一.前言

二.springboot创建项目

首先，给大家看一下我的项目结构

springboot的版本为：2.1.9 具体可以看一下我的pom文件

2.1 依赖pom文件

以下就是我该演示项目的所有依赖，h2的版本交给springboot去进行确定

    <properties>
        <java.version>1.8java.version>
    properties>

    <dependencies>
        
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        
        <dependency>
            <groupId>org.mybatis.spring.bootgroupId>
            <artifactId>mybatis-spring-boot-starterartifactId>
            <version>2.1.1version>
        dependency>
        
        <dependency>
            <groupId>com.h2databasegroupId>
            <artifactId>h2artifactId>
            <scope>runtimescope>
        dependency>
        <dependency>
            <groupId>org.projectlombokgroupId>
            <artifactId>lombokartifactId>
            <optional>trueoptional>
        dependency>
        
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
        dependency>
    dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-maven-pluginartifactId>
            plugin>
        plugins>
        
        <resources>
            <resource>
                <directory>class="lazy" data-src/main/javadirectory>
                <includes>
                    <include>**
@SpringBootApplication
@MapperScan("com.springboot.*.mapper")
public class MybatisApplication {

    public static void main(String[] args) {
        SpringApplication.run(MybatisApplication.class, args);
    }

}

2.5 mapper.java和mapper.xml

配置后，由mybatis进行实体类的映射

public interface CatMapper {

    List selectAll();

}

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.springboot.mybatis.mapper.CatMapper">
    <select id="selectAll" resultType="com.springboot.mybatis.entity.Cat">
        SELECT * from cat
    select>
mapper>

2.6 案例的entity

与数据库的实体对应

@Data
public class Cat {
    private Long id;
    private String name;
    private Integer age;
    private String color;
    private Double score;
}

2.7 service 和 impl

public interface CatService {

    
    String meow();

    List list();

}

@Service
public class CatServiceImpl implements CatService {

    @Autowired
    private CatMapper catMapper;

    @Override
    public String meow() {
        return "瞄";
    }

    @Override
    public List list() {
        return catMapper.selectAll();
    }
}

2.8 建立测试类

@RunWith(SpringRunner.class)
@SpringBootTest
public class MybatisApplicationTests {

    @Autowired
    private CatService catService;

    @Test
    public void contextLoads() {
        List list = catService.list();
        list.forEach(System.out::println);
    }

}

三 测试结果

Creating a new SqlSession
SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@6caf7803] was not registered for synchronization because synchronization is not active
JDBC Connection [HikariProxyConnection@408543908 wrapping conn0: url=jdbc:h2:mem:test user=ROOT] will not be managed by Spring
==>  Preparing: SELECT * from cat 
==> Parameters: 
<==    Columns: ID, NAME, AGE, COLOR, SCORE
<==        Row: 1, Jone, 18, 黃色, 0.4
<==        Row: 2, Jack, 20, 白色, 0.5
<==        Row: 3, Tom, 28, 金色, 0.1
<==        Row: 4, Sandy, 21, 紅色, 0.8
<==        Row: 5, Billie, 24, 綠色, 0.7
<==      Total: 5
Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@6caf7803]
Cat(id=1, name=Jone, age=18, color=黃色, score=0.4)
Cat(id=2, name=Jack, age=20, color=白色, score=0.5)
Cat(id=3, name=Tom, age=28, color=金色, score=0.1)
Cat(id=4, name=Sandy, age=21, color=紅色, score=0.8)
Cat(id=5, name=Billie, age=24, color=綠色, score=0.7)

四 打开h2的web浏览页面

运行main方法

浏览器输入 

http://localhost:8081/h2-console

账号 root 密码 test，进去

查看

结语

本人长期从事java开发，如果有什么疑问，可以留言，我会及时解答

附录