Hibernate多对一双向关联(xml配置)-优快云博客

本文介绍使用Hibernate实现多对一关系映射的方法，包括Department和Employee两个类的定义，以及对应的Hibernate映射文件Department.hbm.xml和Employee.hbm.xml。通过示例代码展示了如何插入和查询带有部门信息的员工数据。

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Department.java

package com.many2one.bean;

import java.util.Set;

public class Department {

    private int id;
    private String name;
    private Set<Employee> sets;
    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<Employee> getSets() {
        return sets;
    }
    public void setSets(Set<Employee> sets) {
        this.sets = sets;
    }

}

Employee.java

package com.many2one.bean;

public class Employee {

    private int id;
    private String name;
    private Department department;
    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 Department getDepartment() {
        return department;
    }
    public void setDepartment(Department department) {
        this.department = department;
    }


}

映射文件
Department.hbm.xml

<?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 package="com.many2one.bean">
        <class name="Department" table="department" catalog="Hibernate_Many2One">
            <id name="id" column="id">
                <generator class="native"/>
            </id>
            <property name="name" column="name"/>

        </class>
    </hibernate-mapping>

Employee.hbm.xml

<?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 package="com.many2one.bean">
        <class name="Employee" table="employee" catalog="Hibernate_Many2One">
            <id name="id" column="id">
                <generator class="native"/>
            </id>
            <property name="name" column="name"/>
            <many-to-one name="department" column="deptid" cascade="all" />
        </class>
    </hibernate-mapping>

导出的sql

create table Hibernate_Many2One.department (
        id integer not null auto_increment,
        name varchar(255),
        primary key (id)
    )

    create table Hibernate_Many2One.employee (
        id integer not null auto_increment,
        name varchar(255),
        deptid integer,
        primary key (id)
    )

    alter table Hibernate_Many2One.employee
        add index FK4722E6AE3829E242 (deptid),
        add constraint FK4722E6AE3829E242
        foreign key (deptid)
        references Hibernate_Many2One.department (id)

测试代码

@Test
    public void insert(){
        Session session=HibernateSessionFactory.getSession();
        Transaction transaction=session.beginTransaction();
        try {
            transaction.begin();
            Department department=new Department();
            department.setName("软件测试部");
            Employee employee=new Employee();
            employee.setName("张三");
            employee.setDepartment(department);
            session.save(employee);
            transaction.commit();
        } catch (HibernateException e) {
            e.printStackTrace();
        }
    }


    @Test
    public void select(){
        Session session=HibernateSessionFactory.getSession();
        try {
            Employee employee=(Employee) session.get(Employee.class, 1);
            System.out.println(employee.getName());
            System.out.println(employee.getDepartment().getName());
        } catch (HibernateException e) {
            e.printStackTrace();
        }
    }