hibernate映射关系
hibernate映射关系
- 目录
- 说明
- 实体类User.java
- 实体类Department.java
- 实体类Course.java
- 配置文件User.hbm.xml
- 配置文件Department.hbm.xml
- 配置文件Course.hbm.xml
- 总结
目录
说明
一对多，多对多
- User.java和Course.java是多对多
- User.java和Department.java是多对一
实体类User.java
，代码片.
package com.entity.manytomany;
import java.util.Set;
public class User implements java.io.Serializable {
private Long usrId;
//一方的引用
private Department department;
private String usrName;
private String usrPassword;
private String usrDesc;
private String sex;
private Integer age;
//多方的集合
private Set<Course> courses;
public Long getUsrId() {
return usrId;
}
public void setUsrId(Long usrId) {
this.usrId = usrId;
}
public Department getDepartment() {
return department;
}
public void setDepartment(Department department) {
this.department = department;
}
public String getUsrName() {
return usrName;
}
public void setUsrName(String usrName) {
this.usrName = usrName;
}
public String getUsrPassword() {
return usrPassword;
}
public void setUsrPassword(String usrPassword) {
this.usrPassword = usrPassword;
}
public String getUsrDesc() {
return usrDesc;
}
public void setUsrDesc(String usrDesc) {
this.usrDesc = usrDesc;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public Set<Course> getCourses() {
return courses;
}
public void setCourses(Set<Course> courses) {
this.courses = courses;
}
}
实体类Department.java
，代码片.
package com.entity.manytomany;
import java.util.Set;
public class Department implements java.io.Serializable {
// Fields
private Integer depId;
private String depName;
//多方的集合
private Set<User> users;
public Integer getDepId() {
return depId;
}
public void setDepId(Integer depId) {
this.depId = depId;
}
public String getDepName() {
return depName;
}
public void setDepName(String depName) {
this.depName = depName;
}
public Set<User> getUsers() {
return users;
}
public void setUsers(Set<User> users) {
this.users = users;
}
}
实体类Course.java
，代码片.
package com.entity.manytomany;
import java.util.Set;
public class Course implements java.io.Serializable {
private Integer id;
private String cname;
//多方的集合
private Set<User> users;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getCname() {
return cname;
}
public void setCname(String cname) {
this.cname = cname;
}
public Set<User> getUsers() {
return users;
}
public void setUsers(Set<User> users) {
this.users = users;
}
}
配置文件User.hbm.xml
，代码片.
<?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">
<hibernate-mapping>
<class name="com.entity.manytomany.User" table="user" catalog="testdb">
<!-- 组合主键一
<component name="组件名" class="组件类的全名">
<property name="属性名1" column="字段名1"/>
<property name="属性名2" column="字段名2"/>
<property name="属性名3" column="字段名3"/>
</component>
-->
<id name="usrId" type="java.lang.Long">
<column name="usrId" />
<generator class="identity" />
</id>
<!-- 多对一 -->
<many-to-one name="department" class="com.entity.manytomany.Department" >
<!-- 对方的主键名 -->
<column name="depId" not-null="true" />
</many-to-one>
<property name="usrName" type="java.lang.String">
<column name="usr_name" length="50" not-null="true" />
</property>
<property name="usrPassword" type="java.lang.String">
<column name="usr_password" length="50" not-null="true" />
</property>
<property name="usrDesc" type="java.lang.String">
<column name="usr_desc" length="50" not-null="true" />
</property>
<property name="sex" type="java.lang.String">
<column name="sex" length="2" />
</property>
<property name="age" type="java.lang.Integer">
<column name="age" />
</property>
<!-- 多对多 ，创建关系表 usr_course-->
<set name="courses" table="usr_course" catalog="testdb" >
<!-- 外键 -->
<key>
<column name="usrId" not-null="true" />
</key>
<!-- 多对多-->
<many-to-many entity-name="com.entity.manytomany.Course">
<!-- Course的外键 （可以重命名，courseid）-->
<column name="courseid" not-null="true" />
</many-to-many>
</set>
</class>
</hibernate-mapping>
配置文件Department.hbm.xml
，代码片.
<?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">
<hibernate-mapping>
<class name="com.entity.manytomany.Department" table="department" catalog="testdb">
<id name="depId" type="java.lang.Integer">
<column name="depId" />
<generator class="identity" />
</id>
<property name="depName" type="java.lang.String">
<column name="depName" length="45" not-null="true" />
</property>
<!-- 一对多 ，让出控制权：inverse="true" -->
<set name="users" inverse="true" >
<!-- 主键名 -->
<key column="depId" not-null="true" />
<one-to-many class="com.entity.manytomany.User" />
</set>
</class>
</hibernate-mapping>
配置文件Course.hbm.xml
，代码片.
<?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">
<hibernate-mapping>
<class name="com.entity.manytomany.Course" table="course" catalog="testdb">
<id name="id" type="java.lang.Integer">
<column name="courseid" />
<generator class="native"></generator>
</id>
<property name="cname" type="java.lang.String">
<column name="cname" length="45" not-null="true" />
</property>
<!-- 多对多 ，创建关系表 usr_course，inverse="true"：控制器让给对方表-->
<set name="users" inverse="true" table="usr_course" catalog="testdb">
<!-- 外键 -->
<key>
<column name="courseid" not-null="true" />
</key>
<!-- 多对多-->
<many-to-many entity-name="com.entity.manytomany.User">
<!-- User的外键 -->
<column name="usrid" not-null="true" />
</many-to-many>
</set>
</class>
</hibernate-mapping>
总结
1. 在一中定义多方引用: Object.
2. 在多方定义一方的集: 合Set < >.
3. 一方交出控制权:< set inverse="true" >.
**引用包是最大的困难（一步一步来）**