用ORM操作SQL数据库

Mybatis

1.依赖

<dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
    </dependency>
    <dependency>
      <groupId>org.mybatis.spring.boot</groupId>
      <artifactId>mybatis-spring-boot-starter</artifactId>
      <version>2.1.2</version>
    </dependency>

2.配置

spring:
  datasource:
    driverClassName: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/xz_test?serverTimezone=Hongkong&useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&transformedBitIsBoolean=true&autoReconnect=true&failOverReadOnly=false&useSSL=false
    username: root
    password: 123456
    initialSize: 10
    maxActive: 20
    minIdle: 1
    maxWait: 60000
mybatis:
  mapper-locations: classpath:mappers/*.xml

3.代码示例
mapper的扫描只用@mapperScan注解就行, 至于idea编译报错, 装个mybatis的插件就行, 参照:
https://www.imooc.com/article/287865

---------------dao
public interface UserMapper {
  List<User> listAll();
}
---------------mapper
    <?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="top.xinzhang0618.springboot.demo.UserMapper">
  <resultMap id="resultMap" type="top.xinzhang0618.springboot.demo.User">
    <id column="user_id" property="userId"/>
    <result column="created_time" property="createdTime"/>
    <result column="department_id" property="departmentId"/>
    <result column="department_name" property="departmentName"/>
    <result column="email" property="email"/>
    <result column="head_url" property="headUrl"/>
    <result column="is_enable" property="enable"/>
    <result column="is_system" property="system"/>
    <result column="login_name" property="loginName"/>
    <result column="login_password" property="loginPassword"/>
    <result column="mobile" property="mobile"/>
    <result column="modified_time" property="modifiedTime"/>
    <result column="nickname" property="nickname"/>
    <result column="remark" property="remark"/>
    <result column="telephone" property="telephone"/>
    <result column="user_name" property="userName"/>
  </resultMap>
  <sql id="columns">created_time,department_id,department_name,email,head_url,is_enable,is_system,login_name,login_password,mobile,modified_time,nickname,remark,telephone,user_id,user_name</sql>
  <select id="listAll" resultMap="resultMap">
    select
    <include refid="columns"/>
    from oms_user
  </select>
</mapper>
---------------启动类
@SpringBootApplication
@MapperScan("top.xinzhang0618.springboot.demo")
public class SpringbootDemoApplication {
  public static void main(String[] args) {
    SpringApplication.run(SpringbootDemoApplication.class, args);
  }
}
---------------测试
  @Autowired
  private UserMapper userMapper;
  @Test
  public void test() {
    List<User> list = userMapper.listAll();
    System.out.println(list);
  }