IntelliJ IDEA项目导入时报错：The import javax.servlet.http.HttpServletRequest cannot be resolved

IntelliJ IDEA项目导入时报错：

The import javax.servlet.http.HttpServletRequest cannot be resolved

翻译一下错误信息是说 javax.servlet.http.HttpServletRequest 包未被引用，

解决方法：

Ctrl+Shift+Alt+s，进入Project Structure

选择 Libraries，加号，找到 tomcat 里面的 servlet-api.jar