Hibernate 一对一联系关系

Hibernate 一对一关联

Student(学生)和Document(学籍)存在一对一关系

 

Student.java

 

/**
 * 
 */
package com.hb.jo;

/**
 * @author dudong0726
 *
 * @date 2011-11-8 下午04:36:25
 *
 */
public class Student {

	private long id;
	private String name;
	private String email;
	private Document doc;
	
	public long getId() {
		return id;
	}
	public void setId(long id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getEmail() {
		return email;
	}
	public void setEmail(String email) {
		this.email = email;
	}
	public Document getDoc() {
		return doc;
	}
	public void setDoc(Document doc) {
		this.doc = doc;
	}
	
}

 

Document.java

 

/**
 * 
 */
package com.hb.jo;

/**
 * @author dudong0726
 *
 * @date 2011-11-8 下午04:37:19
 *
 */
public class Document {

	private long id;
	private String number; 
	private Student stu;
	
	public long getId() {
		return id;
	}
	public void setId(long id) {
		this.id = id;
	}
	public String getNumber() {
		return number;
	}
	public void setNumber(String number) {
		this.number = number;
	}
	public Student getStu() {
		return stu;
	}
	public void setStu(Student stu) {
		this.stu = stu;
	}
	
	
}

 

student.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>
	<class name="com.hb.jo.Student" table="student">
		<id name="id" column="stu_id">
			<generator class="foreign">
				<param name="property">doc</param>
			</generator>
		</id>
		<property name="name"></property>
		<property name="email"></property>
		<one-to-one name="doc" class="com.hb.jo.Document" constrained="true"></one-to-one>
	</class>
</hibernate-mapping>

 

document.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>
	<class name="com.hb.jo.Document" table="document">
		<id name="id" column="doc_id">
			<generator class="native"></generator>
		</id>
		<property name="number"></property>
		<one-to-one name="stu" class="com.hb.jo.Student"></one-to-one>
	</class>
</hibernate-mapping>

 

 

需要注意的地方：

 

1、为保证两个关联的表中id的一致，需要在其中一个表中的id作为外键，其生成策略使用和他关联表的id；

 

2、需要在有外键的表中指定 constrained = 'true',来明确指定通过外键对主键进行关联；此字段影响save和delete的先后顺序，因为其id生成需要与其关联表的主键，所以每次save先save关联的表，在查询关联表的id作为id；在删除时和save相反。