SpringBoot入门

　　1.mvn install可重新生成修改测试
　　2.
　　Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type ‘com.zyd.mapper.xxMapper’ available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
　　由于spring 容器没有扫描到对应的信息
　　在启动类加上,即可@MapperScan({＂com.itheima＂})package com.itheima.springboot_8_mybatis;  import org.mybatis.spring.annotation.MapperScan; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication;  @SpringBootApplication @MapperScan({＂com.itheima＂})  public class Springboot8MybatisApplication {      public static void main(String[] args) {         SpringApplication.run(Springboot8MybatisApplication.class, args);     }  }
　　3.实例如下package com.itheima.dao;  import com.itheima.domain.Book; import org.apache.ibatis.annotations.Mapper; import org.apache.ibatis.annotations.Select;  @Mapper public interface BookDao {     @Select(＂select * from tbl_book where id = #{id}＂)     public Book getById(Integer id); } package com.itheima.domain;  public class Book {     private Integer id;     private String name;     private String type;     private String description;      @Override     public String toString() {         return ＂Book{＂ +                 ＂id=＂ + id +                 ＂, name=＂＂ + name + ＂＂＂ +                 ＂, type=＂＂ + type + ＂＂＂ +                 ＂, description=＂＂ + description + ＂＂＂ +                 ＂}＂;     }      public Integer getId() {         return id;     }      public void setId(Integer id) {         this.id = id;     }      public String getName() {         return name;     }      public void setName(String name) {         this.name = name;     }      public String getType() {         return type;     }      public void setType(String type) {         this.type = type;     }      public String getDescription() {         return description;     }      public void setDescription(String description) {         this.description = description;     } } --启动类  package com.itheima.springboot_8_mybatis;  import org.mybatis.spring.annotation.MapperScan; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication;  @SpringBootApplication @MapperScan({＂com.itheima＂})  public class Springboot8MybatisApplication {      public static void main(String[] args) {         SpringApplication.run(Springboot8MybatisApplication.class, args);     }  }  --application.yml  spring:   datasource:     driver-class-name: com.mysql.cj.jdbc.Driver     url: jdbc:mysql://localhost:3306/ssm_db?serverTimezone=UTC     username: root     password: caicai123     type: com.alibaba.druid.pool.DruidDataSource--test  package com.itheima.springboot_8_mybatis;  import com.itheima.dao.BookDao; import com.itheima.domain.Book; import org.junit.jupiter.api.Test; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.test.context.SpringBootTest;  @SpringBootTest class Springboot8MybatisApplicationTests {      @Autowired     private BookDao bookDao;      @Test     void testGetById() {         Book book = bookDao.getById(1);         System.out.println(book);     }   } --pom.xml  <?xml version=＂1.0＂ encoding=＂UTF-8＂?>      4.0.0              org.springframework.boot         spring-boot-starter-parent         2.5.0          com.itheima     springboot_08_mybatis     0.0.1-SNAPSHOT              1.8                                org.mybatis.spring.boot             mybatis-spring-boot-starter             2.2.0                                mysql             mysql-connector-java             runtime                                org.springframework.boot             spring-boot-starter-test             test                                com.alibaba             druid             1.1.16                                                           org.springframework.boot                 spring-boot-maven-plugin                             
　　文件结构如下