spring boot 五：SpringBoot整合mybatis
spring boot 五：SpringBoot整合mybatis
1 依赖配置
<parent>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-parentartifactId>
<version>2.5.4version>
parent>
<dependencies>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-webartifactId>
dependency>
<dependency>
<groupId>org.projectlombokgroupId>
<artifactId>lombokartifactId>
<version>1.18.22version>
dependency>
<dependency>
<groupId>org.mybatis.spring.bootgroupId>
<artifactId>mybatis-spring-boot-starterartifactId>
<version>1.3.2version>
dependency>
<dependency>
<groupId>mysqlgroupId>
<artifactId>mysql-connector-javaartifactId>
<scope>runtimescope>
dependency>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-configuration-processorartifactId>
<optional>trueoptional>
dependency>
dependencies>
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
*/
@Data
public 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;
@Mapper
public interface PeopleMapper {
List<PeopleDTO> queryPeopleByAge(int age);
}
在resources目录下准备mybatis的配置文件，以及Mapper文件：
mybatis-config.xml:
DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
configuration>
DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.xiaoxu.boot.mapper.PeopleMapper">
<select id="queryPeopleByAge" resultType="com.xiaoxu.boot.dto.PeopleDTO">
select * from my_people where my_age = #{age}
select>
mapper>
在application.yml中配置如下：
spring:
datasource:
username: root
password: ******
url: jdbc:mysql://localhost:3306/xiaoxu?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC
driver-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
*/
@Service
public class PeopleService {
@Autowired
PeopleMapper peopleMapper;
public List<PeopleDTO> 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
*/
@RestController
public class PeopleController {
@Autowired
PeopleService peopleService;
@GetMapping("/people")
public List<PeopleDTO> 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;
@Mapper
public interface PeopleMapper {
List<PeopleDTO> queryPeopleByAge(int age);
@Select("select * from my_people")
List<PeopleDTO> 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
*/
@Service
public class PeopleService {
@Autowired
PeopleMapper peopleMapper;
public List<PeopleDTO> getPeoples(int Age){
return peopleMapper.queryPeopleByAge(Age);
}
public List<PeopleDTO> 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
*/
@RestController
public class PeopleController {
@Autowired
PeopleService peopleService;
@GetMapping("/people")
public List<PeopleDTO> queryPeople(@RequestParam(value = "ag") int age){
return peopleService.getPeoples(age);
}
@GetMapping("/allPeople")
public List<PeopleDTO> 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：
