web.xml的头信息怎么写

1. <?xml version="1.0" encoding="ISO-8859-1"?>  
2. <!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd">  
3.    
4. <web-app>  
5.    
6. </web-app> 
   

1. <?xml version="1.0" encoding="UTF-8"?>  
2. <web-app id="WebApp_9" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"   
3.     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
4.     xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">  
5.    
6. </web-app> 
   

1. <?xml version="1.0" encoding="UTF-8"?>  
2.    
3. <web-app xmlns="http://java.sun.com/xml/ns/javaee"  
4.    
5. xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
6.    
7. xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"  
8.    
9. version="2.5">  
10.    
11. </web-app> 
    

1. <?xml version="1.0" encoding="UTF-8"?>  
2.    
3. <web-app  
4.         version="3.0"  
5.         xmlns="http://java.sun.com/xml/ns/javaee"  
6.         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
7.         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">  
8.    
9. </web-app>