spring boot 五：SpringBoot整合mybatis

1 依赖配置

org.springframework.bootspring-boot-starter-parent2.5.4 org.springframework.boot spring-boot-starter-web  org.projectlombok lombok 1.18.22  org.mybatis.spring.boot mybatis-spring-boot-starter 1.3.2  mysqlmysql-connector-javaruntimeorg.springframework.bootspring-boot-configuration-processortrue

找到mybatis-spring-boot-starter配置的依赖，即autotoconfigure包，SpringBoot的自动配置，会找到META-INF下的spring.factories,找到EnableAutoConfiguration对应的类:

可知自动配置类为MybatisAutoConfiguration：

查看配置绑定类MybatisProperties，可知yml中前缀配置为mybatis：

可知，mybatis前缀的yml配置，可以配置属性，比如：configLocation、mapperLocations、typeAliasesPackage等等。

mybatis下，又具有@NestedConfigurationProperty成员变量，故而前缀是mybatis.configuration,其中具有如下属性：

其中有非常熟悉的属性：mapUnderscoreToCamelCase，也就是数据库字段下划线转驼峰的配置。

然后，数据源有如下配置：

数据源的配置绑定是DataSourceProperties：

可知，数据源在yml中以spring.datasource为前缀，可配置连接数据源的driverClassName、url、username、password等参数。

2 使用

2.1 SpringBoot配置整合mybatis：

建表：

实体类（mybatis本质上将数据库表的数据和实体类对应，就是依靠的getter和setter，所以@Data是必须有的）：

package com.xiaoxu.boot.dto;import lombok.Data;import java.util.Date;/** * @author xiaoxu * @date 2022-03-08 * spring_boot:com.xiaoxu.boot.dto.PeopleDTO */@Datapublic class PeopleDTO {// 人的id编号long id;// 人的名字String myName;// 年龄int myAge;// 出生日期Date birthday;}

新建Mapper接口：

注意mapper接口必须要有@Mapper注解：

package com.xiaoxu.boot.mapper;import com.xiaoxu.boot.dto.PeopleDTO;import org.apache.ibatis.annotations.Mapper;import java.util.List;@Mapperpublic interface PeopleMapper {List queryPeopleByAge(int age);}

在resources目录下准备mybatis的配置文件，以及Mapper文件：

mybatis-config.xml:

select * from my_people where my_age = #{age}

在application.yml中配置如下：

spring:datasource:username: rootpassword: ******url: jdbc:mysql://localhost:3306/xiaoxu?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTCdriver-class-name: com.mysql.cj.jdbc.Driver#mybatis的相关配置mybatis:#mapper配置文件mapper-locations: classpath:mapper/*.xml##mybatis配置文件#config-location: classpath:mybatis-config.xml#config-location和configuration不能同时存在#开启驼峰命名configuration:map-underscore-to-camel-case: true

插入测试数据：

service层实现：

package com.xiaoxu.service;import com.xiaoxu.boot.dto.PeopleDTO;import com.xiaoxu.boot.mapper.PeopleMapper;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;import java.util.List;/** * @author xiaoxu * @date 2022-03-08 * spring_boot:com.xiaoxu.service.PeopleService */@Servicepublic class PeopleService {@AutowiredPeopleMapper peopleMapper;public List getPeoples(int Age){return peopleMapper.queryPeopleByAge(Age);}}

controller层实现：

package com.xiaoxu.boot.controller;import com.xiaoxu.boot.dto.PeopleDTO;import com.xiaoxu.service.PeopleService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.RequestParam;import org.springframework.web.bind.annotation.RestController;import java.util.List;/** * @author xiaoxu * @date 2022-03-08 * spring_boot:com.xiaoxu.boot.controller.PeopleController */@RestControllerpublic class PeopleController {@AutowiredPeopleService peopleService;@GetMapping("/people")public List queryPeople(@RequestParam(value = "ag") int age){return peopleService.getPeoples(age);}}

执行结果无误：

2.2 SpringBoot注解整合mybatis：

修改Mapper接口文件：

package com.xiaoxu.boot.mapper;import com.xiaoxu.boot.dto.PeopleDTO;import org.apache.ibatis.annotations.Mapper;import org.apache.ibatis.annotations.Select;import java.util.List;@Mapperpublic interface PeopleMapper {List queryPeopleByAge(int age);@Select("select * from my_people")List queryAllPeople();}

修改服务层：

package com.xiaoxu.service;import com.xiaoxu.boot.dto.PeopleDTO;import com.xiaoxu.boot.mapper.PeopleMapper;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;import java.util.List;/** * @author xiaoxu * @date 2022-03-08 * spring_boot:com.xiaoxu.service.PeopleService */@Servicepublic class PeopleService {@AutowiredPeopleMapper peopleMapper;public List getPeoples(int Age){return peopleMapper.queryPeopleByAge(Age);}public List getAllPeople(){return peopleMapper.queryAllPeople();}}

增加controller：

package com.xiaoxu.boot.controller;import com.xiaoxu.boot.dto.PeopleDTO;import com.xiaoxu.service.PeopleService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.RequestParam;import org.springframework.web.bind.annotation.RestController;import java.util.List;/** * @author xiaoxu * @date 2022-03-08 * spring_boot:com.xiaoxu.boot.controller.PeopleController */@RestControllerpublic class PeopleController {@AutowiredPeopleService peopleService;@GetMapping("/people")public List queryPeople(@RequestParam(value = "ag") int age){return peopleService.getPeoples(age);}@GetMapping("/allPeople")public List queryAllPeople(){return peopleService.getAllPeople();}}

结果返回无误：

2.3 在配置类上增加@MapperScan注解，扫描某个包下的全部Mapper文件：

如果每个Mapper接口文件上增加@Mapper比较麻烦，那么可以在配置类，如主程序类上，增加@MapperScan注解，以及扫描路径，效果和@Mapper一致：

主程序类增加@MapperScan注解：

重新执行效果一致：

spring boot 五：SpringBoot整合mybatis