1、异常：Field bookMapper in com.aaa.lee.springboot.service.BookService required a bean of type ‘com.aaa.lee.springboot.mapper.BookMapper‘ that could not be found.
原因：在service中使用@Autowired注解注入了mapper，最终mapper没有注入成功，也就是mapper并没有以bean的形式配置进application.xml配置文件(没有mapper的扫描器)
需要添加@Mapper注解；
2、使用注解的形式写上SQL语句，实体类的属性和数据库的字段映射问题：
当使用@Select @Update @Delete @Insert来替代mapper.xml的时候，需要把数据库表中字段名和实体类的属性要完全一致！
1 package com.aaa.liu.springboot.mapper; 2 3 import com.aaa.liu.springboot.model.Book; 4 import org.apache.ibatis.annotations.Delete; 5 import org.apache.ibatis.annotations.Insert; 6 import org.apache.ibatis.annotations.Select; 7 import org.apache.ibatis.annotations.Update; 8 9 import java.util.List; 10 11 12 /** 13 * @Author 刘其佳 14 * 2019/8/16 -- 20:48 15 * @Version 1.0 16 */ 17 public interface BookMapper { 18 //查询 19 @Select("select id,book_name bookName,book_price bookPrice from book ") 20 List<Book> selectAll(); 21 22 //添加 23 @Insert("insert into book(book_name,book_price) values(#{bookName},#{bookPrice})") 24 int addBook(Book book); 25 26 //根据ID进行查询 27 @Select("select id,book_name bookName,book_price bookPrice from book where id=#{id}") 28 List<Book> selectById(int id); 29 30 //修改 31 @Update("update book set book_name=#{bookName},book_price=#{bookPrice} where id=#{id}") 32 int updateBook(Book book); 33 34 //删除 35 @Delete("delete from book where id=#{id}") 36 int deleteBook(int id); 37 }
原文：https://www.cnblogs.com/liuqijia/p/11373997.html