在pom里配置父项目parent时一直报错，上网查说重启idea，修改文件路径无果，折腾了半天才发现是自己的网络问题，导致依赖无法下载成功，心累。
二.运行springboot helloworld文件的时候报错：Failed to read candidate component classorg.springframework.beans.factory.BeanDefinitionStoreException: Failed to read candidate component class: file [C:UsershmIdeaProjectsspringBootlearntargetclassescombootMainApplication.class]; nested exception is org.springframework.core.NestedIOException: ASM ClassReader failed to parse class file - probably due to a new Java class file version that isn’t supported yet: file [C:UsershmIdeaProjectsspringBootlearntargetclassescombootMainApplication.class]; nested exception is java.lang.IllegalArgumentException: Unsupported class file major version 60
原因是JDK版本太高，换了JDK11后可以正常运行。
三.如何修改一个已建好project的JDK版本1.File->Settings->Build,Execution,Deployment->Compiler->Java Compiler->project bytecode version 选择11，target bytecode version 选择11
2.File->Project Structure->Project->Porject Sdk 选择11
Porject language level 选择11
File->Project Structure->Modules->language level 选择11
