（一）主键策略

实体类

| /*

  • @TableId:
  • value: 指定表中的主键列的列名， 如果实体属性名与列名一致，可以省略不指定.
  • type: 指定主键策略.
    /
    @TableId(value=”id” , type =IdType.AUTO)
    private Integer *id     ; // int | | —- |

（二）全局配置

配置全局配置的话,会在整个MybatisPlus里面起作用.
在 applicationContext.xml 配置

|
<bean id =”globalConfiguration” class=”com.baomidou.mybatisplus.entity.GlobalConfiguration”>

<property name=”dbColumnUnderline” value=”true”></property>


<property name=”idType” value=”0”></property>


<property name=”tablePrefix” value=”tbl_”></property>

</bean> | | —- |

还需要注意给上面的注入到Mybatis的sqlSessionFactoryBean里面才会起作用

|
<bean id=”sqlSessionFactoryBean” class=”com.baomidou.mybatisplus.spring.MybatisSqlSessionFactoryBean”>

<property name=”dataSource” ref=”dataSource”></property>
<property name=”configLocation” value=”classpath:mybatis-config.xml”></property>

<property name=”typeAliasesPackage” value=”com.atguigu.mp.beans”></property>

<property name=”globalConfig” ref=”globalConfiguration”></property>
</bean> | | —- |




也可以用配置类的方式来配置,写不同的数字的含义.

| AUTO(0, “数据库ID自增”), INPUT(1, “用户输入ID”),

/ 以下2种类型、只有当插入对象ID 为空，才自动填充。 /
ID_WORKER(2, “全局唯一ID”), UUID(3, “全局唯一ID”), NONE(4, “该类型为未设置主键类型”),
ID_WORKER_STR(5, “字符串全局唯一ID”); | | —- |



（三）查询

1．单表查询全部

传null就是查询全部
List schedulingWorkEntities =

  1.   **this**.selectByMap(**null**);<br /> <br />

2．selectOne


根据LoginAccount 查询 只能有一条记录,如果有多条记录的话,会抛异常.

| @GetMapping(“/selectOne”)
public PcUserEntity selectOne() {
PcUserEntity pcUserEntity = new PcUserEntity();
pcUserEntity.setLoginAccount(“zhangsan”);
Wrapper objectQueryWrapper = new QueryWrapper<>(pcUserEntity);
pcUserEntity = this.pcUserMapper.selectOne(objectQueryWrapper);
return pcUserEntity;
} | | —- |




3．基本多表分页查询

controller层
@PostMapping(“list2”)

public void list2 (Integer page) throws ParseException {

  1.    Integer current = 1; //当前页

Integer size = 5; //每页显示条数

Page questionStudent =

  1.      **this**.**emergencyIncidentService**.getIncidentSchedulingWorkVo(**new **Page<>(current, size));

System.out.println(questionStudent);

}
service层
public Page getIncidentSchedulingWorkVo(Page page) {

/直接调用dao层/

Page incidentSchedulingWorkVoPage =

  1.      page.setRecords(**this**.**baseMapper**.getIncidentSchedulingWorkVo(page));

return incidentSchedulingWorkVoPage;

}
dao层
public interface EmergencyIncidentDao extends BaseMapper {

  1.   /*写接口*/

List getIncidentSchedulingWorkVo(Pagination page);
dao xml

<resultMap type=”io.mergency.entity.Vo.IncidentSchedulingWorkVo” id=”incidentSchedulingWorkVoMap”>
<collection property=”emergencyIncidentEntity” ofType=”io.mergency.entity.EmergencyIncidentEntity” >
<result property=”id” column=”ID”/>
<result property=”gradeId” column=”GRADE_ID”/>
<result property=”kindId” column=”KIND_ID”/>
<result property=”entryTime” column=”ENTRY_TIME”/>
<result property=”summarize” column=”SUMMARIZE”/>
<result property=”triggerLongitude” column=”TRIGGER_LONGITUDE”/>
<result property=”triggerLatitude” column=”TRIGGER_LATITUDE”/>
<result property=”emergencyPlanid” column=”EMERGENCY_PLANID”/>
<result property=”schedule” column=”SCHEDULE”/>
<result property=”state” column=”STATE”/>
<result property=”name” column=”NAME”/>
<result property=”districtId” column=”DISTRICT_ID”/>
</collection>
<collection property=”schedulingWorkEntity” ofType=”io.mergency.entity.SchedulingWorkEntity” >
<result property=”id” column=”ID”/>
<result property=”emergencyIncidentId” column=”EMERGENCY_INCIDENT_ID”/>
<result property=”subordinateTasks” column=”SUBORDINATE_TASKS”/>
<result property=”schedule” column=”SCHEDULE”/>
<result property=”kindId” column=”KIND_ID”/>
<result property=”gradeId” column=”GRADE_ID”/>
<result property=”entryTime” column=”ENTRY_TIME”/>
<result property=”status” column=”STATUS”/>
<result property=”cerealsKind” column=”CEREALS_KIND”/>
<result property=”cerealsName” column=”CEREALS_NAME”/>
<result property=”dispatchNum” column=”DISPATCH_NUM”/>
<result property=”destination” column=”DESTINATION”/>
<result property=”finishTime” column=”FINISH_TIME”/>
<result property=”affiliatedCompanies” column=”AFFILIATED_COMPANIES”/>
<result property=”triggerLongitude” column=”TRIGGER_LONGITUDE”/>
<result property=”triggerLatitude” column=”TRIGGER_LATITUDE”/>
<result property=”radius” column=”RADIUS”/>
</collection>
</resultMap>

<select id=”getIncidentSchedulingWorkVo” resultMap=”incidentSchedulingWorkVoMap”>
select *

from EMERGENCY_INCIDENT e left join SCHEDULINGWORK s on
e.ID =s.EMERGENCY_INCIDENT_ID
</select>
如果要求状态等于1 或者 某某字段为什么直接在sql里面书写即可.


组合实体类
public class IncidentSchedulingWorkVo implements Serializable {

  1.       **private **EmergencyIncidentEntity **emergencyIncidentEntity**;
  3.       **private **SchedulingWorkEntity **schedulingWorkEntity**;<br />.....getset方法<br /> <br />打断点效果<br />![](https://cdn.nlark.com/yuque/0/2020/png/350923/1592464054560-fbeb0dcb-7262-41da-bcd9-78a93bfc28e6.png#align=left&display=inline&height=320&margin=%5Bobject%20Object%5D&originHeight=814&originWidth=1590&status=done&style=none&width=626)<br />

4．条件查询

EntityWrapper条件构造器(封装各种查询条件),注意,使用的字段都是数据库字段,不是Java实体类的字段.
MybatisPlus[笔记] - 图1
MybatisPlus[笔记] - 图2

条件分页查询,但是不建议用这个分页插件,这个只是演示,建议直接用PageHelper

| List emps =employeeMapper.selectPage(new Page(1, 2),
new EntityWrapper()
.between(“age”, 18, 50)
.eq(“gender”, 1)
.eq(“last_name”, “Tom”)
); | | —- |


Condition和 EntityWrapper 用法差不多是一样的.

| List emps = employeeMapper.selectPage(
new Page(1,2),
Condition.create()
.between(“age”, 18, 50)
.eq(“gender”, “1”)
.eq(“last_name”, “Tom”)
); | | —- |

| // 查询tblemployee表中， 性别为女并且名字中带有”老师” 或者 邮箱中带有”a”
List emps = employeeMapper.selectList(
new EntityWrapper()
.eq(“gender”, 0)
.like(“last_name”, “老师”)//or和orNew区别,注意看下面的sql的括号,or是将条件都放在一个括号里面.orNew是重新另起一个括号放条件 //.or() // SQL: (gender = ? AND last_name LIKE ? OR email LIKE ?)
.orNew() // SQL: (gender = ? AND last_name LIKE ?) OR (email LIKE ?)
.like(“email”, “a”)
);
System.**_out.println(emps);
// 查询性别为女的, 根据age进行排序(asc/desc), 简单分页
List emps = employeeMapper.selectList(
new EntityWrapper()
.eq(“gender”, 0)
.orderBy(“age”)
//.orderDesc(Arrays.asList(new String [] {“age”}))
.last(“desc limit 1,3”)
);
System.out**.println(emps); | | —- |


（四）删除操作

| @Test
public void testCommonDelete() {
//1 .根据id进行删除 Integer result = employeeMapper.deleteById(13);
System.out.println(“result: “ + result );
//2. 根据 条件进行删除 // Map columnMap = new HashMap<>();
// columnMap.put(“last_name”, “MP”);
// columnMap.put(“email”, “mp@atguigu.com”);
// Integer result = employeeMapper.deleteByMap(columnMap);
// System.out.println(“result: “ + result );

//3. 批量删除 // List idList = new ArrayList<>();
// idList.add(3);
// idList.add(4);
// idList.add(5);
// Integer result = employeeMapper.deleteBatchIds(idList);
// System.out.println(“result: “ + result );
} | | —- |



（五）更新操作

| @Test
public void testEntityWrapperUpdate() {

Employee employee = new Employee();
employee.setLastName(“苍老师”);
employee.setEmail(“cls@sina.com”);
employee.setGender(0); employeeMapper.update(employee,
new EntityWrapper()
.eq(“last_name”, “Tom”)
.eq(“age”, 44)
);
} | | —- |


（六）其它配置

1．打印SQL语句

在application.yml中添加： 注意是mybatisPlus的
# 配置slq打印日志
mybatis-plus:
configuration:
log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

如果是Mybatis的
mybatis:

configuration:

  1. **log-impl**: org.apache.ibatis.logging.stdout.StdOutImpl<br /> <br /> <br /> <br /> <br />如果是application.properties，添加：<br /># 配置slq打印日志<br />mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl

2．别名扫描

注册别名扫描后,在mapper对应的xml文件中可以直接使用类名,而不是使用权限定类名.

Spring Boot的yml配置方式:

logging:
level:
com.lanmili.dao: debug # 必须是debug级别的,info级别是不打印日志的.



 自动填充功能

自动填充，意味着就是设置默认值，不依赖数据库设置默认值，依赖程序实现。
参考:
https://blog.csdn.net/wwrzyy/article/details/85319860
https://mp.baomidou.com/guide/auto-fill-metainfo.html

 注解

 sql注入器

  Lambda表达式的支持



 ActiveRecord

在Mybatis-Plus中提供了ActiveRecord的模式，支持 ActiveRecord 形式调用，实体类只需继承 Model 类即可实现基本 CRUD 操作，简单来说就是一个实体类继承Model类，并通过注解与数据库的表名进行关联，这样就可以通过实体类直接进行表的简单增删改查操作，这样也确实极大的方便了开发人员。
这样的话不需要dao层,直接实体类就能完成基本的crud操作.



https://www.yuque.com/docs/share/ae09f675-05b2-4b4c-8a7a-5034e72d3913?#




 整合

（一）SpringBoot2.0整合


https://mp.baomidou.com/guide/quick-start.html#初始化工程