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

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

2. Servlet 3.0

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

<?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_3_0.xsd"  
          version="3.0">  
            
</web-app>

3. Servlet 2.5

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

<?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>

4. Servlet 2.4

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

<?xml version="1.0" encoding="UTF-8"?>  
<web-app 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"  
          version="2.4">  
  
</web-app>

5. Servlet 2.3

Java EE 1.3 DTDs schema，這個版本的web.xml文件太老了，強烈建議升級

<!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>  
  <display-name>Servlet 2.3 Web Application</display-name>  
</web-app>

不同版本（2.3-3.1）web.xml文件的schema頭部聲明