Hibernate的继承关系是什么

这篇文章主要讲解了“Hibernate的继承关系是什么”，文中的讲解内容简单清晰，易于学习与理解，下面请大家跟着小编的思路慢慢深入，一起来研究和学习“Hibernate的继承关系是什么”吧！

Hibernate的继承关系分为三种：一张表对应一整棵类继承树、一个类对应一张表、每一个具体类对应一张表。

三个java类Person、Student、Teacher，Student和Teacher继承Person类并且Student和Teacher没有任何关系

代码如下：

Person.java

package com.zzn.hibernate.model;   public class Person {      private int id;      private String name;      private int age;      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 int getAge() {          return age;      }      public void setAge(int age) {          this.age = age;      }              }

Student.java

package com.zzn.hibernate.model;   public class Student extends Person {      private String cardId;       public String getCardId() {          return cardId;      }      public void setCardId(String cardId) {          this.cardId = cardId;      }  }

Teacher.java

package com.zzn.hibernate.model;   public class Teacher extends Person {      private int salary;      public int getSalary() {          return salary;      }      public void setSalary(int salary) {          this.salary = salary;      }  }

Hibernate的继承关系表：一张表对应一整棵类继承树时

Person.hbm.xml

< ?xml version="1.0" encoding='gb2312'?>    < !DOCTYPE hibernate-mapping PUBLIC            "-//Hibernate/Hibernate Mapping DTD 3.0//EN"            "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">           < hibernate-mapping package="com.zzn.hibernate.model">      < class name="Person" table="person">         < id name="id" column="id">             < generator class="identity" />         < /id>         < discriminator column="personType" type="java.lang.String" />   < !-- 指定描述符对应的列明，注意discrimination标签只能紧跟在id标签后面 -->                   < property name="name" type="java.lang.String" />                < !-- 公用的name属性，被两个sbuclass标签所用 -->         < property name="age" type="java.lang.Integer" />                < !-- 公用的age属性，被两个sbuclass标签所用 -->                   < subclass name="Student" discriminator-value="student">            < !-- 映射子类Student，描述符是student，此时已经映射Student类，所以不必再写Student.hbm.xml -->             < property name="cardId" type="java.lang.String" />            < !-- Student私有的属性 -->         < /subclass>         < subclass name="Teacher" discriminator-value="teacher" >             < property name="salary" type="java.lang.Integer" />            < !-- Teacher私有的属性 -->         < /subclass>                   < /class>       < /hibernate-mapping>

一个类对应一张表

< ?xml version="1.0" encoding='gb2312'?>    < !DOCTYPE hibernate-mapping PUBLIC            "-//Hibernate/Hibernate Mapping DTD 3.0//EN"            "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">           < hibernate-mapping package="com.zzn.hibernate.model">      < class name="Person" table="person">         < id name="id" column="id">             < generator class="identity" />         < /id>         < property name="name" type="java.lang.String" />                          < property name="age" type="java.lang.Integer" />         < joined-subclass name="Student" table="student">             < key column="id" />             < property name="cardId" type="java.lang.String" />         < /joined-subclass>                   < joined-subclass name="Teacher" table="teacher">             < key column="id"/>             < property name="salary" type="java.lang.Integer" />         < /joined-subclass>     < /class>       < /hibernate-mapping>

hibernate.hbm.xml

< ?xml version='1.0' encoding='UTF-8'?> < !DOCTYPE hibernate-configuration PUBLIC            "-//Hibernate/Hibernate Configuration DTD 3.0//EN"            "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> < hibernate-configuration>     < session-factory>         < property name="show_sql">true< /property>         < property name="hibernate.hbm2ddl.auto">update< /property>         < property name="connection.username">sa< /property>         < property name="connection.password">< /property>         < property name="connection.url">jdbc:jtds:sqlserver://localhost:1433;databasename=hibernate_test< /property>         < property name="dialect">org.hibernate.dialect.SQLServerDialect< /property>         < property name="myeclipse.connection.profile">SQL2005< /property>         < property name="connection.driver_class">net.sourceforge.jtds.jdbc.Driver< /property>         < mapping resource="com/zzn/hibernate/model/Person.hbm.xml"/>     < /session-factory> < /hibernate-configuration>

Hibernate的继承关系测试文件SubclassTest.java

package com.zzn.hibernate.test;   import java.util.Iterator;   import org.hibernate.Query;  import org.hibernate.Session;  import org.hibernate.SessionFactory;  import org.hibernate.Transaction;  import org.hibernate.cfg.Configuration;   import com.zzn.hibernate.model.Person;  import com.zzn.hibernate.model.Student;  import com.zzn.hibernate.model.Teacher;   public class SubClassTest {      public static void main(String[] args) {          add();          select();      }       public static void add() {          Configuration configuration = null;          SessionFactory sessionFactory = null;          Session session = null;          Transaction transaction = null;          Student student = new Student();          Teacher teacher = new Teacher();          try {              configuration = new Configuration();              sessionFactory = configuration.configure().buildSessionFactory();              session = sessionFactory.openSession();              transaction = session.beginTransaction();              student.setName("shanshan");              student.setAge(25);              student.setCardId("123456");              teacher.setName("xiaolan");              teacher.setAge(25);              teacher.setSalary(5000);              session.save(student);              session.save(teacher);          } finally {              if (session != null) {                  transaction.commit();                  session.close();              }          }      }            public static void select(){          Configuration configuration = null;          SessionFactory sessionFactory = null;          Session session = null;          try {              configuration = new Configuration();              sessionFactory = configuration.configure().buildSessionFactory();              session = sessionFactory.openSession();              Query query = session.createQuery("from Person");              Iterator iterator = query.list().iterator();              while (iterator.hasNext()){                  Person person = (Person)iterator.next();                  System.out.println(person.getName());              }          } finally {              if (session != null) {                  session.close();              }          }      }  }

感谢各位的阅读，以上就是“Hibernate的继承关系是什么”的内容了，经过本文的学习后，相信大家对Hibernate的继承关系是什么这一问题有了更深刻的体会，具体使用情况还需要大家实践验证。这里是亿速云，小编将为大家推送更多相关知识点的文章，欢迎关注！