設置Mybatis（3.2.8）實體嵌套關係（一對多，多對多）遇到的問題及經驗總結記錄
原始目標：
配置好mapper,使得能夠在實體中表示表之間的聯繫(一個表外鍵，用另外一個實體表示）
深讀了mybatis 官方的文章，最後總結出一最重要的的一條，必定要好好利用官方 的autoMapping 特性，不然就得一條條寫映射關係了。固然對於實體的嵌套填充， 我只作一層，再往下走就須要在程序邏輯上作一些處理 html
這裏配置的邏輯只與表在邏輯上的鏈接相關，是否在數據中實現關係無關。 java
1、犯過的錯誤
一開始我把全部相關的表的列都放進來，致使有錯誤不能排除，因此搞了一天加一夜。後面我只要了幾個關鍵的，這樣語句有錯誤也好調試
2、正確的認識
1.
爲了有效利用automaping 特性，在取別名時除前綴外，後面的名稱咱們將採起與實體屬性同樣的名稱，這樣，咱們在resultmap中就無需再一一對上屬性
2.
<resultMap id="psProjectPushResultMap" type="com.thinkgem.jeesite.modules.projectschedule.entity.PsProjectPush" autoMapping ="true">
<id property="id"
column="id"/>
</resultMap>
這裏的column咱們只須要考慮不包括前綴的
3.映射方式主要有兩種
第一種：直接取別名，用resultType返回結果，這種方式只能針對簡單的，且沒有List<Entity>之類的 collection; 直接取名時，對於entity屬性別名通常取屬性.id(
a.customer_id as customer.id)，這樣mybatis會將這個值送給對像的ID字段.
第二種：用resultMap返回結果，當有List<Entity>這種Collection時必須用這一種方式，如下爲相關解釋
<association
property="customer" column="
customerid" resultMap="psCustomerResultMap" columnPrefix="customer_"/>
property 爲實體中的屬性值，customerid爲sql語句中的別名(通常是用一關聯另外一實體，在使用association這種方式下，這個別名保留與表格相同就好
4關於嵌套執行sql仍是一條SQL鏈接多表
嵌套執行：官方演示了此方式，也方便理解，但因爲效率太差不推薦
一條大SQL（JOIN)：此方式是官方 推薦方式，映射時官方 會自本身移除重複記錄，此也爲推薦方式。
5.關聯的主表字段取別名時不須要加前綴。
6.鏈接時注意鏈接方式，通常是以左鏈接爲主
- INNER JOIN: Returns all rows when there is at least one match in BOTH tables
- LEFT JOIN: Return all rows from the left table, and the matched rows from the right table
- RIGHT JOIN: Return all rows from the right table, and the matched rows from the left table
- FULL JOIN: Return all rows when there is a match in ONE of the tables
3、注意事項
官方舉例在別名時推薦使用的是下劃線，
1. 但在如下的別名方式下，.也是能夠的。
<sql id="psCustomerColumns">
c.id as "customer_id",
c.code as "customer_code",
c.name as "customer_name"
</sql>
2.此類別名方式下
<sql id="psProjectPushColumns">
push.id as "push.id",
push.projectid AS "push.project.id",
push.userid AS "push.user.id",
push.is_readed AS "push.isReaded"
</sql>
也是能夠的
若是下劃線之外方式不能正確工做，就改用官方的下劃線前綴。
3、其實應該注意的點
如今來看看這個mapper的映射配置如何編寫，注意示例中的如下幾點：
一、constructor 實體的構造方法
二、autoMapping 自動屬性映射
三、collection 集合屬性的映射
四、association 關聯屬性的映射 git
五、mapUnderscoreToCamelCase 是否開啓自動駝峯命名規則，全局配置. github
實例一，使用下劃線： sql
PsProjectDao.xml api
<?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.thinkgem.jeesite.modules.projectschedule.dao.PsProjectDao">
<!-- <typeAlias type="com.someapp.model.User" alias="User"/> -->
<!-- begin result map area -->
<resultMap id="psProjectResultMap" type="com.thinkgem.jeesite.modules.projectschedule.entity.PsProject" autoMapping ="true">
<id property="id" column="id" />
<!-- <result property="title" column="blog_title"/>-->
<association property="customer" column="customerid" resultMap="psCustomerResultMap" columnPrefix="customer_"/>
<association property="department" column="departmentid" resultMap="departmentResultMap" columnPrefix="department_"/>
<association property="projectManager" column="projectManagerid" resultMap="userResultMap" columnPrefix="projectManager_"/>
<association property="marketer" column="marketerid" resultMap="userResultMap" columnPrefix="marketer_"/>
<collection property="push" column="push" ofType="PsProjectPush" resultMap="psProjectPushResultMap" columnPrefix="push_"/>
</resultMap>
<resultMap id="userResultMap" type="com.thinkgem.jeesite.modules.sys.entity.User" autoMapping ="true">
<id property="id" column="id"/>
</resultMap>
<resultMap id="departmentResultMap" type="com.thinkgem.jeesite.modules.sys.entity.Office" autoMapping ="true" >
<id property="id" column="id"/>
</resultMap>
<resultMap id="psCustomerResultMap" type="com.thinkgem.jeesite.modules.projectschedule.entity.PsCustomer" autoMapping ="true">
<id property="id" column="id"/>
</resultMap>
<resultMap id="psProjectPushResultMap" type="com.thinkgem.jeesite.modules.projectschedule.entity.PsProjectPush" autoMapping ="true">
<id property="id" column="id"/>
</resultMap>
<!-- end resultmap area -->
<!-- begin sql columns area -->
<sql id="psProjectColumns">
a.id AS "id",
a.code AS "code",
a.name AS "name",
a.type AS "type",
a.importance_degree AS "importanceDegree",
a.tech_state AS "techState",
a.customerid AS "customerid",
a.departmentid AS "departmentid",
a.project_managerid AS "projectManagerid",
a.plan_starttime AS "planStarttime",
a.plan_endtime AS "planEndtime",
a.state AS "state",
a.act_starttime AS "actStarttime",
a.act_endtime AS "actEndtime",
a.sending_time AS "sendingTime",
a.old_plan_starttime AS "oldPlanStarttime",
a.old_plan_endtime AS "oldPlanEndtime",
a.delivery_time AS "deliveryTime",
a.complete_status AS "completeStatus",
a.marketerid AS "marketerid",
a.create_by AS "createBy.id",
a.create_date AS "createDate",
a.update_by AS "updateBy.id",
a.update_date AS "updateDate",
a.remarks AS "remarks",
a.del_flag AS "delFlag"
</sql>
<sql id="departmentColumns">
d.id as "department_id",
d.name as "department_name"
</sql>
<sql id="projectManagerColumns">
pm.id as "projectManager_id",
pm.name as "projectManager_name"
</sql>
<sql id="marketerColumns">
m.id as "marketer_id",
m.name as "marketer_name"
</sql>
<sql id="psCustomerColumns">
c.id as "customer_id",
c.code as "customer_code",
c.name as "customer_name"
</sql>
<sql id="psProjectPushColumns">
ps.id as "push_id",
ps.projectid AS "push_project.id",
ps.userid AS "push_user.id",
ps.is_readed AS "push_isReaded"
</sql>
<!-- end sql columns area -->
<sql id="psProjectJoins">
LEFT JOIN ps_customer c ON c.id = a.customerid
LEFT JOIN sys_office d ON d.id = a.departmentid
LEFT JOIN sys_user pm ON pm.id = a.project_managerid
LEFT JOIN sys_user m ON m.id = a.marketerid
LEFT JOIN ps_project_push ps ON ps.projectid=a.id
</sql>
<select id="findAllList" resultMap="psProjectResultMap">
SELECT
<include refid="psProjectColumns"/>,
<include refid="departmentColumns"/>,
<include refid="projectManagerColumns"/>,
<include refid="marketerColumns"/>,
<include refid="psCustomerColumns"/>,
<include refid="psProjectPushColumns"/>
FROM ps_project a
<include refid="psProjectJoins"/>
<where>
a.del_flag = #{DEL_FLAG_NORMAL}
</where>
<choose>
<when test="page !=null and page.orderBy != null and page.orderBy != ''">
ORDER BY ${page.orderBy}
</when>
<otherwise>
ORDER BY a.update_date DESC
</otherwise>
</choose>
</select>
<insert id="insert">
INSERT INTO ps_project(
id,
code,
name,
type,
importance_degree,
tech_state,
customerid,
departmentid,
managerid,
plan_starttime,
plan_endtime,
state,
act_starttime,
act_endtime,
sending_time,
old_plan_starttime,
old_plan_endtime,
delivery_time,
complete_status,
marketerid,
create_by,
create_date,
update_by,
update_date,
remarks,
del_flag
) VALUES (
#{id},
#{code},
#{name},
#{type},
#{importanceDegree},
#{techState},
#{customer.id},
#{department.id},
#{projectManager.id},
#{planStarttime},
#{planEndtime},
#{state},
#{actStarttime},
#{actEndtime},
#{sendingTime},
#{oldPlanStarttime},
#{oldPlanEndtime},
#{deliveryTime},
#{completeStatus},
#{marketer.id},
#{createBy.id},
#{createDate},
#{updateBy.id},
#{updateDate},
#{remarks},
#{delFlag}
)
</insert>
<update id="update">
UPDATE ps_project SET
code = #{code},
name = #{name},
type = #{type},
importance_degree = #{importanceDegree},
tech_state = #{techState},
customerid = #{customer.id},
departmentid = #{department.id},
managerid = #{projectManager.id},
plan_starttime = #{planStarttime},
plan_endtime = #{planEndtime},
state = #{state},
act_starttime = #{actStarttime},
act_endtime = #{actEndtime},
sending_time = #{sendingTime},
old_plan_starttime = #{oldPlanStarttime},
old_plan_endtime = #{oldPlanEndtime},
delivery_time = #{deliveryTime},
complete_status = #{completeStatus},
marketerid = #{marketer.id},
update_by = #{updateBy.id},
update_date = #{updateDate},
remarks = #{remarks}
WHERE id = #{id}
</update>
<update id="delete">
UPDATE ps_project SET
del_flag = #{DEL_FLAG_DELETE}
WHERE id = #{id}
</update>
</mapper>
<?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.thinkgem.jeesite.modules.projectschedule.dao.PsProjectDao">
<!-- <typeAlias type="com.someapp.model.User" alias="User"/> -->
<!-- begin result map area -->
<resultMap id="psProjectResultMap"
type="com.thinkgem.jeesite.modules.projectschedule.entity.PsProject"
autoMapping="true">
<id property="id" column="id" />
<!-- <result property="title" column="blog_title"/> -->
<association property="customer" column="customerid"
resultMap="psCustomerResultMap" columnPrefix="customer." />
<association property="department" column="departmentid"
resultMap="departmentResultMap" columnPrefix="department." />
<association property="projectManager" column="projectManagerid"
resultMap="userResultMap" columnPrefix="projectManager." />
<association property="marketer" column="marketerid"
resultMap="userResultMap" columnPrefix="marketer." />
<collection property="push" column="push" ofType="PsProjectPush"
resultMap="psProjectPushResultMap" columnPrefix="push." />
</resultMap>
<resultMap id="userResultMap" type="com.thinkgem.jeesite.modules.sys.entity.User"
autoMapping="true">
<id property="id" column="id" />
</resultMap>
<resultMap id="departmentResultMap"
type="com.thinkgem.jeesite.modules.sys.entity.Office" autoMapping="true">
<id property="id" column="id" />
</resultMap>
<resultMap id="psCustomerResultMap"
type="com.thinkgem.jeesite.modules.projectschedule.entity.PsCustomer"
autoMapping="true">
<id property="id" column="id" />
</resultMap>
<resultMap id="psProjectPushResultMap"
type="com.thinkgem.jeesite.modules.projectschedule.entity.PsProjectPush"
autoMapping="true">
<id property="id" column="id" />
</resultMap>
<!-- end resultmap area -->
<!-- begin sql columns area -->
<sql id="psProjectColumns">
a.id AS "id",
a.code AS "code",
a.name AS "name",
a.type AS
"type",
a.importance_degree AS "importanceDegree",
a.tech_state AS
"techState",
a.customerid AS "customerid",
a.departmentid AS
"departmentid",
a.project_managerid AS "projectManagerid",
a.plan_starttime AS "planStarttime",
a.plan_endtime AS "planEndtime",
a.state AS "state",
a.act_starttime AS "actStarttime",
a.act_endtime AS
"actEndtime",
a.sending_time AS "sendingTime",
a.old_plan_starttime AS
"oldPlanStarttime",
a.old_plan_endtime AS "oldPlanEndtime",
a.delivery_time AS "deliveryTime",
a.complete_status AS
"completeStatus",
a.marketerid AS "marketerid",
a.create_by AS
"createBy.id",
a.create_date AS "createDate.id",
a.update_by AS
"updateBy.id",
a.update_date AS "updateDate.id",
a.remarks AS "remarks",
a.del_flag AS "delFlag"
</sql>
<sql id="departmentColumns">
department.id as "department.id",
department.name as "department.name"
</sql>
<sql id="projectManagerColumns">
projectManager.id as "projectManager.id",
projectManager.name as "projectManager.name"
</sql>
<sql id="marketerColumns">
marketer.id as "marketer.id",
marketer.name as "marketer.name"
</sql>
<sql id="psCustomerColumns">
customer.id as "customer.id",
customer.code as
"customer.code",
customer.name as "customer.name"
</sql>
<sql id="psProjectPushColumns">
push.id as "push.id",
push.projectid AS "push.project.id",
push.userid AS "push.user.id",
push.is_readed AS "push.isReaded"
</sql>
<!-- end sql columns area -->
<sql id="psProjectJoins">
LEFT JOIN ps_customer customer ON customer.id =
a.customerid
LEFT JOIN sys_office department ON department.id = a.departmentid
LEFT JOIN sys_user projectManager ON projectManager.id =
a.project_managerid
LEFT JOIN sys_user marketer ON marketer.id = a.marketerid
LEFT JOIN ps_project_push push ON push.projectid=a.id
</sql>
<select id="findAllList" resultMap="psProjectResultMap">
SELECT
<include refid="psProjectColumns" />
,
<include refid="departmentColumns" />
,
<include refid="projectManagerColumns" />
,
<include refid="marketerColumns" />
,
<include refid="psCustomerColumns" />
,
<include refid="psProjectPushColumns" />
FROM ps_project a
<include refid="psProjectJoins" />
<where>
a.del_flag = #{DEL_FLAG_NORMAL}
</where>
<choose>
<when test="page !=null and page.orderBy != null and page.orderBy != ''">
ORDER BY ${page.orderBy}
</when>
<otherwise>
ORDER BY a.update_date DESC
</otherwise>
</choose>
</select>
<insert id="insert">
INSERT INTO ps_project(
id,
code,
name,
type,
importance_degree,
tech_state,
customerid,
departmentid,
managerid,
plan_starttime,
plan_endtime,
state,
act_starttime,
act_endtime,
sending_time,
old_plan_starttime,
old_plan_endtime,
delivery_time,
complete_status,
marketerid,
create_by,
create_date,
update_by,
update_date,
remarks,
del_flag
) VALUES (
#{id},
#{code},
#{name},
#{type},
#{importanceDegree},
#{techState},
#{customer.id},
#{department.id},
#{projectManager.id},
#{planStarttime},
#{planEndtime},
#{state},
#{actStarttime},
#{actEndtime},
#{sendingTime},
#{oldPlanStarttime},
#{oldPlanEndtime},
#{deliveryTime},
#{completeStatus},
#{marketer.id},
#{createBy.id},
#{createDate},
#{updateBy.id},
#{updateDate},
#{remarks},
#{delFlag}
)
</insert>
<update id="update">
UPDATE ps_project SET
code = #{code},
name = #{name},
type = #{type},
importance_degree = #{importanceDegree},
tech_state = #{techState},
customerid = #{customer.id},
departmentid = #{department.id},
managerid = #{projectManager.id},
plan_starttime = #{planStarttime},
plan_endtime = #{planEndtime},
state = #{state},
act_starttime = #{actStarttime},
act_endtime = #{actEndtime},
sending_time = #{sendingTime},
old_plan_starttime = #{oldPlanStarttime},
old_plan_endtime = #{oldPlanEndtime},
delivery_time = #{deliveryTime},
complete_status = #{completeStatus},
marketerid = #{marketer.id},
update_by = #{updateBy.id},
update_date = #{updateDate},
remarks = #{remarks}
WHERE id = #{id}
</update>
<update id="delete">
UPDATE ps_project SET
del_flag = #{DEL_FLAG_DELETE}
WHERE id = #{id}
</update>
</mapper>
/**
* 項目管理Entity
* @author xiaohelong
* @version 2016-01-06
*/
public class PsProject extends DataEntity<PsProject> {
private static final long serialVersionUID = 1L;
private String code; // 項目編號
private String name; // 項目名稱
private String type; // 項目類型（科研項目，仍是交付）
private String importanceDegree; // 重要程度（通常,重要,緊急）
private String techState; // 技術狀態(徹底沿用,設計更改，全新設計)
private PsCustomer customer; // 客戶單位
private Office department; // 所屬部門
private User projectManager; // 項目經理
private Date planStarttime; // 計劃開始時間
private Date planEndtime; // 計劃結束時間
private String state; // 項目當前狀態(等待開始，正常進行，交付延期，節點延期，項目暫停，項目終止，項目結束)
private Date actStarttime; // 實際開始時間
private Date actEndtime; // 實際結束時間
private Date sendingTime; // 項目下發時間
private Date oldPlanStarttime; // 計劃開始時間（只讀字段，初始化後不更改）
private Date oldPlanEndtime; // 計劃結束時間（只讀字段，初始化後不更改）
private Date deliveryTime; // 交付時間
private String completeStatus; // 完成狀況(正常完成，延期完成，未完成)
private User marketer; // 市場人員ID
private List<PsProjectPush> push; //相關領導數據表中並無，放在這裏便於表單操做，由於該字段數據送到另一個表中了。
public PsProject() {
super();
}
public PsProject(String id){
super(id);
}
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
public String getImportanceDegree() {
return importanceDegree;
}
public void setImportanceDegree(String importanceDegree) {
this.importanceDegree = importanceDegree;
}
public String getTechState() {
return techState;
}
public void setTechState(String techState) {
this.techState = techState;
}
public PsCustomer getCustomer() {
return customer;
}
public void setCustomer(PsCustomer customer) {
this.customer = customer;
}
public Office getDepartment() {
return department;
}
public void setDepartment(Office department) {
this.department = department;
}
public User getProjectManager() {
return projectManager;
}
public void setProjectManager(User projectManager) {
this.projectManager = projectManager;
}
public Date getPlanStarttime() {
return planStarttime;
}
public void setPlanStarttime(Date planStarttime) {
this.planStarttime = planStarttime;
}
public Date getPlanEndtime() {
return planEndtime;
}
public void setPlanEndtime(Date planEndtime) {
this.planEndtime = planEndtime;
}
public String getState() {
return state;
}
public void setState(String state) {
this.state = state;
}
public Date getActStarttime() {
return actStarttime;
}
public void setActStarttime(Date actStarttime) {
this.actStarttime = actStarttime;
}
public Date getActEndtime() {
return actEndtime;
}
public void setActEndtime(Date actEndtime) {
this.actEndtime = actEndtime;
}
public Date getSendingTime() {
return sendingTime;
}
public void setSendingTime(Date sendingTime) {
this.sendingTime = sendingTime;
}
public Date getOldPlanStarttime() {
return oldPlanStarttime;
}
public void setOldPlanStarttime(Date oldPlanStarttime) {
this.oldPlanStarttime = oldPlanStarttime;
}
public Date getOldPlanEndtime() {
return oldPlanEndtime;
}
public void setOldPlanEndtime(Date oldPlanEndtime) {
this.oldPlanEndtime = oldPlanEndtime;
}
public Date getDeliveryTime() {
return deliveryTime;
}
public void setDeliveryTime(Date deliveryTime) {
this.deliveryTime = deliveryTime;
}
public String getCompleteStatus() {
return completeStatus;
}
public void setCompleteStatus(String completeStatus) {
this.completeStatus = completeStatus;
}
public User getMarketer() {
return marketer;
}
public void setMarketer(User marketer) {
this.marketer = marketer;
}
public List<PsProjectPush> getPush() {
return push;
}
public void setPush(List<PsProjectPush> push) {
this.push = push;
}
}
<?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.thinkgem.jeesite.modules.sys.dao.OfficeDao">
<sql id="officeColumns">
a.id,
a.parent_id AS "parent.id",
a.parent_ids,
a.area_id AS "area.id",
a.code,
a.name,
a.sort,
a.type,
a.grade,
a.address,
a.zip_code,
a.master,
a.phone,
a.fax,
a.email,
a.remarks,
a.create_by AS "createBy.id",
a.create_date,
a.update_by AS "updateBy.id",
a.update_date,
a.del_flag,
a.useable AS useable,
a.primary_person AS "primaryPerson.id",
a.deputy_person AS "deputyPerson.id",
p.name AS "parent.name",
ar.name AS "area.name",
ar.parent_ids AS "area.parentIds",
pp.name AS "primaryPerson.name",
dp.name AS "deputyPerson.name"
</sql>
<sql id="officeJoins">
LEFT JOIN sys_office p ON p.id = a.parent_id
LEFT JOIN sys_area ar ON ar.id = a.area_id
LEFT JOIN SYS_USER pp ON pp.id = a.primary_person
LEFT JOIN SYS_USER dp ON dp.id = a.deputy_person
</sql>
<select id="findAllList" resultType="Office">
SELECT
<include refid="officeColumns"/>
FROM sys_office a
<include refid="officeJoins"/>
WHERE a.del_flag = #{DEL_FLAG_NORMAL}
ORDER BY a.code
</select>
</mapper>
參考資料： mybatis
1. http://www.mybatis.org/mybatis-3/sqlmap-xml.html#Auto-mapping app
2.http://leeyee.github.io/blog/2013/05/30/mybatis-association-autoMapping/ this
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