Hibernate 3.2 学习笔记 映射集合类

映射值属性集合类
值属性集合类没有单独的OID和生命周期 实体类集合有单独的OID和生命周期
set 不允许重复
属性:

name 指定集合的属性名

table 对应的 表

lazy 延迟检索策略

inverese 有较好的update性能 但是不会按照one方来同步更新数据库(要注意)
order-by 数据库排序方式
sort 内存排序方式

元素:

<key> 定义外键

<one-to-many> 定义many 方的类

<element column="***" type="string" not-null="true"/>

注： 由于采用了延时检索策略 所以在读取的时候
用hibernate.isInitialized(Object)检查
用hibernate.initialize(java.lang.Object proxy) 来初始化集合

< set name ="images" table ="IMAGES"
inverse ="false"
cascade ="save-update"
lazy ="true" >
< key column ="CUSTOMER_ID" />
< element column ="FILENAME" type ="string" not-null ="true" />
</ set >

例子
Customer.hbm.xm

<? xmlversion="1.0" ?>
<! DOCTYPEhibernate-mappingPUBLIC
"-//Hibernate/HibernateMappingDTD3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >

< hibernate-mapping >

< class name ="ergal.Customer" table ="CUSTOMERS" lazy ="true" >
< id name ="id" type ="long" column ="ID" >
< generator class ="native" />
</ id >

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

< property name ="age" column ="AGE" type ="int" />


< set name ="images" table ="IMAGES"
inverse ="false"
cascade ="save-update"
lazy ="true" >
< key column ="CUSTOMER_ID" />
< element column ="FILENAME" type ="string" not-null ="true" />
</ set >

</ class >

</ hibernate-mapping >

运行hbm2ddl
两表
Customer
1 - ID
2 - NAME
3 - AGE
IMAGES
1 - CUSTOMER_ID
2 - FILENAME

测试代码
BusinessService.java

package ergal;

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

public class BusinessService
... {
publicstaticSessionFactorysessionFactory;
static
...{
try
...{
Configurationconfig=newConfiguration();
sessionFactory=config.configure().buildSessionFactory();
}
catch(Exceptione)
...{
e.printStackTrace();
}
}

publicvoidsaveCustomer(Objectcustomer)throwsException
...{
Sessionsession=sessionFactory.openSession();
Transactiontx=null;
try
...{
tx=session.beginTransaction();
session.save(customer);
tx.commit();
}
catch(Exceptione)
...{
if(tx!=null)
...{
tx.rollback();
}
throwe;
}
finally
...{
session.close();
}
}

publicCustomerloadCustomer(Longid)throwsException
...{
Sessionsession=sessionFactory.openSession();
Transactiontx=null;
try
...{
tx=session.beginTransaction();

Customercustomer=(Customer)session.load(Customer.class,id);
Hibernate.initialize(customer.getImages());


tx.commit();
returncustomer;
}
catch(Exceptione)
...{
if(tx!=null)
...{
tx.rollback();
}
throwe;
}
finally
...{
session.close();
}
}

publicvoidtest()throwsException
...{
Setimages=newHashSet();
images.add("image1.jpg");
images.add("image4.jpg");
images.add("image2.jpg");
images.add("image5.jpg");

Customercustomer=newCustomer("Tom",21,images);
saveCustomer(customer);

Customerc=loadCustomer(newLong(1));
System.out.println(customer.getImages().getClass().getName());

Iteratorit=customer.getImages().iterator();

while(it.hasNext())
...{
Stringfilename=(String)it.next();
System.out.println(customer.getName()+""+filename);
}

}

publicstaticvoidmain(String[]args)throwsException
...{
newBusinessService().test();
sessionFactory.close();
}
}

Bag 允许重复 不能排序

属性:

name 指定集合的属性名

table 对应的 表

lazy 延迟检索策略

//inverese 有较好的update性能 但是不会按照one方来同步更新数据库(要注意)
order-by 数据库排序方式

元素:
<collection-id name="" table="" lazy="">
<generator class="native"/>
<collection-id/>

<key> 定义外键

//<one-to-many> 定义many 方的类

<element column="***" type="string" not-null="true"/>

注： 由于采用了延时检索策略 所以在读取的时候
用hibernate.isInitialized(Object)检查
用hibernate.initialize(java.lang.Object proxy) 来初始化集合

< idbag name ="images" table ="IMAGES" lazy ="true" >
< collection-id type ="long" column ="ID" >
< generator class ="native" />
</ collection-id >
< key column ="CUSTOMER_ID" />
< element column ="FILENAME" type ="string" not-null ="true" />

</ idbag >

例子
Customer.hbm.xml

<! DOCTYPEhibernate-mappingPUBLIC
"-//Hibernate/HibernateMappingDTD3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >

< hibernate-mapping >

< class name ="ergal.Customer" table ="CUSTOMERS" lazy ="true" >
< id name ="id" type ="long" column ="ID" >
< generator class ="native" />
</ id >

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

< property name ="age" column ="AGE" type ="int" />


< idbag name ="images" table ="IMAGES" lazy ="true" >
< collection-id type ="long" column ="ID" >
< generator class ="increment" />
</ collection-id >
< key column ="CUSTOMER_ID" />
< element column ="FILENAME" type ="string" not-null ="true" />
</ idbag >

</ class >

</ hibernate-mapping >

注：这里的collection-id 为increment 才能正常运行
运行hbm2ddl后产生两表
customers
1 - ID
2 - NAME
3 - AGE

IMAGES
1 - CUSTOMER_ID
2 - FILENAME
3 - ID

测试代码中
原来的
Set images=new HashSet();
改成
List images=new ArrayList();

也可以用java.util.Collection来代替List

注意：

虽然可以用List但是只要是idbag 集合中的元素就不会按照索引来排序
要排序用List映射

映射List 允许存放重复元素 可以按照索引排序

属性:

name 指定集合的属性名

table 对应的 表

lazy 延迟检索策略

inverese 有较好的update性能 但是不会按照one方来同步更新数据库(要注意)

元素:

<key column=""> 定义外键
<index column=""> 设置代表索引的字段
//<one-to-many> 定义many 方的类

<element column="***" type="string" not-null="true"/>

注： 由于采用了延时检索策略 所以在读取的时候
用hibernate.isInitialized(Object)检查
用hibernate.initialize(java.lang.Object proxy) 来初始化集合

< list name ="images" table ="IMAGES" lazy ="true" >
< key column ="CUSTOMER_ID" />
< index column ="POSTION" />
< element column ="FILENAME" type ="string" not-null ="true" />
</ list >

例子
Customer.hbm.xml

<? xmlversion="1.0" ?>
<! DOCTYPEhibernate-mappingPUBLIC
"-//Hibernate/HibernateMappingDTD3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >

< hibernate-mapping >

< class name ="ergal.Customer" table ="CUSTOMERS" lazy ="true" >
< id name ="id" type ="long" column ="ID" >
< generator class ="native" />
</ id >

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

< property name ="age" column ="AGE" type ="int" />


< list name ="images" table ="IMAGES" lazy ="true" >
< key column ="CUSTOMER_ID" />
< index column ="POSTION" />
< element column ="FILENAME" type ="string" not-null ="true" />
</ list >

</ class >

</ hibernate-mapping >

测试代码

Listimages = new ArrayList();
images.add( " image1.jpg " );
images.add( " image4.jpg " );
images.add( " image2.jpg " );
images.add( " image2.jpg " );
images.add( " image5.jpg " );

Customercustomer = new Customer( " Tom " , 21 ,images);
saveCustomer(customer);

Customerc = loadCustomer( new Long( 1 ));
System.out.println(customer.getImages().getClass().getName());

Listit = customer.getImages();

for ( int i = 0 ;i <= it.size() - 1 ;i ++ )
... {
StringfileName=(String)it.get(i);
System.out.println(customer.getName()+""+fileName);
}

注意： 取得元素的方法是String fileName=(String)it.get(i);

显然这种方法是可以为索引排序的

map 每个元素包含一对键对象和值对象 不会对键对象排序

属性:

name 指定集合的属性名

table 对应的 表

lazy 延迟检索策略

//inverese 有较好的update性能 但是不会按照one方来同步更新数据库(要注意)
order-by 数据库排序方式
sort 内存排序方式
元素:

<key column=""> 定义外键
<index column="" type=""> 设置代表和键对象对应的字段
//<one-to-many> 定义many 方的类

<element column="***" type="string" not-null="true"/>

注： 由于采用了延时检索策略 所以在读取的时候
用hibernate.isInitialized(Object)检查
用hibernate.initialize(java.lang.Object proxy) 来初始化集合

< map name ="images" table ="IMAGES" lazy ="true" >
< key column ="CUSTOMER_ID" />
< index column ="IMAGE_NAME" type ="string" />
< element column ="FILENAME" type ="string" not-null ="true" />
</ map >

例子
Customer.hbm.xml

<? xmlversion="1.0" ?>
<! DOCTYPEhibernate-mappingPUBLIC
"-//Hibernate/HibernateMappingDTD3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >

< hibernate-mapping >

< class name ="ergal.Customer" table ="CUSTOMERS" lazy ="true" >
< id name ="id" type ="long" column ="ID" >
< generator class ="native" />
</ id >

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

< property name ="age" column ="AGE" type ="int" />


< map name ="images" table ="IMAGES" lazy ="true" >
< key column ="CUSTOMER_ID" />
< index column ="IMAGE_NAME" type ="string" />
< element column ="FILENAME" type ="string" not-null ="true" />
</ map >

</ class >

</ hibernate-mapping >

运行hbm2ddl后产生两表
customers
1 - ID
2 - NAME
3 - AGE

IMAGES
1 - CUSTOMER_ID
2 - FILENAME
3 - IMAGE_NAME

测试代码 变成

Mapimages = new HashMap();
images.put( " image1 " , " image1.jpg " );
images.put( " image4 " , " image4.jpg " );
images.put( " image2 " , " image2.jpg " );
images.put( " imageTwo " , " image2.jpg " );
images.put( " image5 " , " image5.jpg " );

Customercustomer = new Customer( " Tom " , 21 ,images);
saveCustomer(customer);

Customerc = loadCustomer( new Long( 1 ));
System.out.println(customer.getImages().getClass().getName());

Mapim = customer.getImages();
Setkeys = im.keySet();
Iteratorit = keys.iterator();
while (it.hasNext())
... {
Stringkeyname=(String)it.next();
StringfileName=(String)im.get(keyname);
System.out.println(customer.getName()+""+keyname+""+fileName);
}

用了Map里的get(Object key) 和 keySet()方法
此方法不会对键对象排序

对集合排序

有两种方式：
在数据库中排序 order-by
在内存中排序 sort 体现在代码中 原来的Set 变成了SortedSet 查询时可以用TreeSet

<set>和<map>两种都支持
<idbag>支持 在内存中排序 sort
<list>两种都不支持
sort 在内存中排序
1 set
例子
Customer.hbm.xml

<? xmlversion="1.0" ?>
<! DOCTYPEhibernate-mappingPUBLIC
"-//Hibernate/HibernateMappingDTD3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >

< hibernate-mapping >

< class name ="ergal.Customer" table ="CUSTOMERS" lazy ="true" >
< id name ="id" type ="long" column ="ID" >
< generator class ="native" />
</ id >

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

< property name ="age" column ="AGE" type ="int" />


< set name ="images" table ="IMAGES"
inverse ="false"
cascade ="save-update"
lazy ="true"
sort ="natural" >
< key column ="CUSTOMER_ID" />
< element column ="FILENAME" type ="string" not-null ="true" />
</ set >

</ class >

</ hibernate-mapping >

Customer.java

package ergal;
// Generated2006-8-305:27:45byHibernateTools3.2.0.beta7


import java.util. * ;

/***/ /**
*Customergeneratedbyhbm2java
*/
public class Customer implements java.io.Serializable ... {

//Fields

privatelongid;
privateStringname;
privateintage;
privateSetimages=newTreeSet();

//Constructors

/***//**defaultconstructor*/
publicCustomer()...{
}

/***//**fullconstructor*/
publicCustomer(Stringname,intage,Setimages)...{
this.name=name;
this.age=age;
this.images=images;
}

//Propertyaccessors
publiclonggetId()...{
returnthis.id;
}

publicvoidsetId(longid)...{
this.id=id;
}
publicStringgetName()...{
returnthis.name;
}

publicvoidsetName(Stringname)...{
this.name=name;
}
publicintgetAge()...{
returnthis.age;
}

publicvoidsetAge(intage)...{
this.age=age;
}
publicSetgetImages()...{
returnthis.images;
}

publicvoidsetImages(Setimages)...{
this.images=images;
}


}

测试代码

Setimages = new TreeSet();
images.add( " image1.jpg " );
images.add( " image4.jpg " );
images.add( " image2.jpg " );
images.add( " image5.jpg " );

Customercustomer = new Customer( " Tom " , 21 ,images);
saveCustomer(customer);

Customerc = loadCustomer( new Long( 1 ));
System.out.println(customer.getImages().getClass().getName());

Iteratorit = customer.getImages().iterator();

while (it.hasNext())
... {
Stringfilename=(String)it.next();
System.out.println(customer.getName()+""+filename);
}

可以客户化 排序方式 要实现comparator接口

注意： 可能需要手动修改POJO
images集合必须是SortedSet类型

2 map

Customer.hbm.xml

<? xmlversion="1.0" ?>
<! DOCTYPEhibernate-mappingPUBLIC
"-//Hibernate/HibernateMappingDTD3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >

< hibernate-mapping >

< class name ="ergal.Customer" table ="CUSTOMERS" lazy ="true" >
< id name ="id" type ="long" column ="ID" >
< generator class ="native" />
</ id >

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

< property name ="age" column ="AGE" type ="int" />


< map name ="images" table ="IMAGES" lazy ="true" sort ="natural" >
< key column ="CUSTOMER_ID" />
< index column ="IMAGE_NAME" type ="string" />
< element column ="FILENAME" type ="string" not-null ="true" />
</ map >

</ class >

</ hibernate-mapping >

Customer.java

package ergal;
// Generated2006-8-306:00:11byHibernateTools3.2.0.beta7


import java.util. * ;

/***/ /**
*Customergeneratedbyhbm2java
*/
public class Customer implements java.io.Serializable ... {

//Fields

privatelongid;
privateStringname;
privateintage;
privateMapimages=newTreeMap();

//Constructors

/***//**defaultconstructor*/
publicCustomer()...{
}

/***//**fullconstructor*/
publicCustomer(Stringname,intage,Mapimages)...{
this.name=name;
this.age=age;
this.images=images;
}

//Propertyaccessors
publiclonggetId()...{
returnthis.id;
}

publicvoidsetId(longid)...{
this.id=id;
}
publicStringgetName()...{
returnthis.name;
}

publicvoidsetName(Stringname)...{
this.name=name;
}
publicintgetAge()...{
returnthis.age;
}

publicvoidsetAge(intage)...{
this.age=age;
}
publicMapgetImages()...{
returnthis.images;
}

publicvoidsetImages(Mapimages)...{
this.images=images;
}

}

注意： 可能需要手动修改POJO
images集合必须是SortedMap类型

order-by 在数据库中排序

只需在元素里加上 order-by属性
如

< set name ="images" table ="IMAGES"
inverse ="false"
cascade ="save-update"
lazy ="true"
order-by ="FILENAMEasc" >
< key column ="CUSTOMER_ID" />
< element column ="FILENAME" type ="string" not-null ="true" />
</ set >

也可以加上sql函数
如 order-by="lower(FILENAME) asc"

映射组件集合

组件也是一种值对象

它必须实现java.io.Serializable接口

它必须重新实现equals()和hashCode()方法, 始终和组合关键字在数据库中的概念保持一致

例子
Customer.hbm.xml

<? xmlversion="1.0" ?>
<! DOCTYPEhibernate-mappingPUBLIC
"-//Hibernate/HibernateMappingDTD3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >

< hibernate-mapping >

< class name ="ergal.Customer" table ="CUSTOMERS" lazy ="true" >
< id name ="id" type ="long" column ="ID" >
< generator class ="native" />
</ id >

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

< property name ="age" column ="AGE" type ="int" />


< set name ="images" table ="IMAGES" lazy ="true" order-by ="IMAGE_NAMEasc" >
< key column ="CUSTOMER_ID" />
< composite-element class ="ergal.Image" >
< parent name ="imageCustomer" />
< property name ="name" column ="IMAGE_NAME" type ="string" not-null ="true" />
< property name ="filename" column ="FILENAME" type ="string" not-null ="true" />
< property name ="sizeX" column ="SIZEX" type ="integer" not-null ="true" />
< property name ="sizeY" column ="SIZEY" type ="integer" not-null ="true" />
</ composite-element >
</ set >

</ class >

</ hibernate-mapping >

Image.java
需要手动添加 Customer 字段
parent不能用hbm2java来自动产生 不知道这是不是个Bug

package ergal;
// Generated2006-8-3020:35:11byHibernateTools3.2.0.beta7



/***/ /**
*Imagegeneratedbyhbm2java
*/
public class Image implements java.io.Serializable ... {

//Fields

privateStringname;
privateStringfilename;
privateIntegersizeX;
privateIntegersizeY;
privateCustomerimageCustomer;
//Constructors

/***//**defaultconstructor*/
publicImage()...{
}

/***//**fullconstructor*/
publicImage(Stringname,Stringfilename,IntegersizeX,IntegersizeY)...{
this.name=name;
this.filename=filename;
this.sizeX=sizeX;
this.sizeY=sizeY;
}

//Propertyaccessors
publicStringgetName()...{
returnthis.name;
}

publicvoidsetName(Stringname)...{
this.name=name;
}
publicStringgetFilename()...{
returnthis.filename;
}

publicvoidsetFilename(Stringfilename)...{
this.filename=filename;
}
publicIntegergetSizeX()...{
returnthis.sizeX;
}

publicvoidsetSizeX(IntegersizeX)...{
this.sizeX=sizeX;
}
publicIntegergetSizeY()...{
returnthis.sizeY;
}

publicvoidsetSizeY(IntegersizeY)...{
this.sizeY=sizeY;
}

publicCustomergetImageCustomer()
...{
returnthis.imageCustomer;
}

publicvoidsetImageCustomer(CustomerimageCustomer)
...{
this.imageCustomer=imageCustomer;
}

}

测试代码

Setimages = new HashSet();
images.add( new Image( " image1 " , " image1.jpg " , 50 , 50 ));
images.add( new Image( " image4 " , " image4.jpg " , 50 , 50 ));
images.add( new Image( " image2 " , " image2.jpg " , 50 , 50 ));
images.add( new Image( " image5 " , " image5.jpg " , 50 , 50 ));

Customercustomer = new Customer( " Tom " , 21 ,images);
saveCustomer(customer);

Customerc = loadCustomer( new Long( 1 ));
System.out.println(customer.getImages().getClass().getName());

Iteratorit = customer.getImages().iterator();


while (it.hasNext())
... {
Imageim=(Image)it.next();
System.out.println(c.getName()+""+im.getName()
+""+im.getFilename()+""+im.getSizeX()+""+im.getSizeY());
}