Hibernate自关联关系

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Hibernate自关联关系

业务逻辑：

书籍的种类，本身是自关联的关系，如下图所示：

所有书籍：

历史书籍

音乐书籍

钢琴书籍

烹饪书籍

美食书籍

1. Books类的源程序

Books.java

package mypack;

import java.util.Set;

import java.io.Serializable;

public class Books

implements Serializable {

/**

* 默认构造函数

public Books() {

}

/** 主健id */

private Long id;

/** 书籍名称 */

private String name;

/** 父书籍 */

private mypack.Books parentCategory;

/** 子集合 */

private Set childCategories;

/** 完整构造函数 */

public Books(String name, mypack.Books parentCategory, Set childCategories) {

this.name = name;

this.parentCategory = parentCategory;

this.childCategories = childCategories;

}

/** 最小构造函数 */

public Books(Set childCategories) {

this.childCategories = childCategories;

}

public Long getId() {

return this.id;

}

public void setId(Long id) {

this.id = id;

}

public String getName() {

return this.name;

}

public void setName(String name) {

this.name = name;

}

public mypack.Books getParentCategory() {

return this.parentCategory;

}

public void setParentCategory(mypack.Books parentCategory) {

this.parentCategory = parentCategory;

}

public Set getChildCategories() {

return this.childCategories;

}

public void setChildCategories(Set childCategories) {

this.childCategories = childCategories;

}

2. 映射文件，放在classes/mypack下

Books.hbm.xml

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping

PUBLIC "-//Hibernate/Hibernate Mapping DTD 2.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping >

</id>

</property>

<set

name="childCategories"

cascade="save-update"

inverse="true"

<one-to-many class="mypack.Books" />

</set>

<many-to-one

name="parentCategory"

column="CATEGORY_ID"

class="mypack.Books"

cascade="save-update"

</class>

</hibernate-mapping>

3. 数据库Schema

数据库Schema

Create table books(

Id number(10) not null,

Name varchar2(64),

Category_id number(10),

Primary key(id)

);

1. hibernate.property

hibernate.property

hibernate.dialect net.sf.hibernate.dialect.Oracle9Dialect

hibernate.dialect net.sf.hibernate.dialect.OracleDialect

hibernate.connection.driver_class oracle.jdbc.driver.OracleDriver

hibernate.connection.username testpm

hibernate.connection.password testpm

hibernate.connection.url jdbc:oracle:thin:@localhost:1521:wsy

4. 业务操作类BusinessService.java

package mypack;

import net.sf.hibernate.SessionFactory;

import net.sf.hibernate.cfg.Configuration;

import net.sf.hibernate.*;

import java.util.HashSet;

import java.util.List;

public class BusinessService {

public static SessionFactory sessionFactory;

static{

try{

// Create a configuration based on the properties file we've put

Configuration config = new Configuration();

config.addClass(Books.class);

// Get the session factory we can use for persistence

sessionFactory = config.buildSessionFactory();

}catch(Exception e){e.printStackTrace();}

}

public BusinessService() {

}

/**

* 级联保存

* @throws Exception

public void saveCategoryWithCascade() throws Exception{

Session session = sessionFactory.openSession();

Transaction tx = null;

try {

tx = session.beginTransaction();

Books allBooks = new Books("allbooks",null,new HashSet());

Books historyBooks = new Books("history",null,new HashSet());

Books musicBooks =new Books("music",null,new HashSet());

Books cookBooks=new Books("cook",null,new HashSet());

Books pianoBooks=new Books("piano",null,new HashSet());

Books foodBooks=new Books("food",null,new HashSet());

//建立所有书与历史书的关系

allBooks.getChildCategories().add(historyBooks);

historyBooks.setParentCategory(allBooks);

//建立所有书与音乐书的关系

allBooks.getChildCategories().add(musicBooks);

musicBooks.setParentCategory(allBooks);

//建立所有书与烹饪书的关系

allBooks.getChildCategories().add(cookBooks);

cookBooks.setParentCategory(allBooks);

//建立音乐书与钢琴书的关系

musicBooks.getChildCategories().add(pianoBooks);

pianoBooks.setParentCategory(musicBooks);

//建立烹饪书与美食书的关系

foodBooks.setParentCategory(cookBooks);

cookBooks.getChildCategories().add(foodBooks);

session.save(allBooks);

tx.commit();

}catch (Exception e) {

if (tx != null) {

// Something went wrong; discard all partial changes

tx.rollback();

}

throw e;

} finally {

// No matter what, close the session

session.close();

}

/**

* 修改关系

* @throws Exception

public void modifyCategoryAssociation() throws Exception{

Session session = sessionFactory.openSession();

Transaction tx = null;

try {

tx = session.beginTransaction();

Books cookBooks =findCategoryByName(session,"cook");

Books foodBooks=findCategoryByName(session,"food");

Books musicBooks=findCategoryByName(session,"music");

//建立西红柿类和蔬菜类之间的关联关系

foodBooks.setParentCategory(musicBooks);

musicBooks.getChildCategories().add(foodBooks);

//删除西红柿类和水果类之间的关联关系

cookBooks.getChildCategories().remove(foodBooks);

tx.commit();

}catch (Exception e) {

if (tx != null) {

// Something went wrong; discard all partial changes

tx.rollback();

}

throw e;

} finally {

// No matter what, close the session

session.close();

}

/**

* 根据名称，得到bean

* @param session Session

* @param name String

* @throws Exception

* @return Books

private Books findCategoryByName(Session session,String name)throws Exception{

List results=session.find("from Books as c where c.name='"+name+"'");

return (Books)results.iterator().next();

}

/**

* 主方法，运行

* @param args String[]

* @throws Exception

public static void main(String[] args)throws Exception{

new BusinessService().test();

sessionFactory.close();

}

/**

* 测试方法

* @throws Exception

private void test()throws Exception {

saveCategoryWithCascade();

modifyCategoryAssociation();

}

目录结构示意：

Classes

Hibernate.property

/mypack

Books.java

BusinessService.java

Books.hbm.xml

参考资料：精通Hibernate:Java对象持久化技术详解孙卫琴