<!-- 引入 myBatis，这是 MyBatis官方提供的适配 Spring Boot 的，而不是Spring Boot自己的-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.0</version>
        </dependency>

2.配置数据库信息 yml格式

spring:
  datasource:
     username: root
     password: 1
     url: jdbc:mysql://localhost:3306/ssmbuild?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8
     driver-class-name: com.mysql.cj.jdbc.Driver
     type: com.alibaba.druid.pool.DruidDataSource

     initialSize: 5
     minIdle: 5
     maxActive: 20
     maxWait: 60000
     timeBetweenEvictionRunsMillis: 60000
     minEvictableIdleTimeMillis: 300000
     validationQuery: SELECT 1 FROM DUAL
     testWhileIdle: true
     testOnBorrow: false
     testOnReturn: false
     poolPreparedStatements: true
     #配置监控统计拦截的filters，stat:监控统计、log4j：日志记录、wall：防御sql注入
        #如果允许时报错  java.lang.ClassNotFoundException: org.apache.log4j.Priority
        #则导入 log4j 依赖即可，Maven 地址： https://mvnrepository.com/artifact/log4j/log4j
     filters: stat,wall,log4j
     maxPoolPreparedStatementPerConnectionSize: 20
     useGlobalDataSourceStat: true
     connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=500

3.可以配置数据源

@Configuration
public class druidConfig {
        //自定义数据源
        @ConfigurationProperties(prefix = "spring.datasource")
        @Bean
        public DataSource druidDataSource() {
            return new DruidDataSource();
        }

        //配置 Druid 监控管理后台的Servlet；
        //内置 Servler 容器时没有web.xml文件，所以使用 Spring Boot 的注册 Servlet 方式
        @Bean
        public ServletRegistrationBean statViewServlet() {
            ServletRegistrationBean bean = new ServletRegistrationBean(new StatViewServlet(), "/druid/*");

            Map<String, String> initParams = new HashMap<>();
            initParams.put("loginUsername", "admin"); //后台管理界面的登录账号
            initParams.put("loginPassword", "123456"); //后台管理界面的登录密码

            //后台允许谁可以访问
            //initParams.put("allow", "localhost")：表示只有本机可以访问
            //initParams.put("allow", "")：为空或者为null时，表示允许所有访问
            initParams.put("allow", "");
            //deny：Druid 后台拒绝谁访问
            //initParams.put("kuangshen", "192.168.1.20");表示禁止此ip访问

            //设置初始化参数
            bean.setInitParameters(initParams);
            return bean;
        }

        //配置 Druid 监控 之  web 监控的 filter
        //WebStatFilter：用于配置Web和Druid数据源之间的管理关联监控统计
        public FilterRegistrationBean webStatFilter() {
            FilterRegistrationBean bean = new FilterRegistrationBean();
            bean.setFilter(new WebStatFilter());

            //exclusions：设置哪些请求进行过滤排除掉，从而不进行统计
            Map<String, String> initParams = new HashMap<>();
            initParams.put("exclusions", "*.js,*.css,/druid/*");
            bean.setInitParameters(initParams);

            //"/*" 表示过滤所有请求
            bean.setUrlPatterns(Arrays.asList("/*"));
            return bean;
        }
    }

4.编写实体类 get set 自己实现

public class User {
    private int id;
    private String name;
    private String pwd;
}

5.编写接口

@Mapper
@Repository
public interface UserMapper {
    List<User> selectAll();
    User selectSingle(int id);
    int addUser(User user);
    int delete(int id);
    int update(User user);
}

6.编写对应配置问件

<?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.yuan.dao.UserMapper">
    <select id="selectAll" resultType="User">
    select * from user
  </select>

    <select id="selectSingle" resultType="User">
    select * from user where id = #{id}
</select>

    <insert id="addUser" parameterType="User">
    insert into user (id,name,pwd) values (#{id},#{name},#{pwd})
</insert>

    <update id="update" parameterType="User">
    update user set name=#{name},pwd=#{pwd} where id = #{id}
</update>

    <delete id="delete" parameterType="int">
    delete from user where id = #{id}
</delete>
</mapper>

6.**既然已经提供了 myBatis 的映射配置文件，自然要告诉 spring boot 这些文件的位置

mybatis:
  mapper-locations: classpath:mapper/*.xml
     # 注意：对应实体类的路径
  type-aliases-package: com.yuan.pojo

7.启动测试ok