Hibernet OneToMany ManyToOne

最新推荐文章于 2026-01-04 20:05:27 发布

原创最新推荐文章于 2026-01-04 20:05:27 发布 · 686 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#class #string #table #session #dao #mysql

本文通过实例演示了Hibernate框架中ManyToOne和OneToMany关联映射的具体配置方法，并提供了完整的XML配置文件和Java类代码示例。

ManyToOne

hibernet.cfg.xml

<!DOCTYPE hibernate-configuration PUBLIC
	"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
	"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
	<session-factory>
	  <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
	  <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
	  <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/test</property>
	  <property name="hibernate.connection.username">root</property>
	  <property name="hibernate.connection.password">root</property>
	  
	  <property name="show_sql">true</property>
	  <property name="hibernate.hbm2ddl.auto">update</property>
	  
	  <mapping resource="po/Employee.hbm.xml"></mapping>
	  <mapping resource="po/Department.hbm.xml"></mapping>
	</session-factory>
</hibernate-configuration>

Employee

package po;

public class Employee {
	private int employeeId;
	private String ename;
	private Department department;

	//省略get、set和无参构造

}

Employee.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
	"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
	"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="po">

	<class name="Employee" table="t_employee">
		<id name="employeeId" column="id">
			<generator class="native"></generator>
		</id>
		<property name="ename" column="ename"></property>
		<many-to-one name="department" class="Department" cascade="all">
		  <column name="deptId"></column>
		</many-to-one><!--传说中的外键。-->

	</class>

</hibernate-mapping>

Department

package po;

public class Department {
	private int deptId;
	private String dname;
	private String location;

	//省略get、set和无参构造

}

Department.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
	"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
	"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="po">

	<class name="Department" table="t_department">
		<id name="deptId" column="id">
			<generator class="native"></generator>
		</id>
		<property name="dname" column="dname"></property>
		<property name="location" column="location" length="40"></property>
	</class>

</hibernate-mapping>

EmployeeDao 在这个类中做测试。

package dao;

import org.hibernate.Session;

import po.Department;
import po.Employee;
import util.HibUtil;

public class EmployeeDao {
	public void add(Employee employee){
		Session session = HibUtil.getSession();
		session.beginTransaction();
		session.save(employee);
		session.getTransaction().commit();
		session.close();
	}
	public static void main(String[] args) {
		EmployeeDao dao = new EmployeeDao();
		Employee employee = new Employee();
		employee.setEname("wang");
		Department department = new Department();
		department.setDname("项目部");
		department.setLocation("三楼");
		employee.setDepartment(department);
		dao.add(employee);
	}
}

OneToMany只修改department.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
	"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
	"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="po">

	<class name="Department" table="t_department">
		<id name="deptId" column="id">
			<generator class="native"></generator>
		</id>
		<property name="dname" column="dname"></property>
		<property name="location" column="location"></property>
		<set name="employees" cascade="all">
		  <key>
		    <column name="deptId"></column>
		  </key>
		  <one-to-many class="Employee"/>
		</set>
	</class>

</hibernate-mapping>

经试验发现有了one-to-mang之后，mang-to-one就没用了。基本得出结论啊：无论是one-to-mang还是mang-to-one的使用都是双向的任何一个的使用都可以建立起来双向的连接。