<?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">    <!-- Define servlets that are included in the web application -->    <servlet>        <servlet-name>jack</servlet-name>        <servlet-class>sample.Jack</servlet-class>        <load-on-startup>1</load-on-startup>    </servlet>    <servlet>        <servlet-name>dog</servlet-name>        <servlet-class>sample.Dog</servlet-class>        <load-on-startup>2</load-on-startup>    </servlet>        <servlet-mapping>        <servlet-name>jack</servlet-name>        <url-pattern>/abc/*</url-pattern> <!-- 目录匹配 -->    </servlet-mapping>    <servlet-mapping>        <servlet-name>dog</servlet-name>        <url-pattern>/abc/3</url-pattern> <!-- 绝对匹配 -->    </servlet-mapping>    <servlet-mapping>        <servlet-name>dog</servlet-name>        <url-pattern>*.do</url-pattern> <!-- 扩展名匹配 -->    </servlet-mapping> <!-- 容器优先查找绝对匹配，然后依次是目录匹配、扩展名匹配，如果有冲突总是取最特定的匹配，也就是路径更长长的 -->    <!-- 启动容器就加载 servlet 不是默认行为！！！原因是!@$@$@$@%#$（自己想） -->    <error-page>        <!-- Throwable 是所有异常与错误的父类 -->        <exception-type>java.lang.Throwable</exception-type>        <location>/WEB-INF/jsp/exception/common-exception.jsp</location>    </error-page>    <error-page>        <error-code>404</error-code>        <location>/WEB-INF/jsp/exception/404-exception.jsp</location>    </error-page>    <welcome-file-list>        <welcome-file>index.html</welcome-file>        <welcome-file>abc/3</welcome-file>        <welcome-file>index.jsp</welcome-file> <!-- 与容器匹配规则不相同，文件名前不能放斜线！ -->        <!-- 每个目录可能有各自的 index.html ！-->        <!-- 容器先查 servlet 映射，没有才会找欢迎文件 -->    </welcome-file-list>    </web-app>