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-map

修改了一下web.xml，加入了一个<filter>，然后就报这样的错？？？

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*)".

后来在Stack Overflow上找到答案

做个搬运工，搬一下解决方法

Change the schema reference from

<!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></web-app>

to this

<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns="http://java.sun.com/xml/ns/javaee"
         version="2.5"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> 

         // your all conent goes here

</web-app>