知识大全 Hibernate一对多双向映射及乐观锁使用

Posted 2022-07-18 班级

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　　在 Hibernate关联关系映射实例速查一文中通过myeclipse 快速做出了Hibernate各种映射的示例时隔快一年了但是还是有博友向我索要工程源码很遗憾的是已经找不到了但找到一了一个测试代码对双向关联和乐观锁的测试其实映射类型很多搞清楚一对多基本上所有的映射就搞明白了一对一也是一对多的特例而已多对多也可以转换为一对多和多对一并且实际中很少用到多对多

　　还是老规矩因为是测试代码几乎全部是myeclipse生成的我稍作了修改并且应博友阿飞的留言我做了详细的注释

　　例子两部分一对多双向映射模型是班级－学生模型两个实体分别是Tclass和Student 乐观锁的是使用版本分别使用递增整数和时间戳两个实体分别是Foo和Bar

　　Tclass实体及其映射 public class Tclass implements java io Serializable

　　// Fields

　　private Long cid;

　　private String cname;

　　private Set students = new HashSet( );

　　// Constructors // Property accessors

　　public String toString() return Tclass + cid= + cid + cname= + cname + \\ + ;

　　Student实体及其映射 public class Student implements java io Serializable

　　// Fields

　　private Long sid;

　　private Tclass tclass;

　　private String sname;

　　// Constructors // Property accessors

　　public String toString() return Student + sid= + sid + sname= + sname + \\ + ;

　　测试班级学生模型 public class Test

　　/** * @param args */ public static void main(String[] args) testSave(); // testDeleteTclass();

　　public static void testSave() Tclass c = new Tclass(); c setCname( 某班级 ); Student s = new Student(); Student s = new Student(); s setSname( 张三 ); s setTclass(c); s setSname( 李四 ); s setTclass(c); c getStudents() add(s ); c getStudents() add(s );

　　Session session = HibernateSessionFactory getSession(); Transaction tx = session beginTransaction(); session save(c); mit(); session close();

　　public static void testUpdateClass() System out println( 正在调用testUpdateClass() ); Session session = HibernateSessionFactory getSession(); Tclass c = (Tclass) session load(Tclass class Long valueOf( L)); System out println(c); c setCname( 班级更名 ); session beginTransaction(mit();

public static void testUpdateStudent() System out println( 正在调用testUpdateStudent() ); Session session = HibernateSessionFactory getSession(); Tclass c = (Tclass) session load(Tclass class Long valueOf( L)); Student s = (Student) session load(Student class Long valueOf( L)); s setSname( 学生改名换姓王八 ); s setTclass(c); System out println(c); System out println(s); session beginTransaction(mit(); System out println(s); System out println(s getTclass());

　　public static void testDeleteStudent() System out println( 正在调用testDelete() ); Session session = HibernateSessionFactory getSession(); Student s = (Student) session load(Student class Long valueOf( L)); System out println(s); System out println(s getTclass()); session delete(s); session beginTransaction(mit();

　　public static void testDeleteTclass() System out println( 正在调用testDelete() ); Session session = HibernateSessionFactory getSession(); Tclass c = (Tclass) session load(Tclass class Long valueOf( L)); System out println(c); session delete(c); session beginTransaction(mit();

　　public static void testQueryClass() System out println( 正在调用testQueryClass() ); Session session = HibernateSessionFactory getSession(); Tclass c = (Tclass) session load(Tclass class new Long( )); System out println(c); System out println(c getStudents());

　　public static void testQueryStudent() System out println( 正在调用testQueryStudent() ); Session session = HibernateSessionFactory getSession(); Student s = (Student) session load(Student class new Long( )); System out println(s); System out println(s getTclass());

　　下面是乐观锁的使用基于整数的版本控制

　　Foo实体和映射文件 public class Foo implements java io Serializable

　　// Fields

　　private Long pid;

　　private Integer version;

　　private String name;

　　// Constructors // Property accessors

　　public String toString() return Foo + pid= + pid + version= + version + name= + name + \\ + ;

　　测试 public class TestFoo

　　/** * @param args */ public static void main(String[] args) testSave();

　　 public static void testSave() Foo foo = new Foo( foo );

　　Session session = HibernateSessionFactory getSession(); session save(foo ); session beginTransaction(mit(); session close();

　　基于时间戳的版本控制 public class Bar implements java io Serializable Comparable

　　// Fields

　　private Long id; private Date timestamp; private String name;

　　// Constructors // Property accessors

　　public String toString() return Bar + id= + id + timestamp= + timestamp + name= + name + \\ + ;

　　/** * 排序接口方法实现为了能对查询结果按照id的大小进行排序 * @param o 排序对象 * @return 比较值 */ public int pareTo(Object o) Bar bar = (Bar) o; Long res = this id bar getId(); return res intValue();

　　public class TestBar public static void main(String args[]) testUpdateBar(); testQueryBar();

　　public static void testSaveBar() Bar bar = new Bar( bar ); Session session = HibernateSessionFactory getSession(); session save(bar); session beginTransaction(mit(); session close();

　　public static void testQueryBar() Session session = HibernateSessionFactory getSession(); String hql = from Bar ; Query query = session createQuery(hql); List<Bar> barList = query list(); Collections sort(barList); for (Bar bar : barList) System out println(bar getId() + :\\t + bar getTimestamp() getTime()); session close();

　　public static void testUpdateBar() Session session = HibernateSessionFactory getSession(); String hql = from Bar ; Query query = session createQuery(hql); List<Bar> barList = query list(); for (Bar bar : barList) bar setName( newBar ); session beginTransaction(mit(); session close();

　　public class TestStack public static void main(String args[]) test(); public static void test() Stack stack = new Stack(); String s = ; String s = ; String s = ; String s = ; stack push(s ); stack push(s ); stack push(s ); stack push(s );

　　for(;!stack isEmpty();) System out println(stack pop());

　　//for语句先判断是否符合条件然后确定是否执行循环 for(int i= ;i> ;i ) System out println( >>> +i);

　　下面是SessionFactory工具和hibernate配置文件 import hibernate HibernateException; import hibernate Session; import hibernate cfg Configuration;

　　/** * Configures and provides access to Hibernate sessions tied to the * current thread of execution Follows the Thread Local Session * pattern see @link */ public class HibernateSessionFactory

　　/** * Location of hibernate cfg xml file * Location should be on the classpath as Hibernate uses * #resourceAsStream style lookup for its configuration file * The default classpath location of the hibernate config file is * in the default package Use #setConfigFile() to update * the location of the configuration file for the current session */ private static String CONFIG_FILE_LOCATION = /hibernate cfg xml ; private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>(); private static Configuration configuration = new Configuration(); private static hibernate SessionFactory sessionFactory; private static String configFile = CONFIG_FILE_LOCATION;

　　static try nfigure(configFile); sessionFactory = configuration buildSessionFactory(); catch (Exception e) System err println( %%%% Error Creating SessionFactory %%%% ); e printStackTrace(); private HibernateSessionFactory()

　　/** * Returns the ThreadLocal Session instance Lazy initialize * the <code>SessionFactory</code> if needed * * @return Session * @throws HibernateException */ public static Session getSession() throws HibernateException Session session = (Session) threadLocal get();

　　if (session == null || !session isOpen()) if (sessionFactory == null) rebuildSessionFactory(); session = (sessionFactory != null) ? sessionFactory openSession() : null; threadLocal set(session);

　　return session;

　　/**

* Rebuild hibernate session factory * */ public static void rebuildSessionFactory() try nfigure(configFile); sessionFactory = configuration buildSessionFactory(); catch (Exception e) System err println( %%%% Error Creating SessionFactory %%%% ); e printStackTrace();

　　/** * Close the single hibernate session instance * * @throws HibernateException */ public static void closeSession() throws HibernateException Session session = (Session) threadLocal get(); threadLocal set(null);

　　if (session != null) session close();

　　/** * return session factory * */ public static hibernate SessionFactory getSessionFactory() return sessionFactory;

　　/** * return session factory * * session factory will be rebuilded in the next call */ public static void setConfigFile(String configFile) HibernanfigFile = configFile; sessionFactory = null;

　　/** * return hibernate configuration * */ public static Configuration getConfiguration() return configuration;

　　<?xml version= encoding= UTF ?> <!DOCTYPE hibernate configuration PUBLIC //Hibernate/Hibernate Configuration DTD //EN configuration dtd >

　　<! Generated by MyEclipse Hibernate Tools > <hibernate configuration>

　　<session factory> <property name= connection username >root</property> <property name= connection url > jdbc:mysql://localhost: /testdb </property> <property name= dialect > hibernate dialect MySQLDialect </property> <property name= nnection profile > mysql jdbc Driver </property> <property name= connection password >leizhimin</property> <property name= connection driver_class > mysql jdbc Driver </property> <property name= show_sql >true</property> <! <property name= format_sql >true</property> > <property name= hbm ddl auto >create</property>

　　</session factory>

　　</hibernate configuration>

　　数据库用的是mysql sql脚本我导出了一份如下 /* SQLyog Enterprise MySQL GUI v MySQL munity nt : Database testdb ********************************************************************* */

　　/*! SET NAMES utf */;

　　/*! SET SQL_MODE= */;

　　/*! SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS FOREIGN_KEY_CHECKS= */; /*! SET @OLD_SQL_MODE=@@SQL_MODE SQL_MODE= NO_AUTO_VALUE_ON_ZERO */;

　　create database if not exists testdb;

　　USE testdb;

　　/*Table structure for table bar */

　　DROP TABLE IF EXISTS bar;

　　CREATE TABLE bar ( id bigint( ) NOT NULL auto_increment timestamp datetime NOT NULL name varchar( ) NOT NULL PRIMARY KEY (id) ) ENGINE=InnoDB DEFAULT CHARSET=gbk;

　　/*Table structure for table foo */

　　DROP TABLE IF EXISTS foo;

　　CREATE TABLE foo ( pid bigint( ) NOT NULL auto_increment version int( ) NOT NULL name varchar( ) NOT NULL PRIMARY KEY (pid) ) ENGINE=InnoDB DEFAULT CHARSET=gbk;

　　/*Table structure for table student */

　　DROP TABLE IF EXISTS student;

　　CREATE TABLE student ( sid bigint( ) NOT NULL auto_increment fk_cid bigint( ) NOT NULL sname varchar( ) NOT NULL PRIMARY KEY (sid) KEY FK FFE B AA (fk_cid) CONSTRAINT FK FFE B AA FOREIGN KEY (fk_cid) REFERENCES tclass (cid) ) ENGINE=InnoDB AUTO_INCREMENT= DEFAULT CHARSET=gbk;

　　/*Table structure for table tclass */

　　DROP TABLE IF EXISTS tclass;

　　CREATE TABLE tclass ( cid bigint( ) NOT NULL auto_increment cname varchar( ) NOT NULL PRIMARY KEY (cid) ) ENGINE=InnoDB AUTO_INCREMENT= DEFAULT CHARSET=gbk;

　　/*! SET SQL_MODE=@OLD_SQL_MODE */; /*! SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;

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