mybatis的映射文件写法多种多样，不同的写法和用法，在实际开发过程中所消耗的开发时间、维护时间有很大差别，今天我就把我认为比较简单的一种映射文件写法记录下来，供大家修改建议，争取找到一个最优写法~~:
以User对象和UserMap.xml为例讲解，代码如下：
User为用户实体类(仅作为讲解，可以只关注引用类型变量，get/set方法省略)：
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
|
import com.google.common.collect.Lists;import com.gukeer.common.persistence.DataEntity;import com.gukeer.modules.personal.entity.Dept;import com.gukeer.modules.personal.entity.Staff;import com.gukeer.modules.school.entity.School;import java.util.Date;/*** 用户Entity** auther:cc* date:2016/9/2*/public class User extends DataEntity<User> {private static final long serialVersionUID = 1L;private String id;private Office company; // 归属公司private Office office; // 归属部门private String loginName;// 登录名private String password;// 密码private String no; // 工号private String name; // 姓名private String email; // 邮箱private String phone; // 电话private String mobile; // 手机private String userType;// 用户类型private String loginIp; // 最后登陆IPprivate Date loginDate; // 最后登陆日期private String loginFlag; // 是否允许登陆private String qrCode; // 二维码private String oldLoginName;// 原登录名private String newPassword; // 新密码private String oldLoginIp; // 上次登陆IPprivate Date oldLoginDate; // 上次登陆日期private Dept dept; //部门private Staff staff; //职位private Role role; // 根据角色查询用户条件private List<Role> roleList = Lists.newArrayList(); // 拥有角色列表private School school; //归属学校private String remarks; // 备注private User createBy; // 创建者private Date createDate; // 创建日期private User updateBy; // 更新者private Date updateDate; // 更新日期private String delFlag; // 删除标记（0：正常；1：删除；2：审核）} |
针对引用类型的成员变量，为了可以在查询过程中直接赋值，在映射文件中可以直接将查询结果赋值给返回的结果集：
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
|
<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="com.gk.modules.sys.dao.UserDao"> <!-- 重点就是这一段，将数据库保存的id字段直接赋值给一个对象的成员变量中，比如a.company_id AS "company.id"，此时后台查询回的List或User对象中的属性可以直接通过user.getCompany().getId()来获取到--> <!-- 当然Company中的引用类型变量也可以使用这种方法来赋值，通过LEFT JOIN可以联查多表，这是数据库查询方面的操作，这里不作讨论 --><sql id="userColumns">a.id,a.company_id AS "company.id",a.office_id AS "office.id",a.login_name,a.password,a.no,a.name,a.email,a.phone,a.mobile,a.user_type,a.login_ip,a.login_date,a.remarks,a.login_flag,a.photo,a.qrcode,a.create_by AS "createBy.id",a.create_date,a.update_by AS "updateBy.id",a.update_date,a.del_flag,c.name AS "company.name",c.parent_id AS "company.parent.id",c.parent_ids AS "company.parentIds",ca.id AS "company.area.id",ca.name AS "company.area.name",ca.parent_id AS "company.area.parent.id",ca.parent_ids AS "company.area.parentIds",o.name AS "office.name",o.parent_id AS "office.parent.id",o.parent_ids AS "office.parentIds",oa.id AS "office.area.id",oa.name AS "office.area.name",oa.parent_id AS "office.area.parent.id",oa.parent_ids AS "office.area.parentIds",cu.id AS "company.primaryPerson.id",cu.name AS "company.primaryPerson.name",cu2.id AS "company.deputyPerson.id",cu2.name AS "company.deputyPerson.name",ou.id AS "office.primaryPerson.id",ou.name AS "office.primaryPerson.name",ou2.id AS "office.deputyPerson.id",ou2.name AS "office.deputyPerson.name",sc.xxlx AS "school.xxlx",sc.xxmc AS "school.xxmc"</sql><sql id="userJoins">LEFT JOIN sys_office c ON c.id = a.company_idLEFT JOIN sys_area ca ON ca.id = c.area_idLEFT JOIN sys_office o ON o.id = a.office_idLEFT JOIN sys_area oa ON oa.id = o.area_idLEFT JOIN sys_user cu ON cu.id = c.primary_personLEFT JOIN sys_user cu2 ON cu2.id = c.deputy_personLEFT JOIN sys_user ou ON ou.id = o.primary_personLEFT JOIN sys_user ou2 ON ou2.id = o.deputy_personLEFT JOIN xj_school sc ON sc.id = a.school</sql><!-- 查询语句，根据Id查询结果，返回类型可以直接写User，而不同配置resultMap省略编写xml的时间 --><select id="getUserById" resultType="User">SELECT<include refid="userColumns"/>FROM sys_user a<include refid="userJoins"/>WHERE a.id = #{id}</select><!-- 查询语句，根据User对象来查询，这里的参数即为User变量 --><select id="getByLoginName" resultType="User" parameterType="User">SELECT<include refid="userColumns"/>FROM sys_user a<include refid="userJoins"/>WHERE a.login_name = #{loginName} AND a.del_flag = #{DEL_FLAG_NORMAL}</select><!-- 插入语句，参数肯定是User对象 --><insert id="insert">INSERT INTO sys_user(id, company_id, office_id, login_name, password, no, name, email, phone, mobile, user_type, create_by, create_date, update_by, update_date, remarks, login_flag, photo, qrcode,del_flag,dept_id,staff_id,school) VALUES (#{id}, #{company.id}, #{office.id}, #{loginName}, #{password}, #{no}, #{name}, #{email}, #{phone}, #{mobile}, #{userType}, #{createBy.id}, #{createDate}, #{updateBy.id}, #{updateDate}, #{remarks}, #{loginFlag}, #{photo}, #{qrCode},#{delFlag},#{dept.id},#{staff.id},#{school.id})</insert><!-- 更新语句，参数也是User对象 --><update id="update">UPDATE sys_user SET company_id = #{company.id}, office_id = #{office.id}, login_name = #{loginName}, password = #{password}, no = #{no}, name = #{name}, email = #{email}, phone = #{phone}, mobile = #{mobile}, user_type = #{userType}, update_by = #{updateBy.id}, update_date = #{updateDate}, remarks = #{remarks},login_flag = #{loginFlag},photo = #{photo},qrcode = #{qrCode},school = #{school.id}WHERE id = #{id}</update><!-- 物理删除用户 --><update id="delete">DELETE FROM sys_user WHERE id = #{id}</update><!-- 逻辑删除用户 --><update id="deleteByLogic">UPDATE sys_user SET del_flag = #{DEL_FLAG_DELETE}WHERE id = #{id}</update></mapper> |
原文链接：http://www.cnblogs.com/spiders/archive/2016/09/02/5835955.html
