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")@Entitypublic 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;    }}