maven工程导入时解决Cannot change version of project facet Dynamic Web Module to 2.3
解决方法:修改web.xml,在头部加入内容,加入后为:
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 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_3_0.xsd">