Hibernate (7) component ing and multi-to-one ing, hibernate multiple-to-one

Hibernate (7) component ing and multi-to-one ing, hibernate multiple-to-one

I. Component ing

Configure component ing with annotations:

Husband Is A ing Class. wife is a part of this class (the property cannot be the same as the property in husband. Do not write the Entity annotation or have a primary key)

Husband class: (add annotation @ Embedded on the getWife () method)

package cn.orlion.hibernate.model;import javax.persistence.Embedded;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;@Entitypublic class Husband {        private int id;        private String name;        private Wife wife;        @Id    @GeneratedValue    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;    }    @Embedded    public Wife getWife() {        return wife;    }    public void setWife(Wife wife) {        this.wife = wife;    }}

Wife class:

package cn.orlion.hibernate.model;public class Wife {        private String wifename;    public String getWifename() {        return wifename;    }    public void setWifename(String wifename) {        this.wifename = wifename;    }}

Table creation statement:

create table Husband (        id integer not null auto_increment,        name varchar(255),        wifename varchar(255),        primary key (id)    )

 

2. Multi-to-one ing

1. Multi-to-one unidirectional ing

Annotation mode configuration: (A group has multiple users, each user corresponds to a group, and the user is multiple parties, and the group is one)

Group class:

Package cn. orlion. hibernate. model; import javax. persistence. entity; import javax. persistence. generatedValue; import javax. persistence. id; import javax. persistence. table;/** a group has multiple users. Each user corresponds to a group, with multiple users and one group */@ Entity @ Table (name = "t_group ") public class Group {private int id; private String name; @ Id @ GeneratedValue 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 ;}}

 

User class:

package cn.orlion.hibernate.model;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.ManyToOne;import javax.persistence.Table;@Entity@Table(name="t_user")public class User {    private int id;        private String name;        private Group group;    @Id    @GeneratedValue    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;    }    @ManyToOne    public Group getGroup() {        return group;    }    public void setGroup(Group group) {        this.group = group;    }}

 

SQL statement generated by hibernate:

create table t_group (        id integer not null auto_increment,        name varchar(255),        primary key (id)    )create table t_user (        id integer not null auto_increment,        name varchar(255),        group_id integer,        primary key (id)    )alter table t_user         add constraint FK_e5f24mh6aryt9hsy99oydps6g         foreign key (group_id)         references t_group (id)