VALIDATION PROBLEMS WERE FOUND problem:错误

错误 VALIDATION PROBLEMS WERE FOUND problem: cvc-enumeration-valid: string value '3.0' is not a valid enumeration value for web-app-versionType in namespace http://java.sun.com/xml/ns/javaee:<null>　　因为创建项目的时候用的是JAVAEE6，所以生成web.xml文件的时候是这样的：

改为如下就ok了：

<web-app version="2.5"     xmlns="http://java.sun.com/xml/ns/javaee"     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">