有兩個實Student和Course,他們之間的關(guān)系是多對多，在數(shù)據(jù)庫上，為了滿足3NF,會建立一個中間表Stu_Course來維護Student和Course之間的關(guān)系，在Hibernate中，則使用雙向多對多來體現(xiàn)這種結(jié)構(gòu)
數(shù)據(jù)庫腳本
?
create
?
table
?stu(id?
varchar
(
32
)?
primary
?
key
,name?
varchar
(
32
),cardid?
varchar
(
32
),age?
int
);
create
?
table
?course(id?
varchar
(
32
)?
primary
?
key
,name?
varchar
(
32
));
create
?
table
?stu_course(stu_id?
varchar
(
32
),course_id?
varchar
(
32
));
insert
?
into
?stu?
values
("
1
","tom","
200701
",
11
);
insert
?
into
?stu?
values
("
2
","tomclus","
200702
",
11
);
insert
?
into
?stu?
values
("
3
","spark","
200703
",
11
);
insert
?
into
?stu?
values
("
4
","jerry","
200704
",
11
);
insert
?
into
?course?
values
("
1
","history");
insert
?
into
?course?
values
("
2
","computer");
insert
?
into
?course?
values
("
3
","music");
insert
?
into
?course?
values
("
4
","encomic");
insert
?
into
?course?
values
("
5
","politics");
insert
?
into
?stu_course?
values
("
2
","
1
");
insert
?
into
?stu_course?
values
("
2
","
2
");
insert
?
into
?stu_course?
values
("
2
","
3
");
insert
?
into
?stu_course?
values
("
1
","
3
");
insert
?
into
?stu_course?
values
("
1
","
4
");
insert
?
into
?stu_course?
values
("
3
","
2
");
insert
?
into
?stu_course?
values
("
3
","
3
");
?POJO:
?
package
?Relation.ManytoMany;
import
?java.util.Set;
public
?
class
?Stu?
{
??
private
?String?id;
??
private
?String?cardid;
??
private
?String?name;
??
private
?
int
?age;
??
private
?Set?course;
public
?Set?getCourse()?
{
????
return
?course;
}
public
?
void
?setCourse(Set?course)?
{
????
this
.course?
=
?course;
}
public
?String?getId()?
{
????
return
?id;
}
public
?
void
?setId(String?id)?
{
????
this
.id?
=
?id;
}
public
?String?getCardid()?
{
????
return
?cardid;
}
public
?
void
?setCardid(String?cardid)?
{
????
this
.cardid?
=
?cardid;
}
public
?String?getName()?
{
????
return
?name;
}
public
?
void
?setName(String?name)?
{
????
this
.name?
=
?name;
}
public
?
int
?getAge()?
{
????
return
?age;
}
public
?
void
?setAge(
int
?age)?
{
????
this
.age?
=
?age;
}
}
package
?Relation.ManytoMany;
import
?java.util.HashSet;
import
?java.util.Set;
public
?
class
?Course?
{
???
private
?String?id;
???
private
?Set?students;
???
private
?String?name;
public
?String?getId()?
{
????
return
?id;
}
public
?
void
?setId(String?id)?
{
????
this
.id?
=
?id;
}
public
?Set?getStudents()?
{
????
return
?students;
}
public
?
void
?setStudents(Set?students)?
{
????
this
.students?
=
?students;
}
public
?String?getName()?
{
????
return
?name;
}
public
?
void
?setName(String?name)?
{
????
this
.name?
=
?name;
}
}
?
Hibernate.cfg.xml
?
<?
xml?version='1.0'?encoding='UTF-8'
?>
<!
DOCTYPE?hibernate-configuration?PUBLIC
??????????"-//Hibernate/Hibernate?Configuration?DTD?3.0//EN"
??????????"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"
>
<!--
?Generated?by?MyEclipse?Hibernate?Tools.???????????????????
-->
<
hibernate-configuration
>
<
session-factory
>
????
<
property?
name
="connection.username"
>
root
</
property
>
????
<
property?
name
="connection.url"
>
????????jdbc:mysql://localhost:3306/schoolproject?characterEncoding=gb2312
&
useUnicode=true
????
</
property
>
????
<
property?
name
="dialect"
>
????????org.hibernate.dialect.MySQLDialect
????
</
property
>
????
<
property?
name
="myeclipse.connection.profile"
>
mysql
</
property
>
????
<
property?
name
="connection.password"
>
1234
</
property
>
????
<
property?
name
="connection.driver_class"
>
????????com.mysql.jdbc.Driver
????
</
property
>
????
<
property?
name
="hibernate.dialect"
>
????????org.hibernate.dialect.MySQLDialect
????
</
property
>
????
<
property?
name
="hibernate.show_sql"
>
true
</
property
>
????
<
property?
name
="current_session_context_class"
>
thread
</
property
>
????
<
property?
name
="jdbc.batch_size"
>
15
</
property
>
????
<
mapping?
resource
="Relation/ManytoMany/Course.hbm.xml"
?
/>
????
<
mapping?
resource
="Relation/ManytoMany/Stu.hbm.xml"
?
/>
</
session-factory
>
</
hibernate-configuration
>
?
Stu.hbm.xml
?
<?
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?-?Hibernate?Tools
-->
<
hibernate-mapping
>
<
class?
name
="Relation.ManytoMany.Stu"
?table
="stu"
>
??
<
id?
name
="id"
?unsaved-value
="null"
>
????
<
generator?
class
="uuid.hex"
></
generator
>
??
</
id
>
??
<
property?
name
="cardid"
?type
="string"
/>
??
<
property?
name
="name"
?type
="string"
/>
??
<
property?
name
="age"
?type
="int"
/>
&nb
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