hibernate删除的理解

customer2的配置文件

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!--
Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
<class name="com.bsw.job.Customer2" table="customer2" catalog="hibernateex">
<id name="id" type="java.lang.Integer">
<column name="id" />
<generator class="native" />
</id>
<property name="name" type="java.lang.String">
<column name="name" length="20" />
</property>
<property name="age" type="java.lang.Integer">
<column name="age" />
</property>
<property name="email" type="java.lang.String">
<column name="email" length="30" />
</property>
<property name="address" type="java.lang.String">
<column name="address" length="30" />
</property>
</class>
</hibernate-mapping>

Customer2DAO 类

package com.bsw.job;

import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.hibernate.LockMode;
import org.hibernate.Query;
import org.hibernate.Transaction;
import org.hibernate.criterion.Example;

import com.sun.org.apache.bcel.internal.generic.GETSTATIC;

/**
* Data access object (DAO) for domain model class Customer2.
*
* @see com.bsw.job.Customer2
* @author MyEclipse Persistence Tools
*/

public class Customer2DAO extends BaseHibernateDAO {
private static final Log log = LogFactory.getLog(Customer2DAO.class);

public List selectCustomer(String name){
String hql="from Customer2 where name =:name order by age";
Query query =getSession().createQuery(hql);
query.setParameter("name", name);
List list=query.list();
return list;

}

public List selectAllCustomer(){
String hql="from Customer2 order by age";
Query query =getSession().createQuery(hql);

List list=query.list();
return list;

}

public void deleteCustomer(Customer2 customer){
Transaction tr=getSession().beginTransaction();
getSession().delete(customer);
tr.commit();
getSession().close();
}

public void updateCustomer(Customer2 customer){
Transaction tr=getSession().beginTransaction();
getSession().saveOrUpdate(customer);
tr.commit();
getSession().close();
}

public void addCustomer(Customer2 customer){
Transaction tr=getSession().beginTransaction();
getSession().save(customer);
tr.commit();
getSession().close();
}
public void save(Customer2 transientInstance) {
log.debug("saving Customer2 instance");
try {
getSession().save(transientInstance);
log.debug("save successful");
} catch (RuntimeException re) {
log.error("save failed", re);
throw re;
}
}

public void delete(Customer2 persistentInstance) {
log.debug("deleting Customer2 instance");
try {
Transaction tr=getSession().beginTransaction();
getSession().delete(persistentInstance);
tr.commit();
log.debug("delete successful");
} catch (RuntimeException re) {
log.error("delete failed", re);
throw re;
}
}

public Customer2 findById(java.lang.Integer id) {
log.debug("getting Customer2 instance with id: " + id);
try {
Customer2 instance = (Customer2) getSession().get(
"com.bsw.job.Customer2", id);
return instance;
} catch (RuntimeException re) {
log.error("get failed", re);
throw re;
}
}

public List findByExample(Customer2 instance) {
log.debug("finding Customer2 instance by example");
try {
List results = getSession().createCriteria("com.bsw.job.Customer2")
.add(Example.create(instance)).list();
log.debug("find by example successful, result size: "
+ results.size());
return results;
} catch (RuntimeException re) {
log.error("find by example failed", re);
throw re;
}
}

public List findByProperty(String propertyName, Object value) {
log.debug("finding Customer2 instance with property: " + propertyName
+ ", value: " + value);
try {
String queryString = "from Customer2 as model where model."
+ propertyName + "= ?";
Query queryObject = getSession().createQuery(queryString);
queryObject.setParameter(0, value);
return queryObject.list();
} catch (RuntimeException re) {
log.error("find by property name failed", re);
throw re;
}
}

public List findAll() {
log.debug("finding all Customer2 instances");
try {
String queryString = "from Customer2";
Query queryObject = getSession().createQuery(queryString);
return queryObject.list();
} catch (RuntimeException re) {
log.error("find all failed", re);
throw re;
}
}

public Customer2 merge(Customer2 detachedInstance) {
log.debug("merging Customer2 instance");
try {
Customer2 result = (Customer2) getSession().merge(detachedInstance);
log.debug("merge successful");
return result;
} catch (RuntimeException re) {
log.error("merge failed", re);
throw re;
}
}

public void attachDirty(Customer2 instance) {
log.debug("attaching dirty Customer2 instance");
try {
getSession().saveOrUpdate(instance);
log.debug("attach successful");
} catch (RuntimeException re) {
log.error("attach failed", re);
throw re;
}
}

public void attachClean(Customer2 instance) {
log.debug("attaching clean Customer2 instance");
try {
getSession().lock(instance, LockMode.NONE);
log.debug("attach successful");
} catch (RuntimeException re) {
log.error("attach failed", re);
throw re;
}
}
}

测试类

package com.bsw.test;

import java.util.List;

import com.bsw.job.Customer2;
import com.bsw.job.Customer2DAO;

public class TestCustomer2 {
public static void main(String[] args) {
Customer2DAO dao=new Customer2DAO();
List<Customer2> list=(List<Customer2>)dao.selectAllCustomer();
System.out.println("按年龄从小到大排：");
System.out.println("用户ID "+"姓名 "+"年龄 "+"邮箱 "+"地址");
//for(Customer2 customer:list){
Customer2 customer=new Customer2();
customer.setAddress("上帝");
customer.setAge(25);
dao.addCustomer(customer);
Customer2 customer1=new Customer2();
//dao.getSession().get("customer1", 7);
customer1.setAddress("上帝");//在此处用这样就删不掉，还会报错，因为没有持久化，但如果用customer1.setId(7);的话就不会报错，因为在session.delete()方法中可以根据id把你所传的customer1给内部持久化。
dao.deleteCustomer(customer1);
//}
}
}