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
<setname="images"table="IMAGES"
inverse="false"
cascade="save-update"
lazy="true">
<keycolumn="CUSTOMER_ID"/>
<elementcolumn="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>
<classname="ergal.Customer"table="CUSTOMERS"lazy="true">
<idname="id"type="long"column="ID">
<generatorclass="native"/>
</id>
<propertyname="name"column="NAME"type="string"/>
<propertyname="age"column="AGE"type="int"/>
<setname="images"table="IMAGES"
inverse="false"
cascade="save-update"
lazy="true">
<keycolumn="CUSTOMER_ID"/>
<elementcolumn="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
packageergal;
importjava.util.*;
importorg.hibernate.*;
importorg.hibernate.cfg.*;
importjava.sql.*;
publicclassBusinessService
...{
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
<idbagname="images"table="IMAGES"lazy="true">
<collection-idtype="long"column="ID">
<generatorclass="native"/>
</collection-id>
<keycolumn="CUSTOMER_ID"/>
<elementcolumn="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>
<classname="ergal.Customer"table="CUSTOMERS"lazy="true">
<idname="id"type="long"column="ID">
<generatorclass="native"/>
</id>
<propertyname="name"column="NAME"type="string"/>
<propertyname="age"column="AGE"type="int"/>
<idbagname="images"table="IMAGES"lazy="true">
<collection-idtype="long"column="ID">
<generatorclass="increment"/>
</collection-id>
<keycolumn="CUSTOMER_ID"/>
<elementcolumn="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
<listname="images"table="IMAGES"lazy="true">
<keycolumn="CUSTOMER_ID"/>
<indexcolumn="POSTION"/>
<elementcolumn="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>
<classname="ergal.Customer"table="CUSTOMERS"lazy="true">
<idname="id"type="long"column="ID">
<generatorclass="native"/>
</id>
<propertyname="name"column="NAME"type="string"/>
<propertyname="age"column="AGE"type="int"/>
<listname="images"table="IMAGES"lazy="true">
<keycolumn="CUSTOMER_ID"/>
<indexcolumn="POSTION"/>
<elementcolumn="FILENAME"type="string"not-null="true"/>
</list>
</class>
</hibernate-mapping>
测试代码
Listimages=newArrayList();
images.add("image1.jpg");
images.add("image4.jpg");
images.add("image2.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());
Listit=customer.getImages();
for(inti=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
<mapname="images"table="IMAGES"lazy="true">
<keycolumn="CUSTOMER_ID"/>
<indexcolumn="IMAGE_NAME"type="string"/>
<elementcolumn="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>
<classname="ergal.Customer"table="CUSTOMERS"lazy="true">
<idname="id"type="long"column="ID">
<generatorclass="native"/>
</id>
<propertyname="name"column="NAME"type="string"/>
<propertyname="age"column="AGE"type="int"/>
<mapname="images"table="IMAGES"lazy="true">
<keycolumn="CUSTOMER_ID"/>
<indexcolumn="IMAGE_NAME"type="string"/>
<elementcolumn="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=newHashMap();
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=newCustomer("Tom",21,images);
saveCustomer(customer);
Customerc=loadCustomer(newLong(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>
<classname="ergal.Customer"table="CUSTOMERS"lazy="true">
<idname="id"type="long"column="ID">
<generatorclass="native"/>
</id>
<propertyname="name"column="NAME"type="string"/>
<propertyname="age"column="AGE"type="int"/>
<setname="images"table="IMAGES"
inverse="false"
cascade="save-update"
lazy="true"
sort="natural">
<keycolumn="CUSTOMER_ID"/>
<elementcolumn="FILENAME"type="string"not-null="true"/>
</set>
</class>
</hibernate-mapping>
Customer.java
packageergal;
//Generated2006-8-305:27:45byHibernateTools3.2.0.beta7
importjava.util.*;
/***//**
*Customergeneratedbyhbm2java
*/
publicclassCustomerimplementsjava.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=newTreeSet();
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);
}
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>
<classname="ergal.Customer"table="CUSTOMERS"lazy="true">
<idname="id"type="long"column="ID">
<generatorclass="native"/>
</id>
<propertyname="name"column="NAME"type="string"/>
<propertyname="age"column="AGE"type="int"/>
<mapname="images"table="IMAGES"lazy="true"sort="natural">
<keycolumn="CUSTOMER_ID"/>
<indexcolumn="IMAGE_NAME"type="string"/>
<elementcolumn="FILENAME"type="string"not-null="true"/>
</map>
</class>
</hibernate-mapping>
Customer.java
packageergal;
//Generated2006-8-306:00:11byHibernateTools3.2.0.beta7
importjava.util.*;
/***//**
*Customergeneratedbyhbm2java
*/
publicclassCustomerimplementsjava.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
<setname="images"table="IMAGES"
inverse="false"
cascade="save-update"
lazy="true"
order-by="FILENAMEasc">
<keycolumn="CUSTOMER_ID"/>
<elementcolumn="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>
<classname="ergal.Customer"table="CUSTOMERS"lazy="true">
<idname="id"type="long"column="ID">
<generatorclass="native"/>
</id>
<propertyname="name"column="NAME"type="string"/>
<propertyname="age"column="AGE"type="int"/>
<setname="images"table="IMAGES"lazy="true"order-by="IMAGE_NAMEasc">
<keycolumn="CUSTOMER_ID"/>
<composite-elementclass="ergal.Image">
<parentname="imageCustomer"/>
<propertyname="name"column="IMAGE_NAME"type="string"not-null="true"/>
<propertyname="filename"column="FILENAME"type="string"not-null="true"/>
<propertyname="sizeX"column="SIZEX"type="integer"not-null="true"/>
<propertyname="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
packageergal;
//Generated2006-8-3020:35:11byHibernateTools3.2.0.beta7
/***//**
*Imagegeneratedbyhbm2java
*/
publicclassImageimplementsjava.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=newHashSet();
images.add(newImage("image1","image1.jpg",50,50));
images.add(newImage("image4","image4.jpg",50,50));
images.add(newImage("image2","image2.jpg",50,50));
images.add(newImage("image5","image5.jpg",50,50));
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())
...{
Imageim=(Image)it.next();
System.out.println(c.getName()+""+im.getName()
+""+im.getFilename()+""+im.getSizeX()+""+im.getSizeY());
}
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