web.xml配置servlet版本

• servlet 2.3

<?xml version="1.0" encoding="UTF-8"?>
<!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>

• servlet 2.4

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

• servlet 2.5

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
id="WebApp_ID" version="2.5">

• servlet 3.0

<?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
        http://java.sun.com/xml/ns/javaee
        http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0">

• servlet 3.1

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