OA项目8:表映射关系及跟对象之间的关系处理

首注：本学习教程为传智播客汤阳光讲师所公布的免费OA项目视频我的文字版实践笔记，本人用此来加强巩固自己开发知识，如有网友转载，请注明。谢谢。

一　之前我们写了两个功能，这两个功能之间没有什么关联关系。下面我们做的用户管理功能将和之前的两个功能有相应的关联关系，所以要先匹配之间的关联关系，然后才能够进行代码的编写，下图就是三个功能类之间的模型图，这有益于外面分析功能间的关系和编写修改功能代码：

二　将上面三个实体类全部写出来，具体如下：

 1 package cn.clear.oa.domain;
 2 
 3 import java.util.HashSet;
 4 import java.util.Set;
 5 
 6 public class User {
 7     private Long id;
 8     private String name;
 9     private String loginName;
10     private String gender;
11     private String phoneNumber;
12     private String email;
13     private String password;
14     private String description;
15     private Department department;
16     private Set<Role> roles = new HashSet<Role>();
17     public Set<Role> getRoles() {
18         return roles;
19     }
20     public void setRoles(Set<Role> roles) {
21         this.roles = roles;
22     }
23     public Long getId() {
24         return id;
25     }
26     public void setId(Long id) {
27         this.id = id;
28     }
29     public String getName() {
30         return name;
31     }
32     public void setName(String name) {
33         this.name = name;
34     }
35     public String getLoginName() {
36         return loginName;
37     }
38     public void setLoginName(String loginName) {
39         this.loginName = loginName;
40     }
41     public String getGender() {
42         return gender;
43     }
44     public void setGender(String gender) {
45         this.gender = gender;
46     }
47     public String getPhoneNumber() {
48         return phoneNumber;
49     }
50     public void setPhoneNumber(String phoneNumber) {
51         this.phoneNumber = phoneNumber;
52     }
53     public String getEmail() {
54         return email;
55     }
56     public void setEmail(String email) {
57         this.email = email;
58     }
59     public String getPassword() {
60         return password;
61     }
62     public void setPassword(String password) {
63         this.password = password;
64     }
65     public String getDescription() {
66         return description;
67     }
68     public void setDescription(String description) {
69         this.description = description;
70     }
71     public Department getDepartment() {
72         return department;
73     }
74     public void setDepartment(Department department) {
75         this.department = department;
76     }
77     
78     
79 }

User.java

 1 package cn.clear.oa.domain;
 2 
 3 import java.util.HashSet;
 4 import java.util.Set;
 5 
 6 public class Role {
 7 
 8     private Long id;
 9     private String name;
10     private String description;
11     private Set<User> users = new HashSet<User>();
12     public Long getId() {
13         return id;
14     }
15     public void setId(Long id) {
16         this.id = id;
17     }
18     public String getName() {
19         return name;
20     }
21     public void setName(String name) {
22         this.name = name;
23     }
24     public String getDescription() {
25         return description;
26     }
27     public void setDescription(String description) {
28         this.description = description;
29     }
30     public Set<User> getUsers() {
31         return users;
32     }
33     public void setUsers(Set<User> users) {
34         this.users = users;
35     }
36     
37     
38 }

Role.java

 1 package cn.clear.oa.domain;
 2 
 3 import java.util.HashSet;
 4 import java.util.Set;
 5 
 6 public class Department {
 7 
 8     private Long id;
 9     private String name;
10     private String description;
11     private Department parent;
12     private Set<User> users = new HashSet<User>();
13     private Set<Department> children = new HashSet<Department>();
14     
15     public Department getParent() {
16         return parent;
17     }
18     public void setParent(Department parent) {
19         this.parent = parent;
20     }
21     public Set<User> getUsers() {
22         return users;
23     }
24     public void setUsers(Set<User> users) {
25         this.users = users;
26     }
27     public Set<Department> getChildren() {
28         return children;
29     }
30     public void setChildren(Set<Department> children) {
31         this.children = children;
32     }
33     public Long getId() {
34         return id;
35     }
36     public void setId(Long id) {
37         this.id = id;
38     }
39     public String getName() {
40         return name;
41     }
42     public void setName(String name) {
43         this.name = name;
44     }
45     public String getDescription() {
46         return description;
47     }
48     public void setDescription(String description) {
49         this.description = description;
50     }
51     
52     
53 }

Department.java

三　分析三个类的关联关系，在映射文件中配置相应的属性，我将映射文件内容表于下面：

 1 <?xml version="1.0"?>
 2 <!DOCTYPE hibernate-mapping PUBLIC 
 3     "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 4     "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
 5 
 6 <hibernate-mapping package="cn.clear.oa.domain">
 7     <class name="User" table="oa_user">
 8         <id name="id"><generator class="native"/></id>
 9         <property name="name"/>
10         <property name="loginName"/>
11         <property name="gender"/>
12         <property name="phoneNumber"/>
13         <property name="email"/>
14         <property name="password"/>
15         <property name="description"/>
16         <!-- department属性，本类与Department的多对1关系 -->
17         <many-to-one name="department" class="Department" column="departmentId"></many-to-one>
18         <!-- roles属性，本类与Role的多对多关系 -->
19         <set name="roles" table="oa_user_role">
20             <key column="userId"></key>
21             <many-to-many class="Role" column="roleId"></many-to-many>
22         </set>
23     </class>
24 </hibernate-mapping>

User.hbm.xml

 1 <?xml version="1.0"?>
 2 <!DOCTYPE hibernate-mapping PUBLIC 
 3     "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 4     "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
 5 
 6 <hibernate-mapping package="cn.clear.oa.domain">
 7     <class name="Role" table="oa_role">
 8         <id name="id">
 9             <generator class="native" />
10         </id>
11         <property name="name" />
12         <property name="description" />
13         <!-- users属性，本类与User的多对多 -->
14         <set name="users" table="oa_user_role">
15             <key column="roleId"></key>
16             <many-to-many class="User" column="userId"></many-to-many>
17         </set> 
18     </class>
19 </hibernate-mapping>

Role.hbm.xml

 1 <?xml version="1.0"?>
 2 <!DOCTYPE hibernate-mapping PUBLIC 
 3     "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 4     "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
 5 
 6 <hibernate-mapping package="cn.clear.oa.domain">
 7     <class name="Department" table="oa_department">
 8         <id name="id"><generator class="native"/></id>
 9         <property name="name"/>
10         <property name="description"/>
11         <!-- users属性，本类与User的1对多 -->
12         <set name="users">
13             <key column="departmentId"></key>
14             <one-to-many class="User"/>
15         </set>
16         <!-- parent属性，本类与（上级）Department的多对1 -->
17         <many-to-one name="parent" class="Department" column="parentId"></many-to-one>
18         <!-- children属性，本类与（下级）Department的1对多 -->
19         <set name="children">
20             <key column="parentId"></key>
21             <one-to-many class="Department"/>
22         </set>
23     </class>
24 </hibernate-mapping>

Department.hbm.xml

　　总结出映射文件的写法，下面的内容就来概括：

例：

　　格式：a属性，本类与b的c。

　　解释：a为属性名，b为关联的对象名，c为对应的关系。

　　模板（以后在填写多表映射时可以以以此为模板）：

　　　　1）多对一：

　　　　　　<many-to-one name="a" class="b" column="a+Id"></many-to-one>

　　　　2）一对多：

　　　　　　　　<one-to-many class="b"/>

　　　　　　</set>

　　　　3）多对多：

　　　　　　　　<many-to-many class="b" column="b类名+Id"></many-to-many>

　　　　　　</set>

四　以上做完后启动之前的测试类TestSpring.java中的测试SessionFactory的方法进行自动建表，如不报错，去数据库看看是否正确。

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原文地址：https://www.cnblogs.com/clear5/p/4043233.html