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>
解决方法：
因为web工程中 j2ee版本太高，j2ee 6.0 改为 j2ee 5.0即可
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>
解决方法：
因为web工程中 j2ee版本太高，j2ee 6.0 改为 j2ee 5.0即可