Mybatis入门（五）SpringBoot整合Mybatis_1

文章目录

前言

Mybatis-SpringBoot整合：http://mybatis.org/spring-boot-starter/mybatis-spring-boot-autoconfigure/index.html

一、导入依赖

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.13</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>cn.cy</groupId>
    <artifactId>mybatis_springboot_demo01</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>mybatis_springboot_demo01</name>
    <description>Springboot-Mybatis Study</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <!--springboot-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <!--springboot整合mybatis-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.3</version>
        </dependency>
        <!--mysql-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <!--springboot测试-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <!--lombok-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.20</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>

    <build>
        <!--springboot整合maven插件-->
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

二、编写配置文件

SpringBoot项目配置文件有两种：

application.properties（创建项目默认）

spring.datasource.url=jdbc:mysql://localhost:3306/demo_admin?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=Asia/Shanghai
spring.datasource.username=root
spring.datasource.password=root

application.yml

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/demo_admin?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=Asia/Shanghai
    username: root
    password: root

启动项目测试是否能正常启动，如启动失败遇到下述问题，可以参考下面的解决方案

APPLICATION FAILED TO START 异常报错原因及解决方案

二、编写User实体类

User

@Data
@Accessors(chain = true)
public class User implements Serializable {
    private Integer id;
    private String name;
    private Integer age;
    private String sex;
}

三、编写持久层UserMapper接口

UserMapper

@Mapper // 这里@Mapper注解加不加皆可
public interface UserMapper {
    List<User> getAllUser();
}

这里 @Mapper注解加不加皆可

四、编写UserMapper映射文件

UserMapper.xml

<?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="cn.cy.mapper.UserMapper">
    <select id="getAllUser" resultType="cn.cy.pojo.User">
        select * from demo_user
    </select>
</mapper>

五、在配置类上添加@MapperScan注解

1. 单独写一个配置类 MybatisConfig

@Configuration
@MapperScan("cn.cy.demo.mapper")
public class MybatisConfig {
}

2. 直接定义在启动类上

@SpringBootApplication
@MapperScan("cn.cy.demo.mapper")
public class MybatisSpringbootDemo01Application {
    public static void main(String[] args) {
        SpringApplication.run(MybatisSpringbootDemo01Application.class, args);
    }
}

六、修改项目配置文件（根据配置文件的类型选择一种即可）

application.properties

mybatis.mapper-locations=classpath:mappers/*.xml

application.yml

mybatis:
  mapper-locations: classpath:mappers/*.xml

七、编写UserMapperTests测试类

@SpringBootTest
public class UserMapperTests {

    @Autowired
    UserMapper userMapper;

    @Test
    void testGetAllUser() {
        List<User> users = userMapper.getAllUser();
        System.out.println(users); // [User(id=1, name=zs, age=18, sex=男), User(id=2, name=ls, age=20, sex=男), User(id=3, name=xiaohong, age=18, sex=女)]
    }
}