如果在刚刚启动tomcat时出现以下问题：
Error running Tomcat 8.5.31: Error copying configuration files from /usr/local/apache-tomcat-8.5.3/conf to /Users/zhouyuchen/Library/Caches/IntelliJIdea2016.1/tomcat/Tomcat_8_5_31_ttt/conf: Directory is invalid /usr/local/apache-tomcat-8.5.3/conf/Catalina
经过实验解决方法如下：
首先点击File–>Project Structure–>Path, 把path路径改为/web/WEB_INF/classes , 然后在运行tomcat，可能会出现权限问题，例如：
Error running tomcat8.5.15: Error copying configuration files from /home/dell/software/apache-tomcat-8.5.15/conf to /home/dell/.IntelliJIdea2017.1/system/tomcat/Unnamed_LibManage/conf: /home/dell/software/apache-tomcat-8.5.15/conf/Catalina/localhost (权限不够)
这时需要在命令行界面递归修改tomcat主目录权限，命令如下：
chmod -R 755 apache-tomcat8.5.15
此时再运行tomcat，便可以了。