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

<?xml version="1.0" encoding="UTF-8"?> 
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd"> 
<web-app>

解决方案 
2：删除<!DOCTYPE 。。。。这段内容