刚开始用IDEA会有很多不习惯
项目报错：
1 Project build error: Non-resolvable parent POM for com.ks:my-springboot1:0.0.1-SNAPSHOT: Failure to transfer 2 org.springframework.boot:spring-boot-starter-parent:pom:2.0.2.RELEASE from https://repo.maven.apache.org/maven2 was cached in the local 3 repository, resolution will not be reattempted until the update interval of central has elapsed or updates are forced. Original error: Could not 4 transfer artifact org.springframework.boot:spring-boot-starter-parent:pom:2.0.2.RELEASE from/to central (https://repo.maven.apache.org/maven2): 5 repo.maven.apache.org and 'parent.relativePath' points at no local POM
把所在jar删了，重新下载后，项目仍然显示这个错误。
解决方法：项目有改动之后，IDEA右下角会自动出现Import 的弹框:
点击Import，重新加载编译，这样刚才改动的内容才能生效。
或者点击“Enable Auto-Import”使每次引用的jar包自动导入