save()
get/load()
——
get在被調用之後,立刻向數據庫發送sql語句
load被調用後會返回一個代理對象,改代理對象只保存了實體對象的id,
直到使用對象的非主鍵屬性時纔會向數據庫發出sql語句
——
查詢不存在的數據時
get返回null
load拋出異常org.hibernate.ObjectNotFoundExcption
update()
delect()
Hibernate單表映射
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- Generated 2016-4-20 15:32:23 by Hibernate Tools 3.5.0.Final -->
<hibernate-mapping>
<class name="Student" table="STUDENT">
<id name="sid" type="int">
<column name="SID" />
<generator class="assigned" />
</id>
<property name="name" type="java.lang.String">
<column name="NAME" />
</property>
<property name="gender" type="java.lang.String">
<column name="GENDER" />
</property>
<property name="birthday" type="java.util.Date">
<column name="BIRTHDAY" />
</property>
<property name="address" type="java.lang.String">
<column name="ADDRESS" />
</property>
</class>
</hibernate-mapping>
單一主鍵生成策略: <generator class="assigned" />
assign :由Java應用程序負責生成
native :由底層數據庫自動生成標識符(MySQL:increment,Oracle:sequence)