hibernate之cascade(一)

TrainingStudent.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>
    <class name="com.hibernate.entity.TrainingStudent" table="training_student" schema="dbo" catalog="pubs">
        <id name="id" type="java.lang.Integer">
            <column name="id" />
            <generator class="identity" />
        </id>
        <property name="classId" type="java.lang.Integer" insert="false" update="false">
            <column name="class_id" />
        </property>
        <property name="stuName" type="java.lang.String">
            <column name="stu_name" length="50" />
        </property>
        <many-to-one name="trainingClass" class="com.hibernate.entity.TrainingClass" fetch="select" cascade="all" lazy="false" >
	        <column name="class_id" not-null="true"></column>
        </many-to-one>
    </class>
</hibernate-mapping>

 

TrainingClass.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>
    <class name="com.hibernate.entity.TrainingClass" table="training_class" schema="dbo" catalog="pubs">
        <id name="id" type="java.lang.Integer">
            <column name="id" />
            <generator class="identity" />
        </id>
        <property name="className" type="java.lang.String">
            <column name="class_name" length="50" />
        </property>
        <set name="trainingStudent" cascade="all">
        	<key column="class_id" not-null="false"></key>
        	<one-to-many class="com.hibernate.entity.TrainingStudent" />
        </set>
    </class>
</hibernate-mapping> 

 

 

package com.hibernate.entity;

import java.util.HashSet;
import java.util.Set;
public class TrainingClass implements java.io.Serializable {

	// Fields

	private Integer id;
	private String className;
	private Set<TrainingStudent> trainingStudent = new HashSet();

	// Constructors

	/** default constructor */
	public TrainingClass() {
	}

	// Property accessors

	public Integer getId() {
		return this.id;
	}

	public void setId(Integer id) {
		this.id = id;
	}

	public String getClassName() {
		return this.className;
	}

	public void setClassName(String className) {
		this.className = className;
	}

	public Set<TrainingStudent> getTrainingStudent() {
		return trainingStudent;
	}

	public void setTrainingStudent(Set<TrainingStudent> trainingStudent) {
		this.trainingStudent = trainingStudent;
	}

}

 

 

 

package com.hibernate.entity;

public class TrainingStudent implements java.io.Serializable {

	// Fields

	private Integer id;
	private Integer classId;
	private String stuName;
	private TrainingClass trainingClass;

	// Constructors

	/** default constructor */
	public TrainingStudent() {
	}

	// Property accessors

	public Integer getId() {
		return this.id;
	}

	public void setId(Integer id) {
		this.id = id;
	}

	public Integer getClassId() {
		return this.classId;
	}

	public void setClassId(Integer classId) {
		this.classId = classId;
	}

	public String getStuName() {
		return this.stuName;
	}

	public void setStuName(String stuName) {
		this.stuName = stuName;
	}

	public TrainingClass getTrainingClass() {
		return trainingClass;
	}

	public void setTrainingClass(TrainingClass trainingClass) {
		this.trainingClass = trainingClass;
	}

}

 

 以上是例子需要的内容。

one端可以级联修改many端的数据，many端可以级联删除one端。many端可以修改自己数据，但是不能通过many端去修改one端的数据。比如:

 

Session session=HibernateSessionFactory.getSession();

session.beginTransaction();

TrainingStudent ts=(TrainingStudent) session.get(TrainingStudent.class, 6);

ts.setClassId(4);

 

 

ts.setClassId(4);

TrainingClass t1=(TrainingClass) session.get(TrainingClass.class,4);

ts.setTrainingClass(t1);

session.saveOrUpdate(ts);

这样做是允许的，因为它是在修改自身的数据。但是下面这样是不允许的:

ts.getTrainingClass().setId();

因为这是在通过many端去修改one端内部的主键。这样做是不允许的。