报错全部内容：Failure to transfer com.thoughtworks.xstream:xstream:jar:1.3.1 from https://repo.maven.apache.org/maven2 was cached in the local repository, resolution will not be reattempted until the update

常会遇到报找不到类的问题，有时是没有引入相关类，但很多时候明明是有的，现把原因简单总结如下：1、java.lang.ClassNotFoundException: com.alibaba.nacos.client.logging.NacosLogging调试spring cloud alibaba总报这个错，查到对应包nacos-client-2.0.3有此类，双击无法打开，果断判断是包下载问题，