SpringBoot整合mybatis的方法详解

目录

• 1依赖配置
• 2使用
• 2.1SpringBoot配置整合mybatis：
• 2.2SpringBoot注解整合mybatis：
• 2.3在配置类上增加@MapperScan注解，扫描某个包下的全部Mapper文件：
• 总结

1 依赖配置

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.5.4</version>
</parent>
<dependencies>
    <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-web</artifactId>
     </dependency>
     <dependency>
         <groupId>org.projectlombok</groupId>
         <artifactId>lombok</artifactId>
         <version>1.18.22</version>
     </dependency>
	 <dependency>
	     <groupId>org.mybatis.spring.boot</groupId>
	     <artifactId>mybatis-spring-boot-starter</artifactId>
	     <version>1.3.2</version>
	 </dependency>
	 <!--     spring连接驱动时，如com.mysql.cj.jdbc.Driver使用   -->
     <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-configuration-processor</artifactId>
        <optional>true</optional>
    </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-confi.xml:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
</configuration>

<?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.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：

总结

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