不同版本（2.3-3.1）web.xml文件的schema头部声明

Java EE 7 XML schema，命名空间是 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，命名空间是 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，命名空间是 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, 命名空间是 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，这个版本的web.xml文件太老了，强烈建议升级

<!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头部声明

原文地址：http://blog.51cto.com/12348890/2092129