servlet 同版本對應的Tomcat版本 ，不同版本的web.xml寫法

Tomcat 實現了 java Servlet規范、java Servlet Pages技術，不同版本的Tomcat 支持不同的serlet和JSP 規范，servlet和jsp與tomcat 的版本對應關系如下：

web.xml v2.3

<?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>  

web.xml v2.4

<?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>  

web.xml v2.5

<?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>  

web.xml 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>  

<?xml version="1.0" encoding="UTF-8"?> 
<!DOCTYPE xml>
<web-app  
        version="4.0"
        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_4_0.xsd">
         
</web-app>