Hibernet OneToMany ManyToOne

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。