不同版本（2.3-3.1）web.xml文件的schema头部声明

1. Servlet 3.1

Java EE 7 XML schema，命名空间是 http://xmlns.jcp.org/xml/ns/javaee/

[html]  view plain  copy

1. <?xml version="1.0" encoding="UTF-8"?>  
2. <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"   
3.         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
4.         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee  
5.          http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"  
6.         version="3.1">  
7.           
8. </web-app>  

2. Servlet 3.0

Java EE 6 XML schema，命名空间是 http://java.sun.com/xml/ns/javaee

[html]  view plain  copy

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

3. Servlet 2.5

Java EE 5 XML schema，命名空间是 http://java.sun.com/xml/ns/javaee

[html]  view plain  copy

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

4. Servlet 2.4

Java EE 1.4 XML schema, 命名空间是 http://java.sun.com/xml/ns/j2ee

[html]  view plain  copy

1. <?xml version="1.0" encoding="UTF-8"?>  
2. <web-app 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  
5.           http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"  
6.           version="2.4">  
7.   
8. </web-app>  

5. Servlet 2.3

Java EE 1.3 DTDs schema，这个版本的web.xml文件太老了，强烈建议升级

[html]  view plain  copy

1. <!DOCTYPE web-app PUBLIC  
2.  "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"  
3.  "http://java.sun.com/dtd/web-app_2_3.dtd" >  
4.   
5. <web-app>  
6.   <display-name>Servlet 2.3 Web Application</display-name>  
7. </web-app>