WEB应用中的普通Java程序如何读取资源文件

<?xml version="1.0" encoding="UTF-8"?>
<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"> 
<servlet>
<servlet-name>ServletDemo1</servlet-name>
<servlet-class>cn.itcast.ServletDemo1</servlet-class>
</servlet>
<servlet>
<servlet-name>ServletDemo3</servlet-name>
<servlet-class>cn.itcast.ServletDemo3</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>ServletDemo1</servlet-name>
<url-pattern>/ServletDemo1</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>ServletDemo3</servlet-name>
<url-pattern>/servlet/ServletDemo3</url-pattern>
</servlet-mapping>

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