mybatis-plus写自定义的sql的时候报错,跟着视频的代码敲,视频里面没有报错,自己的报错了
MainApplication.java
package org.example.smile;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@MapperScan("org.example.smile.mapper")
@SpringBootApplication
public class MainApplication {
public static void main(String[] args) {
SpringApplication.run(MainApplication.class,args);
}
}
application.yml
server:
port: 8888
spring:
datasource:
type: com.zaxxer.hikari.HikariDataSource
driver-class-name: com.mysql.cj.jdbc.Driver
url: jdbc:mysql://localhost:3306/hd?serverTimezone=GMT&useUnicode=true&characterEncoding=utf-8&useSSL=false
username: root
password: root
mybatis-plus:
configuration:
log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
NewsMapper.java
package org.example.smile.mapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import org.example.smile.pojo.News;
import org.springframework.stereotype.Repository;
@Repository
public interface NewsMapper extends BaseMapper<News> {
News getNewsById();
}
NewsMapper.xml
mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.example.smile.mapper.NewsMapper">
<select id="getNewsById" resultType="News">
select * from hd_news
select>
mapper>
总感觉是mapper.xml那一块出了问题,但怎么都找不到问题出在哪,我知道有一个叫mapper-locations扫描xml的配置,但视频里默认没写,默认不写的时候就是在resources下创一个mapper路径就可以扫描了
让mybatis-plus可以自己自定义sql语句
MybatisTest测试类的13行代码发出来看下,空指针异常了。