1、错误：
我用Springboot3.1.7整合myBatisplus3.5.3时，出现下面的错误：
Bean named ‘ddlApplicationRunner’ is expected to be of type ‘org.springframework.boot.Runner’ but was actually of type ‘org.springframework.beans.factory.support.NullBean’
明明我的代码刚开始写，就起了一个头，竟然报错了！
demo框架如下：
(1)Demo1Application.java
(2)controller层：JOJOController.java
(3)service层：JOJOService.java
(4)mapper层：JOJOMapper.java
(5)数据库实体类：jojo.java
(6)pom.xml
<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>3.1.7</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.example</groupId> <artifactId>demo1</artifactId> <version>0.0.1-SNAPSHOT</version> <name>demo1</name> <description>demo1</description> <properties> <java.version>17</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>com.mysql</groupId> <artifactId>mysql-connector-j</artifactId> <scope>runtime</scope> </dependency> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <optional>true</optional> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>com.baomidou</groupId> <artifactId>mybatis-plus-boot-starter</artifactId> <version>3.5.3</version> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> <configuration> <image> <builder>paketobuildpacks/builder-jammy-base:latest</builder> </image> <excludes> <exclude> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> </exclude> </excludes> </configuration> </plugin> </plugins> </build> </project>是不是看起来非常正确！！没感觉有什么问题，有很多博客说要加上@MapperScan(“com.example.demo1.mapper”)之类的，但是我是加上了，还是有错误。
坑就在于springboot3.1.7需要更高版本的myBatisPlus！
2、解决办法：
把myBatisplus的版本升级到3.5.5，就可以了！！！
把
<dependency> <groupId>com.baomidou</groupId> <artifactId>mybatis-plus-boot-starter</artifactId> <version>3.5.3</version> </dependency>改为
<dependency> <groupId>com.baomidou</groupId> <artifactId>mybatis-plus-boot-starter</artifactId> <version>3.5.5</version> </dependency>
)
