转载个常用的 Hibernate自关联关系

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

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