[Spring实战系列]（19）Servlet不同版本之间的区别

1.   2.3版本

<!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>

The content of element type "web-app" must match "(icon?,display-name?,description?,distributable?,
context-param*,filter*,filter-mapping*,listener*,servlet*,servlet-mapping*,session-config?,mime-mapping*,
welcome-file-list?,error-page*,taglib*,resource-env-ref*,resource-ref*,security-constraint*,
login-config?,security-role*,env-entry*,ejb-ref*,ejb-local-ref*)". eoso/WebRoot/WEB-INF

<!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>Archetype Created Web Application</display-name>
<!--servlet-->
<servlet>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>com.qunar.fresh.servlet.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/login.do</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>AccessServlet</servlet-name>
<servlet-class>com.qunar.fresh.servlet.AccessServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>AccessServlet</servlet-name>
<url-pattern>/a/*</url-pattern>
</servlet-mapping>
</web-app>

<!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>Archetype Created Web Application</display-name>
<!--servlet-->
<servlet>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>com.qunar.fresh.servlet.LoginServlet</servlet-class>
</servlet>
<servlet>
<servlet-name>AccessServlet</servlet-name>
<servlet-class>com.qunar.fresh.servlet.AccessServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/login.do</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>AccessServlet</servlet-name>
<url-pattern>/a/*</url-pattern>
</servlet-mapping>
</web-app>

2.  2.4版本

<web-app 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">[/code] 
2.4以上版本即可解决上面问题。

但是2.4及以下版本会有一个问题：（多个url不能映射到同一个servlet）

<servlet-mapping>
<servlet-name>mvc-dispatcher</servlet-name>
<url-pattern>/index</url-pattern>
<url-pattern>/login</url-pattern>
</servlet-mapping>



3.  2.5版本
<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">


2.5以上版本即可解决多个url不能映射到同一个servlet的问题。

4. 3.0版本
<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>
<display-name>Servlet 3.0 Web Application</display-name>
</web-app>


Servlet3.0随J2EE6一起发布，web.xml配置文件中包含： 默认页配置、session超时配置和错误提示页配置。

<?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" >

<session-config>
<session-timeout>30</session-timeout>
</session-config>

<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>

<error-page>
<error-code>404</error-code>
<location>/404.jsp</location>
</error-page>

<error-page>
<error-code>500</error-code>
<location>/500.jsp</location>
</error-page>

</web-app>