Hibernate之关系映射的两种方式（xml映射、annotation注解映射）

本文列出了两种关系映射包括一对一和一对多（多对一），并且列出了两种方式（xml映射和annotation注解映射）分别对一对一和一对多的代码，关键地方标有注释解释。可供初学者参考。

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主键关系映射代码之一对一##

一个学生对应一条登录信息（用户名、密码），一条登录信息对于一个学生

一.xml文件映射

1.在Student类中加入一个对方类型的属性，即登录信息类的实例。

package com.ffy.studentmanage;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.PrimaryKeyJoinColumn;
import javax.persistence.Table;
public class Student {
private int id;
private int sid;
private String firstName;
private String lastName;
private String gender;
private String phone;
private String email;
private String dateOfBirth;
private double height=160;
private int studentStatusID;

//在student表中加入StudentLogin属性
private StudentLogin studentLogin;

public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public int getSid() {
return sid;
}
public void setSid(int sid) {
this.sid = sid;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastname() {
return lastName;
}
public void setLastname(String lastName) {
this.lastName = lastName;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getDateOfBirth() {
return dateOfBirth;
}
public void setDateOfBirth(String dateOfBirth) {
this.dateOfBirth = dateOfBirth;
}
public double getHeight() {
return height;
}
public void setHeight(double height) {
this.height = height;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public int getStudentStatusID() {
return studentStatusID;
}
public void setStudentStatusID(int studentStatusID) {
this.studentStatusID = studentStatusID;
}

public StudentLogin getStudentLogin() {
return studentLogin;
}
public void setStudentLogin(StudentLogin studentLogin) {
this.studentLogin = studentLogin;
}
public String toString(){
return this.id+":"+this.lastName+this.firstName+this.gender+":"+this.phone+":"+this.email+";username"+studentLogin.getUsername()+";password:"+studentLogin.getPassword();
}
}

2.配置student.hbm.xml,基本属性配置方法不变，StudentLogin的配置如下。

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="com.ffy.studentmanage.Student" table="student">
<id name="id" column="id">
<generator class="assigned"></generator>
</id>
<property name="sid" column="sid"></property>
<property name="firstName" column="firstname"></property>
<property name="lastName" column="lastname"></property>
<property name="gender" column="gender"></property>
<property name="phone" column="phone"></property>
<property name="email" column="email"></property>
<property name="dateOfBirth" column="date_of_birth"></property>
<property name="studentStatusID" column="student_status_id"></property>
<property name="height" column="height"></property>
//对方的属性的映射，name属性为，Student的studentLogin属性，class为对方类，意味将studentLogin属性与studentLogin类建立一对一的映射关系
<one-to-one name="studentLogin" class="com.ffy.studentmanage.StudentLogin" cascade="all"></one-to-one>
</class>
</hibernate-mapping>

3.在hibernate.cfg.xml注册student.hbm.xml文件

<mapping resource="StudentLogin.hbm.xml"/>

二.annotation注解映射

1.在hibernate.cfg.xml注册StudentLogin类

<mapping class="com.ffy.studentmanage.StudentLogin"/>

2.在Student中添加注解

package com.ffy.studentmanage;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.PrimaryKeyJoinColumn;
import javax.persistence.Table;
@Entity
@Table(name="student")
public class Student {
@Id
@Column(name="id")
private int id;
@Column(name="sid")
private int sid;
@Column(name="firstname")
private String firstName;
@Column(name="lastname")
private String lastName;
@Column(name="gender")
private String gender;
@Column(name="phone")
private String phone;
@Column(name="email")
private String email;
@Column(name="date_of_birth")
private String dateOfBirth;
@Column(name="height")
private double height=160;
@Column(name="student_status_id")
private int studentStatusID;

//在student表中加入StudentLogin属性，并标注为一对一属性
@OneToOne
@PrimaryKeyJoinColumn
private StudentLogin studentLogin;

public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public int getSid() {
return sid;
}
public void setSid(int sid) {
this.sid = sid;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastname() {
return lastName;
}
public void setLastname(String lastName) {
this.lastName = lastName;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getDateOfBirth() {
return dateOfBirth;
}
public void setDateOfBirth(String dateOfBirth) {
this.dateOfBirth = dateOfBirth;
}
public double getHeight() {
return height;
}
public void setHeight(double height) {
this.height = height;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public int getStudentStatusID() {
return studentStatusID;
}
public void setStudentStatusID(int studentStatusID) {
this.studentStatusID = studentStatusID;
}

public StudentLogin getStudentLogin() {
return studentLogin;
}
public void setStudentLogin(StudentLogin studentLogin) {
this.studentLogin = studentLogin;
}
public String toString(){
return this.id+":"+this.lastName+this.firstName+this.gender+":"+this.phone+":"+this.email+";username"+studentLogin.getUsername()+";password:"+studentLogin.getPassword();
}
}

主键关系映射代码之多对一（一对多）##

一个学生对应一条状态，一条状态对应多个学生

一.xml文件映射

多方代码#

1.在Student类（多的那方）中加入一个对方类型的属性，即登录信息类的实例。

@Table(name="student")
public class Student {
private int id;
private int sid;
private String firstName;
private String lastName;
private String gender;
private String phone;
private String email;
private String dateOfBirth;
private double height=160;

//多的一方，加入对方的一个类的属性。一个学生对于一个状态。
private StudentStatus status;

private StudentLogin studentLogin;

public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public int getSid() {
return sid;
}
public void setSid(int sid) {
this.sid = sid;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastname() {
return lastName;
}
public void setLastname(String lastName) {
this.lastName = lastName;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getDateOfBirth() {
return dateOfBirth;
}
public void setDateOfBirth(String dateOfBirth) {
this.dateOfBirth = dateOfBirth;
}
public double getHeight() {
return height;
}
public void setHeight(double height) {
this.height = height;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}

public StudentStatus getStatus() {
return status;
}
public void setStatus(StudentStatus status) {
this.status = status;
}
public StudentLogin getStudentLogin() {
return studentLogin;
}
public void setStudentLogin(StudentLogin studentLogin) {
this.studentLogin = studentLogin;
}
public String toString(){
return this.id+":"+this.lastName+this.firstName+this.gender+":"+this.phone+":"+this.email+";username"+studentLogin.getUsername()+";password:"+studentLogin.getPassword();
}
}

2.配置student.hbm.xml,基本属性配置方法不变，StudentStatus的配置如下。

<class name="com.ffy.studentmanage.Student" table="student">
<id name="id" column="id">
<generator class="assigned"></generator>
</id>
<property name="sid" column="sid"></property>
<property name="firstName" column="firstname"></property>
<property name="lastName" column="lastname"></property>
<property name="gender" column="gender"></property>
<property name="phone" column="phone"></property>
<property name="email" column="email"></property>
<property name="dateOfBirth" column="date_of_birth"></property>
<property name="studentStatusID" column="student_status_id"></property>
<property name="height" column="height"></property>
<one-to-one name="studentLogin" class="com.ffy.studentmanage.StudentLogin" cascade="all"></one-to-one>
//表明多个学生可以对应一条状态，name对应Student类中的属性status，id为student_status表中的id字段（即student表中有一个外键student_status_id,对应student_status表的id字段，class表示一的一方为StudentStatus类）
<many-to-one name="status" column="id" class="com.ffy.studentmanage.StudentStatus"></many-to-one>
</class>

一方代码

1.在StudentStatus类（一的那方）中加入一个对方（多方）类型的属性，即学生信息类的实例。

public class StudentStatus {
private int id;
private String code;
private String name;
private String description;

//加入一个集合，泛型为Student，用于存放该状态对应的学生，因为一条状态对呀多个学生，所以需要用集合表示
private Set<Student> students=new HashSet<>();

public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}

public Set<Student> getStudents() {
return students;
}
public void setStudents(Set<Student> students) {
this.students = students;
}
public String toString(){
return "id:"+this.id+";name"+this.name+";code:"+this.code;
}
}

2.配置studentStatus.hbm.xml,基本属性配置方法不变，Students的配置如下。

<hibernate-mapping>
<class name="com.ffy.studentmanage.StudentStatus" table="student_status">
<id name="id" column="id">
<generator class="assigned"></generator>
</id>
<property name="code" column="code"></property>
<property name="name" column="name"></property>
<property name="description" column="description"></property>
//集合存放该状态对应的多个学生，name为属性名（即集合名称）,column表示相关联的外键，
<set name="students" cascade="all" inverse="true">
<key column="student_status_id"></key>
//表示一个状态对应多个学生，calss表示对应的多的那方的类（即与之相对应的类）
<one-to-many class="com.ffy.studentmanage.Student"/>
</set>
</class>
</hibernate-mapping>

二、annotation注解映射

多的那方

1.在hibernate.cfg.xml注册Student类

<mapping class="com.ffy.studentmanage.Student"/>

2.在Student类中添加注解

@Entity
@Table(name="student")
public class Student {
@Id
@Column(name="id")
private int id;
@Column(name="sid")
private int sid;
@Column(name="firstname")
private String firstName;
@Column(name="lastname")
private String lastName;
@Column(name="gender")
private String gender;
@Column(name="phone")
private String phone;
@Column(name="email")
private String email;
@Column(name="date_of_birth")
private String dateOfBirth;
@Column(name="height")
private double height=160;

/*
*  多的一方，加入对方的一个类的属性。一个学生对于一个状态。
*  name="student_status_id"表明一的那方为外键student_status_id锁对应的表
*/
@ManyToOne
@JoinColumn(name="student_status_id")
private StudentStatus status;

@OneToOne
@PrimaryKeyJoinColumn
private StudentLogin studentLogin;

public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public int getSid() {
return sid;
}
public void setSid(int sid) {
this.sid = sid;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastname() {
return lastName;
}
public void setLastname(String lastName) {
this.lastName = lastName;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getDateOfBirth() {
return dateOfBirth;
}
public void setDateOfBirth(String dateOfBirth) {
this.dateOfBirth = dateOfBirth;
}
public double getHeight() {
return height;
}
public void setHeight(double height) {
this.height = height;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}

public StudentStatus getStatus() {
return status;
}
public void setStatus(StudentStatus status) {
this.status = status;
}
public StudentLogin getStudentLogin() {
return studentLogin;
}
public void setStudentLogin(StudentLogin studentLogin) {
this.studentLogin = studentLogin;
}
public String toString(){
return this.id+":"+this.lastName+this.firstName+this.gender+":"+this.phone+":"+this.email+";username"+studentLogin.getUsername()+";password:"+studentLogin.getPassword();
}
}

一的那方#

1.在hibernate.cfg.xml注册StudentStatus类

<mapping class="com.ffy.studentmanage.StudentStatus"/>

2.在StudentStatus类中添加注解

package com.ffy.studentmanage;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;
import javax.persistence.Table;

@Table(name="student_status")
@Entity
public class StudentStatus {
@Id()
@Column(name="id")
private int id;
@Column(name="code")
private String code;
@Column(name="name")
private String name;
@Column(name="description")
private String description;

/*
* 加入一个集合，泛型为Student，用于存放该状态对应的学生，因为一条状态对呀多个学生，所以需要用集合表示
* name="id"：student_status表的主键为Student表的外键，这样子就能找到Student(多的那方)
* 的student_status_id为student_status表的id的字段，两者对应
*/
@OneToMany
@JoinColumn(name="id")
private Set<Student> students=new HashSet<>();

public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}

public Set<Student> getStudents() {
return students;
}
public void setStudents(Set<Student> students) {
this.students = students;
}
public String toString(){
return "id:"+this.id+";name"+this.name+";code:"+this.code;
}
}