Hibernate（annotation映射）

最新推荐文章于 2025-07-28 23:27:29 发布

andyLiu8571

最新推荐文章于 2025-07-28 23:27:29 发布

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文章标签： hibernate string table class

本文链接：https://blog.youkuaiyun.com/andyLiu8571/article/details/7729717

本文详细介绍了Hibernate中实现一对多关系的多种方式，包括基于外键关联、基于连接表的单向及双向一对多映射，并提供了具体的Java类代码示例。

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Hibernate入门

一、基于外键关联的一对多映射（annotation）

1.1一的代码

@Entity

@Table(name="tb_cclass")

publicclass Classes {

@Id

@GeneratedValue(strategy=GenerationType.IDENTITY)

privateintid;

@Column(name="name")

private String name;

/**

* oneToMany默认产生连接表，如果用JoinColumn表示外键关联，不产生连接表

@OneToMany

@JoinColumn(name="classId")

private Set<Student> students;

publicint getId() {

returnid;

}

publicvoid setId(int id) {

this.id = id;

}

public String getName() {

returnname;

}

publicvoid setName(String name) {

this.name = name;

}

public Set<Student> getStudents() {

returnstudents;

}

publicvoid setStudents(Set<Student> students) {

this.students = students;

}

1.2 多的代码

@Entity

@Table(name="tb_cstudent")

publicclass Student {

@Id

@GeneratedValue

privateintid;

@Column(name="name")

private String name;

@Column(name="age")

privateintage;

publicint getId() {

returnid;

}

publicvoid setId(int id) {

this.id = id;

}

public String getName() {

returnname;

}

publicvoid setName(String name) {

this.name = name;

}

publicint getAge() {

returnage;

}

publicvoid setAge(int age) {

this.age = age;

}

二、基于连接表的单向一对多

2.1一端的映射

@Entity

@Table(name="tb_cclass")

publicclass Classes {

@Id

@GeneratedValue(strategy=GenerationType.IDENTITY)

privateintid;

@Column(name="name")

private String name;

/**

* oneToMany默认产生连接表*/

@OneToMany

@JoinTable(name="tb_classes_student",

joinColumns=@JoinColumn(name="class_id"),

inverseJoinColumns=@JoinColumn(name="student_id"))

private Set<Student> students;

publicint getId() {

returnid;

}

publicvoid setId(int id) {

this.id = id;

}

public String getName() {

returnname;

}

publicvoid setName(String name) {

this.name = name;

}

public Set<Student> getStudents() {

returnstudents;

}

publicvoid setStudents(Set<Student> students) {

this.students = students;

}

三、基于连接表的双向一对多，关系有多的一方来维护

3.1一方

@Entity

@Table(name="tb_cclass2")

publicclass Classes2 {

@Id

@GeneratedValue(strategy=GenerationType.IDENTITY)

privateintid;

@Column(name="name")

private String name;

/**

* oneToMany默认产生连接表，如果用JoinColumn表示外键关联，不产生连接表

@OneToMany(mappedBy="classes2")

private Set<Student2> students;

publicint getId() {

returnid;

}

publicvoid setId(int id) {

this.id = id;

}

public String getName() {

returnname;

}

publicvoid setName(String name) {

this.name = name;

}

public Set<Student2> getStudents() {

returnstudents;

}

publicvoid setStudents(Set<Student2> students) {

this.students = students;

}

3.2多方

@Entity

@Table(name="tb_cstudent2")

publicclass Student2 {

@Id

@GeneratedValue

privateintid;

@Column(name="name")

private String name;

@Column(name="age")

privateintage;

@ManyToOne

@JoinTable(name="tb_classes_student2",

joinColumns=@JoinColumn(name="student_id"),

inverseJoinColumns=@JoinColumn(name="class_id"))

private Classes2 classes2;

publicint getId() {

returnid;

}

publicvoid setId(int id) {

this.id = id;

}

public String getName() {

returnname;

}

publicvoid setName(String name) {

this.name = name;

}

publicint getAge() {

returnage;

}

publicvoid setAge(int age) {

this.age = age;

}