web.xml; lineNumber: 2; columnNumber: 193; 已经为元素 "web-app" 指定属性 "xmlns"。

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee"
	<span style="color:#FF0000;"><em><strong>xmlns="http://java.sun.com/xml/ns/javaee"</strong></em></span>
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
	id="DogStoreApp" version="2.5">

重复了