不同servlet版本的web.xml的头部信息

servlet2.5

<?xml version="1.0" encoding="UTF-8"?>
<web-app
    version="2.5"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xml="http://www.w3.org/XML/1998/namespace"
    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">

</web-app>

servlet3.0

<?xml version="1.0" encoding="UTF-8"?>
<web-app
        version="3.0"
        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_3_0.xsd">  

</web-app>

<?xml version="1.0" encoding="UTF-8"?>
<web-fragment
    version="3.0"
    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-fragment_3_0.xsd" >  

</web-fragment>