Hibernate 多对一（MaryToOne）

例子：学生与老师的多对一

学生实体类

package entity;

/**
 * Student 实体类
 * */
public class Student {
	private int id;//编号
	private String name;//姓名
	private Teacher teacher;//用来作主外键约束的
	
	/*
	 * 构造方法
	 * */
	public Student() {
	}
	public Student(String name) {
		this.name = name;
	}
	
	/*
	 * 封装方法
	 * */
	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 Teacher getTeacher() {
		return teacher;
	}
	public void setTeacher(Teacher teacher) {
		this.teacher = teacher;
	}
}

 

学生实体类的XML配置

<?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="entity.Student">
		<id name="id">
			<generator class="sequence">
				<param name="sequence">seq_student</param>
			</generator>
		</id>
		<property name="name"></property>
		<many-to-one name="teacher" column="teacherid" class="entity.Teacher"></many-to-one>
	</class>
</hibernate-mapping>

 

老师实体类

package entity;

/**
 * Teacher 实体类
 * */
public class Teacher {
	private int id;//编号
	private String name;//姓名
	
	/*
	 * 构造方法
	 * */
	public Teacher() {
	}
	public Teacher(String name) {
		this.name = name;
	}
	
	/*
	 * 封装方法
	 * */
	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;
	}
}

 

老师实体类的XML配置

<?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="entity.Teacher">
		<id name="id">
			<generator class="sequence">
				<param name="sequence">seq_teacher</param>
			</generator>
		</id>
		<property name="name"></property>
	</class>
</hibernate-mapping>

 

使用hibernate.cfg.xml映射其的XML路径

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

<hibernate-configuration>
<session-factory>
	<!-- 数据库URL -->
	<property name="connection.url">
		jdbc:oracle:thin:@localhost:1521:oracle11
	</property>
	<!-- 数据库用户 -->
	<property name="connection.username">A_hr</property>
	<!-- 数据库用户密码 -->
	<property name="connection.password">123456</property>
	<!-- 数据库 JDBC 驱动 -->
	<property name="connection.driver_class">
		oracle.jdbc.driver.OracleDriver
	</property>
	<!-- 是否将运行期生成的 SQL 输出到日志以供调试 -->
	<property name="show_sql">true</property>
	<!-- 每个数据库都有其对应的 Dialect 以匹配其平台特征 -->
	<property name="dialect">
		org.hibernate.dialect.Oracle10gDialect
	</property>
	<property name="hbm2ddl.auto">create</property>
	<mapping resource="entity/Student.hbm.xml" />
	<mapping resource="entity/Teacher.hbm.xml" />
</session-factory>
</hibernate-configuration>

 

进行数据的操作

package test;

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.Transaction;

import entity.Student;
import entity.Teacher;

import util.HibernateSessionFactory;

public class MaryToOneTest {
	public static void main(String[] args) {
		maryToOne();
	}
	private static void maryToOne() {
		Session session = HibernateSessionFactory.getSession();
		Transaction tx = null;
		Teacher teacher = new Teacher("李炎恢");
		Student student1 = new Student("吴者然");
		Student student2 = new Student("何开");
		try {
			student1.setTeacher(teacher);
			student2.setTeacher(teacher);
			tx = session.beginTransaction();
			session.save(teacher);
			session.save(student1);
			session.save(student2);
			tx.commit();
			System.out.println("保存成功!!!");
		} catch (HibernateException e) {
			e.printStackTrace();
			tx.rollback();
		}finally{
			HibernateSessionFactory.closeSession();
		}
	}
	
}

 

效果图：

 

在数据库查询这两条语句

select id, name, teacherid from student;
select id, name from teacher