hibernate实例简析-hibernate_optimistic_locking

乐观锁

大多数基于数据版本记录机制（version）实现，一般是在数据库表中加入一个version字段
读取数据时将版本号一同读出，之后更新数据时版本号加一，如果提交数据时版本号小于或等于数据表中
的版本号，则认为数据是过期的，否则给予更新
===
Inventory inv = (Inventory)session.load(Inventory.class, 1);
System.out.println("itemName=" + inv.getItemName());
System.out.println("version=" + inv.getVersion());
System.out.println("quantity=" + inv.getQuantity());
inv.setQuantity(inv.getQuantity() - 200);
session.update(inv);
---
Inventory inv = (Inventory)session.load(Inventory.class, 1);
System.out.println("itemName=" + inv.getItemName());
System.out.println("version=" + inv.getVersion());
System.out.println("quantity=" + inv.getQuantity());
inv.setQuantity(inv.getQuantity() - 200);
session.update(inv);
===
<hibernate-mapping>
<class name="com.bjsxt.hibernate.Inventory" table="t_inventory" optimistic-lock="version">
<id name="itemNo">
<generator class="native"/>
</id>
<version name="version"/>
<property name="itemName"/>
<property name="quantity"/>
</class>
</hibernate-mapping>
===
public class Inventory {

private int itemNo;

private String itemName;

private int quantity;

private int version;
===
Inventory inv = new  Inventory();
inv.setItemNo(1001);
inv.setItemName("脑白金");
inv.setQuantity(1000);

session.save(inv);