实现上传和下载文件的例子

求一个实现上传和下载文件的例子
最好下载的比较详细，小弟新手，感激不尽
邮箱：sun910601@sina.com
------解决方案--------------------

    <?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">  

        <filter>  

            <filter-name>struts2</filter-name>  

            <filter-class>  

                org.apache.struts2.dispatcher.FilterDispatcher  

            </filter-class>  

        </filter>  

        <filter-mapping>  

            <filter-name>struts2</filter-name>  

            <url-pattern>*.action</url-pattern>  

        </filter-mapping>  

        <welcome-file-list>  

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

        </welcome-file-list>  

    </web-app>  

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

<!DOCTYPE struts PUBLIC  

    "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"  

    "http://struts.apache.org/dtds/struts-2.0.dtd">  

<struts>  

    <constant name="struts.devMode" value="false" />  

    <!-- 改变struts2默认为2M的上传文件大小限制 -->  

    <constant name="struts.multipart.maxSize" value="10240000"/>  

    <package name="upload" extends="struts-default">  

        <action name="uploadFile" class="com.labci.struts2.action.UploadFileAction">  

            <param name="savePath">/upload</param>  

            <param name="allowTypes">text/plain,text/xml,text/html,image/gif,image/png,image/jpeg,image/jpg,image/bmp</param>  

            <result name="success">index.jsp</result>  

            <result name="input">index.jsp</result>  

        </action>  

        <action name="downloadFile" class="com.labci.struts2.action.DownloadFileAction">  

            <param name="savePath">/upload</param>  

            <result name="success">index.jsp</result>  

        </action>  

    </package>  

</struts>  

    /** 

     * Struts2Test 

     * 文件下载的Action 

     */  

    package com.labci.struts2.action;  

    import java.io.FileInputStream;  

    import java.io.InputStream;  

    import java.io.OutputStream;  

    import javax.servlet.http.HttpServletRequest;  

    import javax.servlet.http.HttpServletResponse;  

    import org.apache.struts2.interceptor.ServletRequestAware;  

    import org.apache.struts2.interceptor.ServletResponseAware;  

    import com.opensymphony.xwork2.ActionSupport;