springboot集成mybatis

1、MyBatis + XML

1.1、引入依赖

<?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>2.3.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.eliang</groupId>
    <artifactId>springboot04</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot04</name>
    <description>Demo project for Spring Boot</description>

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

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency> <!-- 本示例，我们使用 MySQL -->
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.48</version>
        </dependency>

        <!-- 实现对 MyBatis 的自动化配置 -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.1</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

1.2、Application

添加@MapperScan,扫描mapper接口所在的包

@SpringBootApplication
@MapperScan("com.eliang.springboot04.mapper")
public class Springboot04Application {

    public static void main(String[] args) {
        SpringApplication.run(Springboot04Application.class, args);
    }

}

1.3、配置文件

#application.yml
spring:
  # datasource 数据源配置内容
  datasource:
    url: jdbc:mysql://192.168.8.150:3306/test_mybatis?useSSL=false&useUnicode=true&characterEncoding=UTF-8
    driver-class-name: com.mysql.jdbc.Driver
    username: root
    password: 123456

# mybatis 配置内容
mybatis:
  mapper-locations: classpath:mapper/*.xml # 配置 Mapper XML 地址
  type-aliases-package: com.eliang.springboot04.po # 配置数据库实体包路径
  configuration:
    map-underscore-to-camel-case: true # 使用驼峰命名法转换字段。
#显示执行的sql  mapper接口的包路径
logging:
  level:
    com:
      eliang:
        springboot04:
          mapper: debug

1.4、User实体类

@Data
public class User {
    private Integer id;

    private String username;

    private String password;

    private Date createTime;
}

建表语句：

CREATE TABLE `users` (
  `id` int(11) NOT NULL AUTO_INCREMENT COMMENT 'id',
  `username` varchar(64) COLLATE utf8mb4_bin DEFAULT NULL COMMENT '用户名',
  `password` varchar(32) COLLATE utf8mb4_bin DEFAULT NULL COMMENT '密码',
  `create_time` datetime DEFAULT NULL COMMENT '创建时间',
  PRIMARY KEY (`id`),
  UNIQUE KEY `idx_username` (`username`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;

1.5、UserMapper

@Repository
public interface UserMapper {

    int insert(User user);

}

在resources/mapper下对应的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="com.eliang.springboot04.mapper.UserMapper">

    <sql id="FIELDS">
        id, username, password, create_time
    </sql>

    <insert id="insert" parameterType="User" useGeneratedKeys="true" keyProperty="id">
        INSERT INTO users (
          username, password, create_time
        ) VALUES (
          #{username}, #{password}, #{createTime}
        )
    </insert>

</mapper>

1.6、测试类UserMapperTest

@SpringBootTest(classes = Springboot04Application.class)
class UserMapperTest {

    @Autowired
    UserMapper userMapper;


    @Test
    void insert() {
        User user = new User();
        user.setUsername("test2");
        user.setPassword("123456");
        user.setCreateTime(new Date());
        userMapper.insert(user);
    }

}

1.7、插件

idea的插件free mybatis plugin

• 提供xml和dao层的互相跳转功能，箭头形状。
• mapper生成xml文件
• mybatis自动补全及语法错误提示
• 集成mybatis generator gui界面

2、MyBatis + 注解

在 [application.yaml]配置文件中，我们可以删除 mapper-locations 配置项。

可以删除 UserMapper.xml 配置文件。

UserMapper.java

@Repository
public interface UserMapper {

    @Insert("INSERT INTO users(username, password, create_time) VALUES(#{username}, #{password}, #{createTime})")
    @Options(useGeneratedKeys = true, keyProperty = "id", keyColumn = "id")
    int insert2(User user);
}