web.xml 各個版本的 dtd

2.3

<?xml version="1.0" encoding="ISO-8859-1"?>  
 <!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd">  
    
<web-app>  
   
</web-app>

2.4

<?xml version="1.0" encoding="UTF-8"?>  
 <web-app id="WebApp_9" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"   
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">  
    
 </web-app>

2.5

<?xml version="1.0" encoding="UTF-8"?>  
   
 <web-app 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"  
   
version="2.5">  
   
 </web-app>

3.0

<?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>

web-fragment.xml

<web-fragment 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" version="3.0">  
   
 </web-fragment>