Hibernate one-to-many && many-to-many 的关系映射

one-to-many 关系映射

实体类：

/**
* 订单的实体:
*
*/
public class Order {
private Integer oid;
private String addr;
// 订单属于某一个客户.放置一个客户的对象.
private Customer customer;
public Integer getOid() {
return oid;
}
public void setOid(Integer oid) {
this.oid = oid;
}
public String getAddr() {
return addr;
}
public void setAddr(String addr) {
this.addr = addr;
}
public Customer getCustomer() {
return customer;
}
public void setCustomer(Customer customer) {
this.customer = customer;
}

}

/**
* 客户的实体:
*
*/
public class Customer {
private Integer cid;
private String cname;
// 一个客户有多个订单.
private Set<Order> orders = new HashSet<Order>();
public Integer getCid() {
return cid;
}
public void setCid(Integer cid) {
this.cid = cid;
}
public String getCname() {
return cname;
}
public void setCname(String cname) {
this.cname = cname;
}
public Set<Order> getOrders() {
return orders;
}
public void setOrders(Set<Order> orders) {
this.orders = orders;
}

}

Order.hbm.xml配置

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="cn.itcast.hibernate3.demo2.Order" table="orders">
<!-- 配置唯一标识  -->
<id name="oid" column="oid">
<generator class="native"/>
</id>
<!-- 配置普通属性 -->
<property name="addr" column="addr" length="50"/>
<!-- 配置映射 -->
<!--
<many-to-one>标签
name    :关联对象的属性的名称.
column  :表中的外键名称.
class   :关联对象类的全路径
-->
<many-to-one name="customer" column="cno" class="cn.itcast.hibernate3.demo2.Customer"/>
</class>
</hibernate-mapping>

Customer.hbm.xml配置

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="cn.itcast.hibernate3.demo2.Customer" table="customer">
<!-- 配置唯一标识 -->
<id name="cid" column="cid">
<generator class="native"/>
</id>
<!-- 配置普通属性 -->
<property name="cname" column="cname" length="20"/>

<!-- 建立映射 -->
<!-- 配置一个集合 <set>的name Customer对象中的关联对象的属性名称. -->
<set name="orders" cascade="save-update" inverse="true">
<!-- <key>标签中column:用来描述一对多多的一方的外键的名称. -->
<key column="cno"></key>
<!-- 配置一个<one-to-many>标签中class属性:订单的类的全路径 -->
<one-to-many class="cn.itcast.hibernate3.demo2.Order"/>
</set>
</class>
</hibernate-mapping>

many-to-many 关系映射

实体类：

/**
* 学生的实体类
*
*/
public class Student {
private Integer sid;
private String sname;
// 一个学生选择多门课程:
private Set<Course> courses = new HashSet<Course>();
public Integer getSid() {
return sid;
}
public void setSid(Integer sid) {
this.sid = sid;
}
public String getSname() {
return sname;
}
public void setSname(String sname) {
this.sname = sname;
}
public Set<Course> getCourses() {
return courses;
}
public void setCourses(Set<Course> courses) {
this.courses = courses;
}

}

/**
* 课程的实体类:
*
*/
public class Course {
private Integer cid;
private String cname;
// 一个课程被多个学生选择:
private Set<Student> students = new HashSet<Student>();
public Integer getCid() {
return cid;
}
public void setCid(Integer cid) {
this.cid = cid;
}
public String getCname() {
return cname;
}
public void setCname(String cname) {
this.cname = cname;
}
public Set<Student> getStudents() {
return students;
}
public void setStudents(Set<Student> students) {
this.students = students;
}

}

Student.hbm.xml配置

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="cn.itcast.hibernate3.demo3.Student" table="student">
<!-- 配置唯一标识 -->
<id name="sid" column="sid">
<generator class="native"/>
</id>
<!-- 配置普通属性 -->
<property name="sname" column="sname" length="20"/>

<!-- 配置关联映射 -->
<!-- <set>标签 name:对应学生中的课程集合的名称   table:中间表名称. -->
<set name="courses" table="stu_cour" cascade="save-update,delete">
<!-- <key>中column写当前类在中间表的外键.-->
<key column="sno"></key>
<!-- <many-to-many>中class:另一方类的全路径. column:另一方在中间表中外键名称-->
<many-to-many class="cn.itcast.hibernate3.demo3.Course" column="cno"/>
</set>
</class>
</hibernate-mapping>

Course.hbm.xml配置

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="cn.itcast.hibernate3.demo3.Course" table="course">
<!-- 配置唯一标识 -->
<id name="cid" column="cid">
<generator class="native"/>
</id>
<!-- 配置普通属性 -->
<property name="cname" column="cname" length="20"/>
<!-- 配置与学生关联映射 -->
<!-- <set>中name:对应当前类中的学生的集合的名称  table:中间表的名称-->
<set name="students" table="stu_cour" inverse="true">
<!-- <key>中column:当前类在中间表中外键 -->
<key column="cno"></key>
<!-- <many-to-many>中class:另一方的类全路径. column:另一方在中间表中外键名称 -->
<many-to-many class="cn.itcast.hibernate3.demo3.Student" column="sno"/>
</set>
</class>
</hibernate-mapping>