The type javax.servlet.http.HttpServletRequest cannot be resolved. It is indirectly referenced from

String realpath = ServletActionContext.getServletContext().getRealPath("/img_head");   

编写上面代码时出现下面的错误提示：

The type javax.servlet.http.HttpServletRequest cannot be resolved. It is indirectly referenced from required .class files

解决该问题需要将servlet-api.jar文件复制到WEB-INF/lib文件夹中。