Hibernate双向一对一关系

关系模型:
首先建两个表，一个是病人表(patient)，一个是病历表(note).一个病人对应一张病历表

patient表:

note表:

其中patinetID是外键，对应patient表的id;

建表语句如下:

patient:

CREATE TABLE `patient`
(
`id` bigint(20) NOT NULL auto_increment,

`name` varchar(20) NOT NULL,

`address` varchar(100) default NULL,

PRIMARY KEY (`id`)
)
ENGINE=InnoDB DEFAULT CHARSET=utf8;

note:

CREATE TABLE `note`
(
`id` bigint(20) NOT NULL auto_increment,

`content` varchar(1000) character set utf8 collate utf8_unicode_ci default NULL,

`patientID` bigint(20) NOT NULL,
PRIMARY KEY (`id`),

KEY `patientID` (`patientID`),

CONSTRAINT `note_ibfk_2` FOREIGN KEY (`patientID`) REFERENCES `patient` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
)
ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='InnoDB free: 3072 kB;
(`patientID`) REFER `book/patient`(`id';

 

对象模型：

Patient.java:

public class Patient {
    private long id;
    private String name;
    private String address;
    private Note myCase;
　　//省略get,set方法

Note.java:

public class Note {
    private long id;
    private String content;
    private Patient patientId;
　　//省略get,set方法

关系对象映射关系：

Patient.hbm.xml:

<hibernate-mapping>
    <class name="com.sunflower.pojo.Patient" table="patient">
        <id name="id" type="long">
            <column name="id"></column>
            <generator class="identity"></generator>
        </id>
        
        <property name="name" type="string">
            <column name="name" not-null="true"></column>
        </property>
        
        <property name="address" type="string">
            <column name="address"></column>
        </property>
        
        <one-to-one name="myCase" class="com.sunflower.pojo.Note" cascade="all">
        </one-to-one>
    </class>
</hibernate-mapping>

注意第16行采用<one-to-one>对应关系，cascade="all"表示级联的模式为所有，保存，删除和修改

Note.hbm.xml:

<hibernate-mapping>
    <class name="com.sunflower.pojo.Note" table="note">
        <id name="id" type="long"> 
            <column name="id"></column>
            <generator class="identity"></generator>
        </id>
        
        <property name="content" type="string">
            <column name="content"></column>
        </property>
        
        <many-to-one name="patientId" class="com.sunflower.pojo.Patient" unique="true" fetch="join">
            <column name="patientID" />
        </many-to-one>
    </class>
</hibernate-mapping>

这里注意第12行，采用的是<many-to-one>模式，但是unique="true"表示了一对一的模式，这里说明一对一其实是多对一的特例。作者个人觉得，在关系模式中作为外键的属性在映射中都采用<many-to-one>模式.

Hibernate配置文件(hibernate.cfg.xml):

<hibernate-configuration>

    <session-factory>
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
        <property name="connection.url">jdbc:mysql://localhost:3306/book</property>
        <property name="connection.username">yuan</property>
        <property name="connection.password">hanyuan9113</property>
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="myeclipse.connection.profile">mysqldriver</property>
        <property name="show_sql">true</property>
        <property name="current_session_context_class">thread</property>
        
        <mapping resource="com/sunflower/pojo/Note.hbm.xml"/>
        <mapping resource="com/sunflower/pojo/Patient.hbm.xml"/>
    </session-factory>

</hibernate-configuration>

测试：

Test.java:

public class Test {

    private void save() {
        Note case1 = new Note();
        case1.setContent("hello");

        Patient patient1 = new Patient();
        patient1.setName("邓先流");
        patient1.setAddress("北京路23号");
        patient1.setMyCase(case1);

        case1.setPatientId(patient1);

        Session session = HibernateUtil.openSession();
        Transaction ts = session.beginTransaction();

        try {
            session.delete(patient1);
            ts.commit();
        }
        catch (Exception e) {
            e.printStackTrace();
            ts.rollback();
        }
        finally {
            HibernateUtil.clossFactory();
        }
    }

    private void delete() {
        Session session = HibernateUtil.openSession();
        Transaction ts = session.beginTransaction();

        try {
            Patient patient = (Patient) session.get(Patient.class, new Long(11));
            session.delete(patient);
            ts.commit();
        }
        catch (Exception e) {
            e.printStackTrace();
            ts.rollback();
        }
        finally {
            HibernateUtil.clossFactory();
        }
    }

    public static void main(String[] args) {
        Test test = new Test();
        test.delete();
    }
}

这个项目遇到的问题需要注意：

本来对象模型中的Note为Case,在插入的时候出现了sql语法错误提示，应该是case是作为关键字，影响到sql语句，后来将表名和对象名改为Note之后问题就解决了。

 

项目源码地址:http://115.com/file/benvyvql#onetoone.rar