ava Web项目的web.xml内错误提示，关于 web-app_3_1.xsd 的解决方案

    1. Referenced file contains errors (http://java.sun.com/xml/ns/javaee/web-app_3_1.xsd). 
    3. The errors below were detected when validating the file "web-app_3_1.xsd" via the file "web.xml". In most cases these errors can be detected by validating "web-app_3_1.xsd" directly. However it is possible that errors will only occur when web-app_3_1.xsd is validated in the context of web.xml.

    stackoverflow的答案
    Try this in your web.xml, note that xmlns points to http://xmlns.jcp.org

    1. <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
    2.          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    3.          xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee 
    4.          http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
    5.          version="3.1">

    Try removing the web module entry from org.eclipse.wst.common.project.facet.core.xml save the file, Go to ‘Project Facets’ and change it to Dynamic Web Module Version 3.1.

    Example