Hibernate one-to-one一对一映射

xiaoxiao2021-03-25 64

hibernate 关系映射 one-to-one主要有三种实现方式 1.通过外键方式实现以学生和电脑为例(Student-Computer) 建表sql语句： Java代码 CREATE DATABASE `onetoone` CHARACTER SET 'utf8'; USE `onetoone`; DROP TABLE IF EXISTS `student`; CREATE TABLE `student` ( `id` int(11) NOT NULL auto_increment, `name` varchar(255) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; DROP TABLE IF EXISTS `computer`; CREATE TABLE `computer` ( `id` int(11) NOT NULL auto_increment, `name` varchar(255) NOT NULL, `student_id` int(11) , foreign key (`student_id`) references student(`id`), PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; [java] view plain copy CREATE DATABASE `onetoone` CHARACTER SET 'utf8'; USE `onetoone`; DROP TABLE IF EXISTS `student`; CREATE TABLE `student` ( `id` int(11) NOT NULL auto_increment, `name` varchar(255) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; DROP TABLE IF EXISTS `computer`; CREATE TABLE `computer` ( `id` int(11) NOT NULL auto_increment, `name` varchar(255) NOT NULL, `student_id` int(11) , foreign key (`student_id`) references student(`id`), PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; Student.java: Java代码 package com.domain; public class Student implements java.io.Serializable { private Integer id; private String name; private Computer computer; public Student() { } public Student(String name) { this.name = name; } public Integer getId() { return this.id; } public void setId(Integer id) { this.id = id; } public String getName() { return this.name; } public void setName(String name) { this.name = name; } public Computer getComputer() { return computer; } public void setComputer(Computer computer) { this.computer = computer; } } [java] view plain copy package com.domain; public class Student implements java.io.Serializable { private Integer id; private String name; private Computer computer; public Student() { } public Student(String name) { this.name = name; } public Integer getId() { return this.id; } public void setId(Integer id) { this.id = id; } public String getName() { return this.name; } public void setName(String name) { this.name = name; } public Computer getComputer() { return computer; } public void setComputer(Computer computer) { this.computer = computer; } } Computer.java: Java代码 package com.domain; public class Computer implements java.io.Serializable { private Integer id; private Student student; private String name; public Computer() { } public Computer(String name) { this.name = name; } public Computer(Student student, String name) { this.student = student; this.name = name; } public Integer getId() { return this.id; } public void setId(Integer id) { this.id = id; } public Student getStudent() { return this.student; } public void setStudent(Student student) { this.student = student; } public String getName() { return this.name; } public void setName(String name) { this.name = name; } } [java] view plain copy package com.domain; public class Computer implements java.io.Serializable { private Integer id; private Student student; private String name; public Computer() { } public Computer(String name) { this.name = name; } public Computer(Student student, String name) { this.student = student; this.name = name; } public Integer getId() { return this.id; } public void setId(Integer id) { this.id = id; } public Student getStudent() { return this.student; } public void setStudent(Student student) { this.student = student; } public String getName() { return this.name; } public void setName(String name) { this.name = name; } } Student.hbm.xml: Java代码 <?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.domain.Student" table="student" catalog="onetoone"> <id name="id" type="java.lang.Integer"> <column name="id" /> <generator class="native" /> </id> <property name="name" type="java.lang.String"> <column name="name" not-null="true" /> </property>  <one-to-one cascade="delete,save-update" name="computer" class="com.domain.Computer" property-ref="student"></one-to-one> </class> </hibernate-mapping> [java] view plain copy <?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.domain.Student" table="student" catalog="onetoone"> <id name="id" type="java.lang.Integer"> <column name="id" /> <generator class="native" /> </id> <property name="name" type="java.lang.String"> <column name="name" not-null="true" /> </property>  <one-to-one cascade="delete,save-update" name="computer" class="com.domain.Computer" property-ref="student"></one-to-one> </class> </hibernate-mapping> Computer.hbm.xml: Java代码 <?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.domain.Computer" table="computer" catalog="onetoone"> <id name="id" type="java.lang.Integer"> <column name="id" /> <generator class="native" /> </id> <property name="name" type="java.lang.String"> <column name="name" not-null="true" /> </property>  <many-to-one name="student" class="com.domain.Student" unique="true"> <column name="student_id" /> </many-to-one> </class> </hibernate-mapping> [java] view plain copy <?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.domain.Computer" table="computer" catalog="onetoone"> <id name="id" type="java.lang.Integer"> <column name="id" /> <generator class="native" /> </id> <property name="name" type="java.lang.String"> <column name="name" not-null="true" /> </property>  <many-to-one name="student" class="com.domain.Student" unique="true"> <column name="student_id" /> </many-to-one> </class> </hibernate-mapping> 测试类： Java代码 package com.domain; import org.hibernate.Query; import org.hibernate.Session; import com.util.HibernateSessionFactory; public class Test { public static void main(String[] args){ Session session = HibernateSessionFactory.getSession(); //save Student student = new Student(); student.setName("student9"); Computer computer = new Computer(); computer.setName("Intel 9"); //computer.setStudent(student)和student.setComputer(computer);都必须要 computer.setStudent(student); student.setComputer(computer); session.save(student); /** 执行的sql: Hibernate: insert into onetoone.student (name) values (?) Hibernate: insert into onetoone.computer (name, student_id) values (?, ?) */ // session.beginTransaction().commit(); //query // String hql = "from Student where name=?"; // Query query = session.createQuery(hql); // query.setString(0, "student3"); // // Student student = (Student)query.uniqueResult(); // System.out.println(student.getId() + " : " + student.getComputer().getName()); //delete // Student student = (Student)session.load(Student.class, new Integer(1)); // session.delete(student); // session.beginTransaction().commit(); /** 执行的sql为： Hibernate: select student0_.id as id0_1_, student0_.name as name0_1_, computer1_.id as id1_0_, computer1_.name as name1_0_, computer1_.student_id as student3_1_0_ from onetoone.student student0_ left outer join onetoone.computer computer1_ on student0_.id=computer1_.student_id where student0_.id=? Hibernate: delete from onetoone.computer where id=? Hibernate: delete from onetoone.student where id=? */ session.close(); } } [java] view plain copy package com.domain; import org.hibernate.Query; import org.hibernate.Session; import com.util.HibernateSessionFactory; public class Test { public static void main(String[] args){ Session session = HibernateSessionFactory.getSession(); //save Student student = new Student(); student.setName("student9"); Computer computer = new Computer(); computer.setName("Intel 9"); //computer.setStudent(student)和student.setComputer(computer);都必须要 computer.setStudent(student); student.setComputer(computer); session.save(student); /** 执行的sql: Hibernate: insert into onetoone.student (name) values (?) Hibernate: insert into onetoone.computer (name, student_id) values (?, ?) */ // session.beginTransaction().commit(); //query // String hql = "from Student where name=?"; // Query query = session.createQuery(hql); // query.setString(0, "student3"); // // Student student = (Student)query.uniqueResult(); // System.out.println(student.getId() + " : " + student.getComputer().getName()); //delete // Student student = (Student)session.load(Student.class, new Integer(1)); // session.delete(student); // session.beginTransaction().commit(); /** 执行的sql为： Hibernate: select student0_.id as id0_1_, student0_.name as name0_1_, computer1_.id as id1_0_, computer1_.name as name1_0_, computer1_.student_id as student3_1_0_ from onetoone.student student0_ left outer join onetoone.computer computer1_ on student0_.id=computer1_.student_id where student0_.id=? Hibernate: delete from onetoone.computer where id=? Hibernate: delete from onetoone.student where id=? */ session.close(); } } 2.通过主键方式实现(一个表的主键由另一个表的主键决定)，在这里Computer的主键由Student的主键决定。 Student.hbm.xml: Java代码 <?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.domain.Student" table="student" catalog="onetoone"> <id name="id" type="java.lang.Integer"> <column name="id" /> <generator class="native" /> </id> <property name="name" type="java.lang.String"> <column name="name" not-null="true" /> </property>  <one-to-one name="computer"/> </class> </hibernate-mapping> [java] view plain copy <?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.domain.Student" table="student" catalog="onetoone"> <id name="id" type="java.lang.Integer"> <column name="id" /> <generator class="native" /> </id> <property name="name" type="java.lang.String"> <column name="name" not-null="true" /> </property>  <one-to-one name="computer"/> </class> </hibernate-mapping> Comuter.hbm.xml: Java代码 <?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.domain.Computer" table="computer" catalog="onetoone"> <id name="id" type="java.lang.Integer"> <column name="id" />   <generator class="foreign"> <param name="property">student</param> </generator> </id> <property name="name" type="java.lang.String"> <column name="name" not-null="true" /> </property>  <one-to-one name="student"/> </class> </hibernate-mapping> [java] view plain copy <?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.domain.Computer" table="computer" catalog="onetoone"> <id name="id" type="java.lang.Integer"> <column name="id" />   <generator class="foreign"> <param name="property">student</param> </generator> </id> <property name="name" type="java.lang.String"> <column name="name" not-null="true" /> </property>  <one-to-one name="student"/> </class> </hibernate-mapping> TestMainKey.java: Java代码 package com.domain; import org.hibernate.Session; import com.util.HibernateSessionFactory; public class TestMainKey { public static void main(String[] args){ Session session = HibernateSessionFactory.getSession(); //save Student student = new Student(); student.setName("student15"); Computer computer = new Computer(); computer.setName("Intel 15"); computer.setStudent(student); // student.setComputer(computer); //因为save 2个表，所以不需要双向赋值 session.save(student); session.save(computer); session.beginTransaction().commit(); session.close(); } } [java] view plain copy package com.domain; import org.hibernate.Session; import com.util.HibernateSessionFactory; public class TestMainKey { public static void main(String[] args){ Session session = HibernateSessionFactory.getSession(); //save Student student = new Student(); student.setName("student15"); Computer computer = new Computer(); computer.setName("Intel 15"); computer.setStudent(student); // student.setComputer(computer); //因为save 2个表，所以不需要双向赋值 session.save(student); session.save(computer); session.beginTransaction().commit(); session.close(); } } 3.通过关系表实现： Java代码 DROP TABLE IF EXISTS `st`; create table stu_com( stu_id int not null, com_id int not null )ENGINE=InnoDB DEFAULT CHARSET=utf8; [java] view plain copy DROP TABLE IF EXISTS `st`; create table stu_com( stu_id int not null, com_id int not null )ENGINE=InnoDB DEFAULT CHARSET=utf8; Java代码  <join table="stu-com" optional="true" inverse="true"> <key column="com_id"/> <many-to-one name="student" column="stu_id" unique="true"/> </join> [java] view plain copy  <join table="stu-com" optional="true" inverse="true"> <key column="com_id"/> <many-to-one name="student" column="stu_id" unique="true"/> </join>

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