Hibernate，JPA注解@Version

Hibernate实现悲观锁和乐观锁。

1，悲观锁

用例代码如下：

• 数据库DDL语句：

• hibernate.cfg.xml

• java类

以上代码（除下面的main之外）同乐观锁。

main

 package a3_Version;
 import org.hibernate.LockOptions;
 import org.hibernate.Session;
 import daoUtil.HibernateUtil;

 public class Test_pessiLock {

     public static void main(String[] args) {
         Session session = HibernateUtil.getSession();

         try {
             Cat cat = (Cat)session.get(Cat.class, "8a6cc5a34c54de57014c54de588e0000", LockOptions.UPGRADE);

             System.out.println("这行设置断点，到数据库");
             System.out.println("使用SQL:select * from CAT t WHERE T.ID='"+cat.getId()+"' FOR UPDATE");
             System.out.println("验证CAT表，ID='"+cat.getId()+"'的行数据是否被锁住了。");
         } catch (RuntimeException e) {
             throw e;
         } finally {
             session.close();
         }
     }
 }

2，乐观锁

JPA通过@Version添加对表数据的乐观锁定的支持

根据EJB3规范,version列可以是numeric类型(推荐方式)也可以是timestamp类型. Hibernate支持任何自定义类型,只要该类型实现了UserVersionType.

用例代码如下：

• 数据库DDL语句：

 create table CAT
 (
   id          VARCHAR2(32 CHAR) not null,
   create_time TIMESTAMP(6),
   update_time TIMESTAMP(6),
   cat_name    VARCHAR2(255 CHAR),
   version     NUMBER(10) not null
 )

• hibernate.cfg.xml

 <?xml version="1.0" encoding="utf-8" ?>
 <!DOCTYPE hibernate-configuration
  PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN"
  "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
 <hibernate-configuration>
     <session-factory>
         <!-- 数据库驱动配置 -->
         <property name="dialect">org.hibernate.dialect.Oracle10gDialect</property>
         <property name="connection.driver_class">oracle.jdbc.OracleDriver</property>
         <property name="connection.url">jdbc:oracle:thin:@127.0.0.1:1521:orcl</property>
         <property name="connection.username">wxuatuser</property>
         <property name="connection.password">xlh</property>
         <property name="show_sql">true</property>
         <!-- 自动执行DDL属性是update，不是true -->
         <property name="hbm2ddl.auto">update</property>
         <!-- hibernate实体类 -->

         <mapping class="a3_Version.Cat"/>

     </session-factory>
 </hibernate-configuration>

• java类

实体类 - 基类

 package model;
 import java.io.Serializable;
 import java.util.Date;
 import javax.persistence.Column;
 import javax.persistence.GeneratedValue;
 import javax.persistence.Id;
 import javax.persistence.MappedSuperclass;
 import org.hibernate.annotations.GenericGenerator;
 /**
  * 实体类 - 基类
  */
 @MappedSuperclass
 public class BaseEntity implements Serializable {

     private static final long serialVersionUID = -6718838800112233445L;

     private String id;// ID
     private Date create_time;// 创建日期
     private Date update_time;// 修改日期
     @Id
     @Column(length = 32, nullable = true)
     @GeneratedValue(generator = "uuid")
     @GenericGenerator(name = "uuid", strategy = "uuid")
     public String getId() {
         return id;
     }
     public void setId(String id) {
         this.id = id;
     }
     @Column(updatable = false)
     public Date getCreate_time() {
         return create_time;
     }
     public void setCreate_time(Date create_time) {
         this.create_time = create_time;
     }
     public Date getUpdate_time() {
         return update_time;
     }
     public void setUpdate_time(Date update_time) {
         this.update_time = update_time;
     }
     @Override
     public int hashCode() {
         return id == null ? System.identityHashCode(this) : id.hashCode();
     }
     @Override
     public boolean equals(Object obj) {
         if (this == obj) {
             return true;
         }
         if (obj == null) {
             return false;
         }
         if (getClass().getPackage() != obj.getClass().getPackage()) {
             return false;
         }
         final BaseEntity other = (BaseEntity) obj;
         if (id == null) {
             if (other.getId() != null) {
                 return false;
             }
         } else if (!id.equals(other.getId())) {
             return false;
         }
         return true;
     }
 }

实体类

 package a3_Version;
 import javax.persistence.Entity;
 import javax.persistence.Version;
 import model.BaseEntity;
 import org.hibernate.annotations.DynamicInsert;
 import org.hibernate.annotations.DynamicUpdate;

 @Entity
 @DynamicInsert
 @DynamicUpdate
 public class Cat extends BaseEntity{
     /**
      * 实体类
      */
     private static final long serialVersionUID = -2776330321385582872L;

     private String cat_name;

     private int version;
     @Version
     public int getVersion() {
         return version;
     }

     public void setVersion(int version) {
         this.version = version;
     }

     public String getCat_name() {
         return cat_name;
     }

     public void setCat_name(String cat_name) {
         this.cat_name = cat_name;
     }
 }

Dao

 package daoUtil;
 import org.hibernate.HibernateException;
 import org.hibernate.Session;
 import org.hibernate.SessionFactory;
 import org.hibernate.Transaction;
 import org.hibernate.cfg.Configuration;
 import org.hibernate.service.ServiceRegistry;
 import org.hibernate.service.ServiceRegistryBuilder;

 public class HibernateUtil {

     private static final SessionFactory sessionFactory;

     static {
         try {
             Configuration cfg = new Configuration().configure();
             ServiceRegistry serviceRegistry = new ServiceRegistryBuilder()
                     .applySettings(cfg.getProperties()).buildServiceRegistry();
             sessionFactory = cfg.buildSessionFactory(serviceRegistry);
         } catch (Throwable ex) {
             throw new ExceptionInInitializerError(ex);
         }
     }

     public static Session getSession() throws HibernateException {
         return sessionFactory.openSession();
     }

     public static Object save(Object obj){
         Session session = HibernateUtil.getSession();
         Transaction tx = null;
         try {
             tx = session.beginTransaction();
             session.save(obj);
             tx.commit();
         } catch (RuntimeException e) {
             if (tx != null) {
                 tx.rollback();
             }
             throw e;
         } finally {
             session.close();
         }
         return obj;
     }

     public static void delete(Class<?> clazz,String id){
         Session session = HibernateUtil.getSession();
         Transaction tx = null;
         try {
             tx = session.beginTransaction();
             Object obj = session.get(clazz,id);
             session.delete(obj);
             tx.commit();
         } catch (RuntimeException e) {
             if (tx != null) {
                 tx.rollback();
             }
             throw e;
         } finally {
             session.close();
         }
     }
 }

main

 package a3_Version;
 import java.util.ArrayList;
 import java.util.Iterator;
 import org.hibernate.Session;
 import org.hibernate.StaleObjectStateException;
 import org.hibernate.Transaction;
 import a3_Version.Cat;
 import daoUtil.HibernateUtil;

 public class Test_optiLock extends Thread {

     private String transactionType;
     private Log log;
     private String id;

     public Test_optiLock(String transactionType, Log log,String id) {
         this.transactionType = transactionType;
         this.log = log;
         this.id = id;
     }

     public Test_optiLock() {}

     public void run() {
         try {
             if (transactionType.equals("modify"))
                 modify(id);
             else
                 update(id);
         } catch (Exception e) {
             e.printStackTrace();
         }
     }

     public void modify(String id) throws Exception {
         Session session = HibernateUtil.getSession();
         Transaction tx = null;
         try {
             tx = session.beginTransaction();
             log.write("modify():开始事务");
             Thread.sleep(500);

             Cat cat = (Cat) session.get(Cat.class, id);

             log.write("modify():查询到cat_name为:" + cat.getCat_name());
             Thread.sleep(500);

             cat.setCat_name(cat.getCat_name()+"modify");
             log.write("modify():把cat_name改为：" + cat.getCat_name());

             tx.commit();
             log.write("modify():提交事务");
             Thread.sleep(500);
         } catch (StaleObjectStateException e) {
             if (tx != null) {
                 tx.rollback();
             }
             e.printStackTrace();
             System.out.println("cat_name已被其他事务修改,本事务被撤销，请重新开始modify事务");
             log.write("modify():cat_name已被其他事务修改,本事务被撤销");
         } catch (RuntimeException e) {
             if (tx != null) {
                 tx.rollback();
             }
             throw e;
         } finally {
             session.close();
         }
     }

     public void update(String id) throws Exception {
         Session session = HibernateUtil.getSession();
         Transaction tx = null;
         try {
             tx = session.beginTransaction();
             log.write("update():开始事务");
             Thread.sleep(500);

             Cat cat = (Cat) session.get(Cat.class, id);

             log.write("update():查询到cat_name为:" + cat.getCat_name());
             Thread.sleep(500);

             cat.setCat_name(cat.getCat_name()+"update");
             log.write("update():把cat_name改为：" + cat.getCat_name());

             tx.commit();
             log.write("update():提交事务");
             Thread.sleep(500);
         } catch (StaleObjectStateException e) {
             if (tx != null) {
                 tx.rollback();
             }
             e.printStackTrace();
             System.out.println("cat_name已被其他事务修改,本事务被撤销，请重新开始update事务");
             log.write("update():cat_name已被其他事务修改,本事务被撤销");
         } catch (RuntimeException e) {
             if (tx != null) {
                 tx.rollback();
             }
             throw e;
         } finally {
             session.close();
         }
     }

     public static void main(String args[]) throws Exception {
         Cat cat = new Cat();
         cat.setCat_name("test3@optiLock");
         HibernateUtil.save(cat);

         Log log = new Log();
         String id = cat.getId();
         Thread modifyThread = new Test_optiLock("modify", log ,id);
         Thread updateThread = new Test_optiLock("update", log ,id);

         modifyThread.start();
         updateThread.start();

         while (modifyThread.isAlive() || updateThread.isAlive()) {
             Thread.sleep(100);
         }
         log.print();
     }
 }

 class Log {
     private ArrayList<String> logs = new ArrayList<String>();

     synchronized void write(String text) {
         logs.add(text);
     }

     public void print() {
         for (Iterator<String> it = logs.iterator(); it.hasNext();) {
             System.out.println(it.next());
         }
     }
 }

执行后控制台信息如下：

Hibernate: insert into Cat (cat_name, version, id) values (?, ?, ?)
Hibernate: select cat0_.id as id1_0_0_, cat0_.create_time as create_t2_0_0_, cat0_.update_time as update_t3_0_0_, cat0_.cat_name as cat_name4_0_0_, cat0_.version as version5_0_0_ from Cat cat0_ where cat0_.id=?
Hibernate: select cat0_.id as id1_0_0_, cat0_.create_time as create_t2_0_0_, cat0_.update_time as update_t3_0_0_, cat0_.cat_name as cat_name4_0_0_, cat0_.version as version5_0_0_ from Cat cat0_ where cat0_.id=?
Hibernate: update Cat set cat_name=?, version=? where id=? and version=?
Hibernate: update Cat set cat_name=?, version=? where id=? and version=?
org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect): [a3_Version.Cat#8a6cc5a34c6ea5f2014c6ea5f3740000]
	at org.hibernate.persister.entity.AbstractEntityPersister.check(AbstractEntityPersister.java:2523)
	at org.hibernate.persister.entity.AbstractEntityPersister.update(AbstractEntityPersister.java:3242)
	at org.hibernate.persister.entity.AbstractEntityPersister.updateOrInsert(AbstractEntityPersister.java:3140)
	at org.hibernate.persister.entity.AbstractEntityPersister.update(AbstractEntityPersister.java:3470)
	at org.hibernate.action.internal.EntityUpdateAction.execute(EntityUpdateAction.java:140)
	at org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:393)
	at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:385)
	at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:302)
	at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:339)
	at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:52)
	at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1240)
	at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:404)
	at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.beforeTransactionCommit(JdbcTransaction.java:101)
	at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.commit(AbstractTransactionImpl.java:175)
	at a3_Version.Test_optiLock.update(Test_optiLock.java:87)
	at a3_Version.Test_optiLock.run(Test_optiLock.java:29)
cat_name已被其他事务修改,本事务被撤销，请重新开始update事务
modify():开始事务
update():开始事务
modify():查询到cat_name为:test3@optiLock
update():查询到cat_name为:test3@optiLock
modify():把cat_name改为：test3@optiLockmodify
update():把cat_name改为：test3@optiLockupdate
modify():提交事务
update():cat_name已被其他事务修改,本事务被撤销

　　数据库层面，存入数据时，version是0，update后是1。

环境：JDK1.6，MAVEN

源码地址：http://files.cnblogs.com/files/xiluhua/hibernate%40Version.rar