) NULL DEFAULT NULL,
	PRIMARY KEY (`id`)
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB;
			
CREATE TABLE `profile` (
	`age` INT(11) NOT NULL,
	`email` VARCHAR(255) NULL DEFAULT NULL,
	`sex` VARCHAR(255) NULL DEFAULT NULL,
	`id` INT(11) NOT NULL,
	PRIMARY KEY (`id`),
	CONSTRAINT `FK6x079ilawxjrfsljwyyi5ujjq` FOREIGN KEY (`id`) REFERENCES `users` (`id`)
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB;

如果第二张表关联的并非主表的PK（主键）需要使用 referencedColumnName 指定。

			
@JoinColumn(name = "member_id",referencedColumnName="member_id")

51.4.2.1. 案例一

					
package cn.netkiller.domain.demo;

import jakarta.persistence.Entity;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.GenerationType;
import jakarta.persistence.Id;

@Entity
public class Book {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    private String name;

}
					
					
				
					
package cn.netkiller.domain.demo;

import jakarta.persistence.*;

@Entity
public class BookDetail {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;

    private long numberOfPages;

    @OneToOne
    private Book book;
}
					
					
				
					
CREATE TABLE `book` (
  `id` bigint NOT NULL AUTO_INCREMENT,
  `name` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci

CREATE TABLE `book_detail` (
  `id` bigint NOT NULL AUTO_INCREMENT,
  `number_of_pages` bigint NOT NULL,
  `book_id` bigint DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `UK_29qtqq9pgixv8kqlt0woj1hyp` (`book_id`),
  CONSTRAINT `FKl1hmgccsvfwcxhem3qw6l7gpm` FOREIGN KEY (`book_id`) REFERENCES `book` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci

51.4.2.2. 

					
package cn.netkiller.domain.demo;

import jakarta.persistence.*;

@Entity
public class Book {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    private String name;

    @OneToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "book_detail")
    private BookDetail bookDetail;
}
					
					
				
					
package cn.netkiller.domain.demo;

import jakarta.persistence.*;

@Entity
public class BookDetail {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;


    private long numberOfPages;


    @OneToOne(cascade = CascadeType.ALL, mappedBy = "bookDetail")
    private Book book;
}
					
					
				
					
CREATE TABLE `book` (
  `id` bigint NOT NULL AUTO_INCREMENT,
  `name` varchar(255) DEFAULT NULL,
  `book_detail` bigint DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `UK_d8im4vqhlm2eo0mj9lwjvib94` (`book_detail`),
  CONSTRAINT `FKagqqxsh6783b9dd9197ow49a5` FOREIGN KEY (`book_detail`) REFERENCES `book_detail` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci

CREATE TABLE `book_detail` (
  `id` bigint NOT NULL AUTO_INCREMENT,
  `number_of_pages` bigint NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci

51.4.2.3. 

					
package cn.netkiller.domain.demo;

import jakarta.persistence.Entity;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.GenerationType;
import jakarta.persistence.Id;

@Entity
public class Users {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    private String name;

}
					
					
				
					
package cn.netkiller.domain.demo;

import jakarta.persistence.Entity;
import jakarta.persistence.Id;
import jakarta.persistence.OneToOne;

@Entity
public class Profile {
    @Id
    @OneToOne
    private Users users;

    private int age;


}					
					
				
					
CREATE TABLE `users` (
  `id` bigint NOT NULL AUTO_INCREMENT,
  `name` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci

CREATE TABLE `profile` (
  `age` int NOT NULL,
  `users_id` bigint NOT NULL,
  PRIMARY KEY (`users_id`),
  CONSTRAINT `FKi6d1noonlpe6oyk6pnwc1q49e` FOREIGN KEY (`users_id`) REFERENCES `users` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci

指定一对一字段名，默认是表名+PK，例如上面的例子 users_id，如果我们希望自定义字段名，可以使用 @JoinColumn(name = "id") 

					
package cn.netkiller.domain.demo;

import jakarta.persistence.Entity;
import jakarta.persistence.Id;
import jakarta.persistence.JoinColumn;
import jakarta.persistence.OneToOne;
import lombok.Data;

@Entity
@Data
public class Profile {
    @Id
    @OneToOne
    @JoinColumn(name = "id")
    private Users users;

    private int age;
    private boolean sex;
}

效果展示

					
CREATE TABLE `profile` (
  `age` int NOT NULL,
  `sex` bit(1) NOT NULL,
  `id` bigint NOT NULL,
  PRIMARY KEY (`id`),
  CONSTRAINT `FK6x079ilawxjrfsljwyyi5ujjq` FOREIGN KEY (`id`) REFERENCES `users` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci

51.4.2.4. does not define an IdClass

如果一对一的关系中，我们希望两端都是用 id 字段，而@OneToOne 一端是对象，必须定义一个 @Id，这时加入 @MapsId 可以解决 does not define an IdClass 错误，这时一段表中没有 @Id 

					
package cn.netkiller.domain.demo;

import jakarta.persistence.*;
import lombok.Data;
import org.hibernate.annotations.Comment;
import org.hibernate.annotations.DynamicInsert;
import org.hibernate.annotations.DynamicUpdate;

@Entity
@Table
@Data
@DynamicInsert
@DynamicUpdate
@Comment("用户表")
public class Users {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    private String username;
    private String password;
    private boolean status;

}

					
				
					
package cn.netkiller.domain.demo;

import jakarta.persistence.Table;
import jakarta.persistence.*;
import lombok.Data;
import org.hibernate.annotations.*;

@Entity
@Table
@Data
@DynamicInsert
@DynamicUpdate
@Comment("用户信息表")
public class Profile {

    @Id
    @Column(name = "id")
    private Long id;

    @MapsId
    @OneToOne
    @JoinColumn(name = "id")
    @OnDelete(action = OnDeleteAction.CASCADE)
    private Users users;

    private int age;
    private boolean sex;
}
					
					
				
					
package cn.netkiller.repository.demo;

import cn.netkiller.domain.demo.Profile;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface TestRepository extends JpaRepository<Profile, Long> {
}

					
				
					
CREATE TABLE `users` (
  `id` bigint NOT NULL AUTO_INCREMENT,
  `password` varchar(255) DEFAULT NULL,
  `status` bit(1) NOT NULL,
  `username` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci COMMENT='用户表'

CREATE TABLE `profile` (
  `id` bigint NOT NULL,
  `age` int NOT NULL,
  `sex` bit(1) NOT NULL,
  PRIMARY KEY (`id`),
  CONSTRAINT `FK6x079ilawxjrfsljwyyi5ujjq` FOREIGN KEY (`id`) REFERENCES `users` (`id`) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci COMMENT='用户信息表'

51.4.2.5. 共享主键

					
package cn.netkiller.domain.demo;

import jakarta.persistence.*;
import lombok.Data;
import org.hibernate.annotations.Comment;
import org.hibernate.annotations.DynamicInsert;
import org.hibernate.annotations.DynamicUpdate;

@Entity
@Table
@Data
@DynamicInsert
@DynamicUpdate
@Comment("用户表")
public class Users {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    private String username;
    private String password;
    private boolean status;

    @OneToOne(mappedBy = "users", cascade = CascadeType.ALL)
    @PrimaryKeyJoinColumn
    private Profile profile;
}
					
					
				
					
package cn.netkiller.domain.demo;

import jakarta.persistence.Table;
import jakarta.persistence.*;
import lombok.Data;
import org.hibernate.annotations.*;

@Entity
@Table
@Data
@DynamicInsert
@DynamicUpdate
@Comment("用户信息表")
public class Profile {

    @Id
    @Column(name = "id")
    private Long id;

    @MapsId
    @OneToOne
    @JoinColumn(name = "id")
    @OnDelete(action = OnDeleteAction.CASCADE)
    private Users users;

    private int age;
    private boolean sex;
}
					
					
				
					
CREATE TABLE `users` (
  `id` bigint NOT NULL AUTO_INCREMENT,
  `password` varchar(255) DEFAULT NULL,
  `status` bit(1) NOT NULL,
  `username` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci COMMENT='用户表'

CREATE TABLE `profile` (
  `id` bigint NOT NULL,
  `age` int NOT NULL,
  `sex` bit(1) NOT NULL,
  PRIMARY KEY (`id`),
  CONSTRAINT `FK6x079ilawxjrfsljwyyi5ujjq` FOREIGN KEY (`id`) REFERENCES `users` (`id`) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci COMMENT='用户信息表'

51.4.2.6. null identifier

@OneToOne 保存提示 null identifier，经过排查需要配置

					
package cn.netkiller.domain;

import jakarta.persistence.CascadeType;
import jakarta.persistence.ForeignKey;
import jakarta.persistence.Table;
import jakarta.persistence.*;
import lombok.Data;
import org.hibernate.annotations.*;

import java.io.Serial;
import java.io.Serializable;
import java.util.Date;

@Entity
@Table
@DynamicUpdate
@DynamicInsert
@Data
@Comment("文生图心里分析")

public class PicturePsychoanalysis implements Serializable {
    @Serial
    public static final long serialVersionUID = 1L;
    
    @Comment("Robert Plutchik 情感轮盘")
    @Column(columnDefinition = "json")
    public String plutchik;
    
    @Id
    @Column(name = "id")
    @Comment("Picture Id 一对一关系")
    private Long id;
    @MapsId
    @OneToOne(cascade = CascadeType.MERGE)
    @JoinColumn(name = "id", insertable = true, updatable = false, columnDefinition = "bigint unsigned", foreignKey = @ForeignKey(name = "picture_id"))
    @OnDelete(action = OnDeleteAction.CASCADE)
    private Picture picture;
    @Comment("负向情绪|中性情绪|正向情绪")
    private String sentiment;
    @Comment("感谢|愉快|抱怨|愤怒|喜爱|厌恶|恐惧|悲伤")
    private String emotion;
    @Lob
    @Basic(fetch = FetchType.LAZY)
    @Column(nullable = true, columnDefinition = "text")
    @Comment("建议回复话术")
    private String replies;
    @Lob
    @Basic(fetch = FetchType.LAZY)
    @Column(nullable = true, columnDefinition = "text")
    @Comment("心里分析")
    private String analysis;
    //    public JSONObject plutchik;
    @Column(insertable = false, updatable = false, columnDefinition = "TIMESTAMP DEFAULT CURRENT_TIMESTAMP")
    @Comment("创建时间")
    private Date ctime;

    @Column(nullable = true, insertable = false, updatable = false, columnDefinition = "TIMESTAMP NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP")
    @Comment("修改时间")
    private Date mtime;
}

讲 @OneToOne 增加 @OneToOne(cascade = CascadeType.MERGE) 参数，如果 CascadeType.ALL 需要改为 CascadeType.MERGE 

					
	@Id
    @Column(name = "id")
    @Comment("Picture Id 一对一关系")
    private Long id;
    @MapsId
    @OneToOne(cascade = CascadeType.MERGE)
    @JoinColumn(name = "id", insertable = true, updatable = false, columnDefinition = "bigint unsigned", foreignKey = @ForeignKey(name = "picture_id"))
    @OnDelete(action = OnDeleteAction.CASCADE)
    private Picture picture;

51.4.3. OneToMany 一对多

我们要实现一个一对多实体关系，ER 图如下

			
    +----------+          +------------+
    | Classes  |          | Student    |
    +----------+          +------------+
    | id       | <---+    | id         |
    | name     |     |    | name       |    
    +----------+     +--o | classes_id |    
                          +------------+

classes 表需要 OneToMany 注解，Student 表需要 ManyToOne 注解，这样就建立起了表与表之间的关系 

			
package cn.netkiller.api.domain.test;

import java.io.Serializable;
import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;

@Entity 
@Table(name="classes") 
public class Classes implements Serializable{
	/**
	 * 
	 */
	private static final long serialVersionUID = -5422905745519948312L;
	@Id 
	@GeneratedValue(strategy=GenerationType.AUTO) 
	private int id; 
	private String name; 
	    
	@OneToMany(cascade=CascadeType.ALL,mappedBy="classes")    
	private Set<Student> students;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public Set<Student> getStudents() {
		return students;
	}

	public void setStudents(Set<Student> students) {
		this.students = students;
	}

	@Override
	public String toString() {
		return "classes [id=" + id + ", name=" + name + ", students=" + students + "]";
	} 
}
			
			
			
package cn.netkiller.api.domain.test;

import java.io.Serializable;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

@Entity
@Table(name = "student")
public class Student implements Serializable{
	/**
	 * 
	 */
	private static final long serialVersionUID = 6737037465677800326L;
	@Id
	@GeneratedValue(strategy = GenerationType.AUTO)
	private int id;
	private String name;

	// 若有多个cascade，可以是：{CascadeType.PERSIST,CascadeType.MERGE}
	@ManyToOne(cascade = { CascadeType.ALL })
	@JoinColumn(name = "classes_id") 
	private Classes classes;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public Classes getClasses() {
		return classes;
	}

	public void setClasses(Classes classes) {
		this.classes = classes;
	}

	@Override
	public String toString() {
		return "Student [id=" + id + ", name=" + name + ", classes=" + classes + "]";
	}

}

最终 SQL 表如下

			
CREATE TABLE `classes` (
	`id` INT(11) NOT NULL AUTO_INCREMENT,
	`name` VARCHAR(255) NULL DEFAULT NULL,
	PRIMARY KEY (`id`)
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB;	
			
CREATE TABLE `student` (
	`id` INT(11) NOT NULL AUTO_INCREMENT,
	`name` VARCHAR(255) NULL DEFAULT NULL,
	`class_id` INT(11) NULL DEFAULT NULL,
	PRIMARY KEY (`id`),
	INDEX `FKnsl7w2nw6o6eq53hqlxfcijpm` (`class_id`),
	CONSTRAINT `FKnsl7w2nw6o6eq53hqlxfcijpm` FOREIGN KEY (`class_id`) REFERENCES `classes` (`id`)
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB;
			
			
			
      Classes classes=new Classes(); 
      classes.setName("One"); 
        
      Student st1=new Student(); 
      st1.setSname("jason"); 
      st1.setClasses(classes); 
      studentRepostitory.save(st1); 
        
      Student st2=new Student(); 
      st2.setSname("neo"); 
      st2.setClasses(classes); 
      studentRepostitory.save(st2);

51.4.4. ManyToMany 多对多

用户与角色就是一个多对多的关系，多对多是需要中间表做关联的。所以我方需要一个 user_has_role 表。

			
    +----------+          +---------------+            +--------+
    | users    |          | user_has_role |            | role   |
    +----------+          +---------------+            +--------+
    | id       | <------o | user_id       |      /---> | id     |
    | name     |          | role_id       | o---+      | name   |
    | password |          |               |            |        |
    +----------+          +---------------+            +--------+

创建 User 表

			
package cn.netkiller.api.domain.test;

import java.io.Serializable;
import java.util.Set;

import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.Table;
import javax.persistence.JoinColumn;

@Entity
@Table(name = "users")
public class Users implements Serializable {
	/**
	 * 
	 */
	private static final long serialVersionUID = -2480194112597046349L;
	@Id
	@GeneratedValue(strategy = GenerationType.AUTO)
	private int id;
	private String name;
	private String password;

	@ManyToMany(fetch = FetchType.EAGER)
	@JoinTable(name = "user_has_role", joinColumns = { @JoinColumn(name = "user_id", referencedColumnName = "id") }, inverseJoinColumns = { @JoinColumn(name = "role_id", referencedColumnName = "id") })
	private Set<Roles> roles;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

	public Set<Roles> getRoles() {
		return roles;
	}

	public void setRoles(Set<Roles> roles) {
		this.roles = roles;
	}

	@Override
	public String toString() {
		return "Users [id=" + id + ", name=" + name + ", password=" + password + ", roles=" + roles + "]";
	}

}

创建 Role 表

			
package cn.netkiller.api.domain.test;

import java.io.Serializable;
import java.util.Set;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.ManyToMany;
import javax.persistence.Table;

@Entity
@Table(name = "roles")
public class Roles implements Serializable {
	private static final long serialVersionUID = 6737037465677800326L;
	@Id
	@GeneratedValue(strategy = GenerationType.AUTO)
	private int id;
	private String name;
	@ManyToMany(mappedBy = "roles")
	private Set<Users> users;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public Set<Users> getUsers() {
		return users;
	}

	public void setUsers(Set<Users> users) {
		this.users = users;
	}

	@Override
	public String toString() {
		return "Roles [id=" + id + ", name=" + name + ", users=" + users + "]";
	}

}

最终产生数据库表如下

			
CREATE TABLE `users` (
	`id` INT(11) NOT NULL AUTO_INCREMENT,
	`name` VARCHAR(255) NULL DEFAULT NULL,
	`password` VARCHAR(255) NULL DEFAULT NULL,
	PRIMARY KEY (`id`)
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB;	

CREATE TABLE `roles` (
	`id` INT(11) NOT NULL AUTO_INCREMENT,
	`name` VARCHAR(255) NULL DEFAULT NULL,
	PRIMARY KEY (`id`)
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB;
			
CREATE TABLE `user_has_role` (
	`user_id` INT(11) NOT NULL,
	`role_id` INT(11) NOT NULL,
	PRIMARY KEY (`user_id`, `role_id`),
	INDEX `FKsvvq61v3koh04fycopbjx72hj` (`role_id`),
	CONSTRAINT `FK2dl1ftxlkldulcp934i3125qo` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`),
	CONSTRAINT `FKsvvq61v3koh04fycopbjx72hj` FOREIGN KEY (`role_id`) REFERENCES `roles` (`id`)
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB;

51.4.5. 外键级联删除

orphanRemoval 是 JPA 定义，并不是数据库原生

					
    @Id
    @OneToOne(cascade = CascadeType.ALL, orphanRemoval = true)
    @JoinColumn(name = "id", foreignKey = @ForeignKey(name = "picture_id"))
    private Picture picture;

orphanRemoval = true 可以实现数据级联删除

			
package cn.netkiller.api.domain;

import java.io.Serializable;
import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Table;

import com.fasterxml.jackson.annotation.JsonIgnore;

@Entity
@Table(name = "member")
public class Member implements Serializable {
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	@Column(name = "id", unique = true, nullable = false, insertable = true, updatable = false)
	private int id;

	private String name;
	private String sex;
	private int age;
	private String wechat;

	@Column(unique = true)
	private String mobile;
	private String picture;
	private String ipAddress;

	@JsonIgnore
	@OneToMany(cascade = CascadeType.ALL, orphanRemoval = true, mappedBy = "member")
	private Set<Comment> comment;
	@JsonIgnore
	@OneToMany(cascade = CascadeType.ALL, orphanRemoval = true, mappedBy = "member")
	private Set<StatisticsHistory> statisticsHistory;

	public Member() {
	}

	public Member(int id) {
		this.id = id;
	}

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getSex() {
		return sex;
	}

	public void setSex(String sex) {
		this.sex = sex;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	public String getWechat() {
		return wechat;
	}

	public void setWechat(String wechat) {
		this.wechat = wechat;
	}

	public String getMobile() {
		return mobile;
	}

	public void setMobile(String mobile) {
		this.mobile = mobile;
	}

	public String getPicture() {
		return picture;
	}

	public void setPicture(String picture) {
		this.picture = picture;
	}

	public String getIpAddress() {
		return ipAddress;
	}

	public void setIpAddress(String ipAddress) {
		this.ipAddress = ipAddress;
	}

	@Override
	public String toString() {
		return "Member [id=" + id + ", name=" + name + ", sex=" + sex + ", age=" + age + ", wechat=" + wechat + ", mobile=" + mobile + ", picture=" + picture + ", ipAddress=" + ipAddress + "]";
	}

}

51.4.6. 外键级联操作

cascade 属性： 指定级联操作的行为(可多选)

				
CascadeType.PERSIST：级联新增（又称级联保存）：对A对象保存时也会对B对象进行保存。并且，只有A类新增时，会级联B对象新增。若B对象在数据库存在则抛异常。对应EntityManager的presist方法。
CascadeType.MERGE：级联合并（级联更新）：指A类新增或者变化，会级联B对象（新增或者变化）。对应EntityManager的merge方法。
CascadeType.REMOVE：级联删除：只有A类删除时，会级联删除B类,即在设置的那一端进行删除时，另一端才会级联删除。对应EntityManager的remove方法。
CascadeType.REFRESH：级联刷新：获取A对象时也重新获取最新的B对象。对EntityManager的refresh(object)方法。即会重新查询数据库里的最新数据（用的比较少）
CascadeType.DETACH：级联分离。
CascadeType.ALL：级联所有操作。

51.4.6.1. CascadeType.PERSIST

					
@OneToMany(mappedBy = "boss", cascade = CascadeType.PERSIST)  
private List<Staff> staffList;

51.4.6.2. CascadeType.REMOVE

					
@OneToMany(mappedBy = "boss", cascade = CascadeType.REMOVE)  
private List<Staff> staffList;

51.4.6.3. CascadeType.MERGE

				
package cn.netkiller.domain;

import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.annotation.JsonIgnore;
import jakarta.persistence.*;
import lombok.Data;
import org.hibernate.annotations.Comment;
import org.hibernate.annotations.DynamicInsert;
import org.hibernate.annotations.DynamicUpdate;
import org.springframework.format.annotation.DateTimeFormat;

import java.io.Serial;
import java.io.Serializable;
import java.util.Date;

@Entity
@Table
@Data
@DynamicUpdate
@DynamicInsert
@Comment("客户信息表")
public class Consumer implements Serializable {
    @Serial
    public static final long serialVersionUID = -1L;

    @Id
//    @GeneratedValue(strategy = GenerationType.IDENTITY)
//    @Column(name = "id", unique = true, nullable = false, insertable = false, updatable = false, columnDefinition = "int unsigned")
    @Comment("唯一ID")
//    @Column(name = "id", nullable = false, columnDefinition = "int unsigned")
    private Integer id;

    //    CascadeType.MERGE 集联更新，会更新外键表数据，覆盖
    @OneToOne(cascade = CascadeType.MERGE, optional = false)
    @MapsId
    @JoinColumn(name = "id", nullable = false, insertable = true, updatable = false, columnDefinition = "int unsigned", foreignKey = @ForeignKey(name = "device_id"))
    @JsonIgnore
    private Device device;

    @Comment("姓名")
    @Column(length = 8)
    private String name;
    @Comment("昵称")
    @Column(length = 16)
    private String nickname;
    @Comment("头像")
    private String avatar;
    @Comment("性别")
    private Boolean gender;
    @Comment("年龄")
    private Integer age;
    @Comment("生日")
    @JsonFormat(pattern = "yyyy-MM-dd")
    @Temporal(TemporalType.DATE)
    @DateTimeFormat(pattern = "yyyy-MM-dd")
    private Date birthday;
    @Comment("地址")
    private String address;
    @Comment("电话")
    @Column(length = 15)
    private String mobile;

    @Column(insertable = false, updatable = false, columnDefinition = "TIMESTAMP DEFAULT CURRENT_TIMESTAMP")
    @Comment("创建时间")
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")
//    @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")
    private Date ctime;

    @Column(nullable = true, insertable = false, updatable = false, columnDefinition = "TIMESTAMP NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP")
    @Comment("修改时间")
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")
//    @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")
    private Date mtime;

    public Consumer() {
    }

}

				
				
				
package cn.netkiller.domain;

import com.fasterxml.jackson.annotation.JsonFormat;
import jakarta.persistence.*;
import lombok.Data;
import org.hibernate.annotations.Comment;
import org.hibernate.annotations.DynamicInsert;
import org.hibernate.annotations.DynamicUpdate;
import org.springframework.data.annotation.CreatedDate;
import org.springframework.format.annotation.DateTimeFormat;

import java.io.Serial;
import java.io.Serializable;
import java.util.Date;

@Entity
@Table(uniqueConstraints = {@UniqueConstraint(columnNames = {"name", "business_id"})}
//        indexes = {
//        @Index(name = "key_device_unique", columnList = "name"),
//        @Index(name = "key_device_unique", columnList = "business_id")
//}
)
@DynamicUpdate
@DynamicInsert
@Data
//@Builder
@Comment("设备表")
public class Device implements Serializable {
    @Serial
    public static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", unique = true, nullable = false, insertable = false, updatable = false, columnDefinition = "int unsigned")
    @Comment("主键")
    private Integer id;

    @Column(nullable = false, length = 32)
    @Comment("设备名称")
    private String name;

    @Column(unique = true, nullable = false, insertable = true, updatable = false, length = 32)
    @Comment("序列号")
    private String sn;

    @Comment("型号")
    @Column(length = 16)
    private String model;
    @Comment("固件版本")
    @Column(length = 16)
    private String fireware;
    @Comment("软件版本")
    @Column(length = 16)
    private String version;

    @Column(columnDefinition = "int unsigned")
    @Comment("存储容量")
    private Integer capacity = null;

    @Column(columnDefinition = "int unsigned")
    @Comment("可用容量")
    private Integer available;

    @Column(columnDefinition = "int unsigned")
    @Comment("内存容量")
    private Integer memory;

    @Comment("移动网络提供商")
    @Column(columnDefinition = "enum('中国移动','中国电信','中国联通','其他') DEFAULT NULL")
    private String provider;

    @Comment("IMEI")
    @Column(length = 15)
    private String imei;

    @Comment("MEID")
    @Column(length = 15)
    private String meid;

    @Comment("ICCID")
    @Column(length = 20)
    private String iccid;

    @Comment("wlan 无线 mac 地址")
    @Column(length = 17)
    private String wlan;
    @Column(length = 17)
    @Comment("蓝牙 mac 地址")
    private String bluetooth;

    @Comment("品牌")
    private String brand;

    @Comment("CPU")
    private String cpu;

    @Comment("设备驱动")
    private String device;

    @Comment("显示屏")
    private String display;

    @Comment("设备标识")
    private String fingerprint;

    @Comment("硬件")
    private String hardware;

    @Comment("制造商")
    private String manufacturer;

    @Comment("产品")
    private String product;

    @Column(columnDefinition = "enum('Y','N') DEFAULT 'N'")
    @Comment("设备状态，正常=Y，其他=N")
    private String status;

    @Comment("设备状态原因")
    @Column(columnDefinition = "enum('未激活','激活','充值','正常','禁用','冻结') DEFAULT '正常'")
    private String reason;

    @Comment("设备状态描述")
    private String description;

    @CreatedDate
    @Column(nullable = true, insertable = true, updatable = true)
    @Temporal(TemporalType.TIMESTAMP)
    @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")
    @Comment("访问时间")
    private Date atime;

    @ManyToOne
    @JoinColumn(name = "business_id")
    private Business business;

    @Column(insertable = false, updatable = false, columnDefinition = "TIMESTAMP DEFAULT CURRENT_TIMESTAMP")
    //    @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")
    @Comment("创建时间")
    private Date ctime;

    @Column(nullable = true, insertable = false, updatable = false, columnDefinition = "TIMESTAMP NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP")
    //    @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")
    @Comment("修改时间")
    private Date mtime;

    public Device() {

    }

}
				
				
				
    @Transactional
    public Optional<Consumer> update(String deviceName, Consumer consumer) {
        Device device = new Device();
        device.setId(consumer.getId());
        device.setName(deviceName);
        consumer.setDevice(device);
        log.debug(consumer.toString());
        consumer = consumerRepository.save(consumer);
        return Optional.ofNullable(consumer);
    }

向 Consumer 表中增加数据，Device 表受到影响，会修改里面的数据。这就是 CascadeType.MERGE 作用，如果不想影响 Device 数据，改为 CascadeType.PERSIST

				
@OneToOne(cascade = CascadeType.MERGE, optional = false)

51.4.6.4. MySQL ON DELETE CASCADE

@OnDelete(action = OnDeleteAction.CASCADE)

					
package cn.netkiller.domain;

import jakarta.persistence.*;
import lombok.Data;
import org.hibernate.annotations.Comment;
import org.hibernate.annotations.DynamicUpdate;
import org.hibernate.annotations.OnDelete;
import org.hibernate.annotations.OnDeleteAction;

import java.io.Serial;
import java.io.Serializable;
import java.util.Date;

@Entity
@Table
@DynamicUpdate
@Data
@Comment("文生图心里分析")
public class PicturePsychoanalysis implements Serializable {
    @Serial
    public static final long serialVersionUID = 1L;

    @Id
    @OneToOne()
    @JoinColumn(name = "id", foreignKey = @ForeignKey(name = "picture_id"))
    @OnDelete(action = OnDeleteAction.CASCADE)
    private Picture picture;

//    @Column(unique = true, nullable = false, insertable = true, updatable = false)
//    @Comment("会话")
//    private String session;

    @Comment("负向情绪|中性情绪|正向情绪")
    private String sentiment;

    @Comment("感谢|愉快|抱怨|愤怒|喜爱|厌恶|恐惧|悲伤")
    private String emotion;

    @Lob
    @Basic(fetch = FetchType.LAZY)
    @Column(nullable = true, columnDefinition = "text")
    @Comment("建议回复话术")
    private String replies;

    @Lob
    @Basic(fetch = FetchType.LAZY)
    @Column(nullable = true, columnDefinition = "text")
    @Comment("心里分析")
    private String analysis;

    @Column(insertable = false, updatable = false, columnDefinition = "TIMESTAMP DEFAULT CURRENT_TIMESTAMP")
    @Comment("创建时间")
    private Date ctime;

    @Column(nullable = true, insertable = false, updatable = false, columnDefinition = "TIMESTAMP NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP")
    @Comment("修改时间")
    private Date mtime;
}
					
					
				

					
CREATE TABLE `picture_psychoanalysis` (
  `analysis` text COMMENT '心里分析',
  `ctime` timestamp NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
  `emotion` varchar(255) DEFAULT NULL COMMENT '感谢|愉快|抱怨|愤怒|喜爱|厌恶|恐惧|悲伤',
  `mtime` timestamp NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP COMMENT '修改时间',
  `replies` text COMMENT '建议回复话术',
  `sentiment` varchar(255) DEFAULT NULL COMMENT '负向情绪|中性情绪|正向情绪',
  `id` bigint unsigned NOT NULL,
  PRIMARY KEY (`id`),
  CONSTRAINT `picture_id` FOREIGN KEY (`id`) REFERENCES `picture` (`id`) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci COMMENT='文生图心里分析'

51.4.7. @JoinTable

				
@JoinTable(name = "table")				
				
			
				
@OneToMany(cascade = CascadeType.ALL)
@JoinTable
private List<UserProfile> userProfile;				
				
			
				
@JoinTable(name = "cust_user",
    joinColumns = @JoinColumn(name = "user_id", referencedColumnName = "id")
)		
				
			
				
@JoinTable(name = "cust_user",
    inverseJoinColumns = @JoinColumn(name = "user_ext_id", referencedColumnName = "id")
)			
				
			
				
@JoinTable(name = "cust_user",
    joinColumns = @JoinColumn(name = "user_id", referencedColumnName = "id"),
    inverseJoinColumns = @JoinColumn(name = "user_ext_id", referencedColumnName = "id"),
    uniqueConstraints = {
        @UniqueConstraint(name = "unique_user_id", columnNames = {"user_id"}),
        @UniqueConstraint(name = "unique_user_ext_id", columnNames = {"user_ext_id"})
    }
)

51.4.7.1. 多对多实例

					
package cn.netkiller.domain;

import jakarta.persistence.*;
import lombok.Data;

import java.io.Serializable;

@Entity
@Table
@Data
public class Consumer implements Serializable {
    public static final long serialVersionUID = 7998903421265538801L;
    public String firstName;
    public String lastName;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", unique = true, nullable = false, insertable = false, updatable = false, columnDefinition = "int unsigned")
    public Integer id;

    @OneToOne(cascade = CascadeType.ALL, orphanRemoval = true)
    @JoinTable(name = "consumer_has_device",
            joinColumns =
                    {@JoinColumn(name = "consumer_id", referencedColumnName = "id")},
            inverseJoinColumns =
                    {@JoinColumn(name = "device_id", referencedColumnName = "id")})
    private Device device;

    public Consumer() {
    }

}

					
				
					
package cn.netkiller.domain;

import jakarta.persistence.*;
import lombok.Data;
import org.hibernate.annotations.Comment;
import org.hibernate.annotations.DynamicUpdate;

import java.io.Serial;
import java.io.Serializable;
import java.util.Date;

@Entity
@Table
@DynamicUpdate
@Data
@Comment("设备表")
public class Device implements Serializable {
    @Serial
    public static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", unique = true, nullable = false, insertable = false, updatable = false, columnDefinition = "int unsigned")
    @Comment("主键")
    private Integer id;

    @Comment("设备名称")
    private String name;

    @Comment("型号")
    private String model;
    @Comment("版本")
    private String fireware;
    @Comment("版本")
    private String version;

    @Column(unique = true, nullable = false, insertable = true, updatable = false)
    @Comment("序列号")
    private String sn;
    @Comment("ip")
    private String ip;

    @Comment("mac")
    private String mac;

    @Temporal(TemporalType.TIMESTAMP)
    @Comment("最后一次登陆时间")
    private Date lastTime;

    @Column(columnDefinition = "enum('Y','N') DEFAULT 'N'")
    @Comment("设备状态")
    private boolean status;

    @Column(insertable = false, updatable = false, columnDefinition = "TIMESTAMP DEFAULT CURRENT_TIMESTAMP")
    @Comment("创建时间")
    private Date ctime;

    @Column(nullable = true, insertable = false, updatable = false, columnDefinition = "TIMESTAMP NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP")
    @Comment("修改时间")
    private Date mtime;
}

					
				
					
CREATE TABLE `consumer` (
  `id` int unsigned NOT NULL AUTO_INCREMENT,
  `first_name` varchar(255) DEFAULT NULL,
  `last_name` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci

CREATE TABLE `device` (
  `id` int unsigned NOT NULL AUTO_INCREMENT COMMENT '主键',
  `ctime` timestamp NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
  `fireware` varchar(255) DEFAULT NULL COMMENT '版本',
  `ip` varchar(255) DEFAULT NULL COMMENT 'ip',
  `last_time` datetime(6) DEFAULT NULL COMMENT '最后一次登陆时间',
  `mac` varchar(255) DEFAULT NULL COMMENT 'mac',
  `model` varchar(255) DEFAULT NULL COMMENT '型号',
  `mtime` timestamp NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP COMMENT '修改时间',
  `name` varchar(255) DEFAULT NULL COMMENT '设备名称',
  `sn` varchar(255) NOT NULL COMMENT '序列号',
  `status` enum('Y','N') DEFAULT 'N' COMMENT '设备状态',
  `version` varchar(255) DEFAULT NULL COMMENT '版本',
  PRIMARY KEY (`id`),
  UNIQUE KEY `UK_bg7pgyvfwv0q65tmquumxff3d` (`sn`)
) ENGINE=InnoDB AUTO_INCREMENT=12 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci COMMENT='设备表'

CREATE TABLE `consumer_has_device` (
  `device_id` int unsigned DEFAULT NULL,
  `consumer_id` int unsigned NOT NULL,
  PRIMARY KEY (`consumer_id`),
  UNIQUE KEY `UK_ibck20j1s6ch97lncg99uvpgh` (`device_id`),
  CONSTRAINT `FKcottusf6sx3bnouahp29vjdwk` FOREIGN KEY (`device_id`) REFERENCES `device` (`id`),
  CONSTRAINT `FKq7u4eyw8pmfkwg4yymjljx8ra` FOREIGN KEY (`consumer_id`) REFERENCES `consumer` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci

51.4.8. @OrderBy

				
// JPA 默认根据 Student 的 ID 主键对 studentList 集合数据进行递增排序
@OneToMany(cascade = CascadeType.ALL)
@OrderBy
private List<Student> studentList;
 
// 手动指定 id 字段的排序方式，ASC 递增排序，DESC 递减排序
@OneToMany(cascade = CascadeType.ALL)
@OrderBy("id desc")
private List<Student> studentList;
 
// 手动指定按照 salary 属性进行递减排序
@OneToMany(cascade = CascadeType.ALL)
@OrderBy("salary desc")
private List<Student> studentList;
 
// 手动指定按照多个属性进行排序
// 下面将根据 sex 和 salay 进行递增排序
@OneToMany(cascade = CascadeType.ALL)
@OrderBy("sex,salary")
private List<Student> studentList;
 
// 下面将根据 sex 递增排序，salary 递增排序
@OneToMany(cascade = CascadeType.ALL)
@OrderBy("sex asc,salary asc")
private List<Student> studentList;
 
// 下面将根据 sex 递增排序，salary 递减排序
@OneToMany(cascade = CascadeType.ALL)
@OrderBy("sex asc,salary desc")
private List<Student> studentList;

51.4.9. @JsonIgnoreProperties

			
@Entity
public class Subarea {

  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private long id;

  @OneToMany
  @JsonIgnoreProperties(value = {"subarea"})
  @JoinColumn(name = "subarea_id")
  private List<SubareaSet> subareaSetList;

}

@Entity
public class SubareaSet {
  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private long id;
  
  @ManyToOne
  @JsonIgnoreProperties(value = {"subareaSetList"})
  private Subarea subarea;
}
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51.3. 映射集合属性 起始页 51.5. 索引