Hibernate逍遥游记-第15章处理并发问题-003乐观锁

1.

2.

 drop database if exists SAMPLEDB;
 create database SAMPLEDB;
 use SAMPLEDB;

 drop table if exists  MONKEYS ;
 create table MONKEYS(
    ID bigint not null,
    NAME varchar(15),
    COUNT int,
    VERSION integer,
    primary key (ID)
 )  type=INNODB;

 insert into MONKEYS(ID,NAME,COUNT,VERSION) values(1,'智多星',1000,0);

3.

 package mypack;

 public class Monkey{

     private Long id;

     private String name;

     private int count;

     private int version;

     public Monkey(String name, int count) {
         this.name = name;
         this.count = count;
     }

     public Monkey() {
     }

     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 int getCount() {
         return this.count;
     }

     public void setCount(int count) {
         this.count = count;
     }

     public int getVersion() {
         return this.version;
     }

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

4.

 <?xml version="1.0"?>
 <!DOCTYPE hibernate-mapping
 PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
 <hibernate-mapping >

   <class name="mypack.Monkey" table="MONKEYS" >
     <id name="id" type="long" column="ID">
       <generator class="increment"/>
     </id>

     <version name="version" column="VERSION" />

     <property name="name" type="string" >
         <column name="NAME" length="15" />
     </property>

     <property name="count" type="int" column="COUNT" />

   </class>
 </hibernate-mapping>

5.

 package mypack;

 import org.hibernate.*;
 import org.hibernate.cfg.Configuration;
 import java.util.*;

 public class BusinessService extends Thread{
   public static SessionFactory sessionFactory;
   static{
      try{
        Configuration config = new Configuration();
        config.addClass(Monkey.class);

        sessionFactory = config.buildSessionFactory();
     }catch(RuntimeException e){e.printStackTrace();throw e;}
   }

   private Log log;

   public BusinessService(String name,Log log){
     super(name);
     this.log=log;
   }   

   public void run(){
    try{
     vote();
    }catch(Exception e){
      e.printStackTrace();
    }
   }  

   public void vote()throws Exception{
     Session session = sessionFactory.openSession();
     Transaction tx = null;
     try {

       tx = session.beginTransaction();
       log.write(getName()+":开始事务");
       Thread.sleep(500);

       Monkey monkey=(Monkey)session.get(Monkey.class,new Long(1));
       log.write(getName()+":查询到智多星的票数为"+monkey.getCount());
       Thread.sleep(500);

       monkey.setCount(monkey.getCount()+1);
       log.write(getName()+":把智多星的票数改为"+monkey.getCount());
       Thread.sleep(500);

       tx.commit();
       log.write(getName()+":提交事务");
       Thread.sleep(500);

     }catch(StaleObjectStateException e){
        if (tx != null) {
         tx.rollback();
        }
        e.printStackTrace();
        System.out.println(getName()+":智多星票数已被其他事务修改,本事务被撤销，请重新开始投票事务");
        log.write(getName()+":智多星票数已被其他事务修改,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 {
     Log log=new Log();
     Thread thread1=new BusinessService("猴子甲投票事务",log);
     Thread thread2=new BusinessService("猴子乙投票事务",log);

     thread1.start();
     thread2.start();

     while(thread1.isAlive() ||thread2.isAlive()){
      Thread.sleep(100);
     }
     log.print();
     sessionFactory.close();
   }
 }

 class Log{
   private ArrayList logs=new ArrayList();

   synchronized void write(String text){
     logs.add(text);
   }
   public void print(){
      for (Iterator it = logs.iterator(); it.hasNext();) {
          System.out.println(it.next());
       }
   }
 } 

6.

 hibernate.dialect=org.hibernate.dialect.MySQLDialect
 hibernate.connection.driver_class=com.mysql.jdbc.Driver
 hibernate.connection.url=jdbc:mysql://localhost:3306/sampledb
 hibernate.connection.username=root
 hibernate.connection.password=1234
 hibernate.show_sql=true
 hibernate.connection.isolation=2

7.使用timestamp

8.实现乐观锁的其他方法

9.