Error-The content of element type "web-app" must match "(icon?,display-

错误描述

The content of element type "web-app" must match "(icon?,display- name?,description?,distributable?,context-param*,filter*,filter-mapping*,listener*,servlet*,servlet-mapping*,session-config?,mime-mapping*,welcome-file-list?,error-page*,taglib*,resource-env-
  ref*,resource-ref*,security-constraint*,login-config?,security-role*,env-entry*,ejb-ref*,ejb-local-ref*)".- No grammar constraints (DTD or XML schema) detected for the document.

解决办法

删除<!DOCTYPE 。。。。这段内容