使用IDEA創建的spring boot項目，目前是空項目，運行DemoApplication文件的時候，出現如下錯誤：2019-05-16 17:36:41.215 INFO 22276 --- [ main] springboot02.demo.DemoApplication : Starting DemoApplication on lijinxiadeMacBook-Pro.local with PID 22276 (/data/yx/javacode/spring-boot-samples-master/demo/target/classes started by lijinxia in /data/yx/javacode/spring-boot-samples-master/demo)2019-05-16 17:36:41.217 INFO 22276 --- [ main] springboot02.demo.DemoApplication : No active profile set, falling back to default profiles: default2019-05-16 17:36:42.118 INFO 22276 --- [ main] springboot02.demo.DemoApplication : Started DemoApplication in 16.227 seconds (JVM running for 21.986)application.properties 文件是空的pom.xml文件的內容：<?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 http://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>2.1.5.RELEASE</version>    <relativePath/> <!-- lookup parent from repository --></parent><groupId>springboot02</groupId><artifactId>demo</artifactId><version>0.0.1-SNAPSHOT</version><name>demo</name><description>Demo project for Spring Boot</description><properties>    <java.version>1.8</java.version></properties><dependencies>    <dependency>        <groupId>org.springframework.boot</groupId>        <artifactId>spring-boot-starter-web</artifactId>    </dependency>    <dependency>        <groupId>org.springframework.boot</groupId>        <artifactId>spring-boot-starter-test</artifactId>        <scope>test</scope>    </dependency></dependencies><build>    <plugins>        <plugin>            <groupId>org.springframework.boot</groupId>            <artifactId>spring-boot-maven-plugin</artifactId>        </plugin>    </plugins></build></project>那這樣看的話，是哪里出了問題那？