使用struts2实现上传下载功能（附代码）。类似于ftp服务器。不止局限于本机的上传下载，其他机器也可使用此功能，服务器似的功能
一、截图展示功能概要：
（1）主界面：
（2）单击浏览后：
（3）选择文件，单击提交，进入文件展示界面（下载功能界面）
（4）单击“下载”按钮，
（5）单击保存进行保存，成功保存
功能展示完毕。
二、代码实现：
1.目录结构
2.struts2.xml
<?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>
<!-- struts的开发模式，设置为true,改变此文档中的配置不用重启tomcat -->
<constant name="struts.devMode" value="true"></constant>
<package name="default" extends="struts-default">
<default-action-ref name="index" />
<action name="index"><result>/jsp/upload.jsp</result></action>
</package>
<package name="uploadAnddownload" extends="struts-default" namespace="/user">
<result-types>
<!-- 用于处理下载文件,提示对话框点击取消时报出异常问题 -->
<result-type name="streamx" class="com.sunspoter.lib.web.struts2.dispatcher.StreamResultX"></result-type>
</result-types>
<action name="upload" class="com.upload.action.UploadAction" method="upload">
<result name="input">/jsp/listfile.jsp</result>
<result name="success" type="redirectAction">queryAllFile</result>
</action>
<action name="queryAllFile" class="com.upload.action.QueryAllFileAction" method="queryAllFile">
<result name="input">/jsp/listfile.jsp</result>
</action>
<action name="download" class="com.upload.action.DownloadAction" method="download">
<result type="streamx">
<!-- 文件类型 —— application/octet-stream 表示无限制 -->
<param name="contentType">application/octet-stream;charset=ISO8859-1</param>
<!-- 流对象名 —— 去找Action中的getInputStream方法 -->
<param name="inputName">inputStream</param>
<!-- 文件名 —— 将调用该Action中的getDownloadFileName方法 -->
<param name="contentDisposition">attachment;fileName="${downloadFileName}"</param>
<!-- <param name="bufferSize">4096</param> -->
</result>
</action>
</package>
</struts>
3.web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" version="2.4">
<filter>
<filter-name>struts2</filter-name>
<filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>struts2</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>
4.index.jsp
<% response.sendRedirect("index.action"); %>
5.upload.jsp
<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%>
<%@ taglib prefix="s" uri="/struts-tags" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'upload.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
<script type="text/javascript">
/* function showPhoto(){
document.getElementById("showPhoto").src=document.getElementById("photo").value;
} */
</script>
</head>
<body>
<form action="user/upload.action" method="post" enctype="multipart/form-data">
<input type="file" name="photo" id="photo" onchange="showPhoto()"/>
<input type="submit" value="提交"/>
</form>
<br>
<s:a action="queryAllFile.action" namespace="/user">
进入下载页面
</s:a>
<!-- <div>
<img id="showPhoto" src="/upload/photo.jpg" style="width:160px;height:120px;"/>
</div> -->
</body>
</html>
6.listfile.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'listfile.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
文件列表<br>
<table border="1">
<s:iterator id="file" value="fileNameMap">
<tr>
<td>${file.value}</td>
<td>
<s:a action="download.action" namespace="/user">
<s:param name="fileName">${file.value}</s:param> 下载
</s:a>
</td>
</tr>
</s:iterator>
</table>
</body>
</html>
7.UploadAction
package com.upload.action;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import org.apache.commons.io.IOUtils;
import org.apache.struts2.ServletActionContext;
import com.opensymphony.xwork2.ActionSupport;
public class UploadAction extends ActionSupport{
private static final long serialVersionUID = 1L;
private File photo;
private String photoFileName;
private String photoContentType;
private String savePath;
public String upload(){
System.out.println("**********************upload*********************");
//判断目录是否存在，不存在的话要新建
File file = new File(getSavePath());
if(!file.exists() && !file.isDirectory()){
System.out.println(savePath+"目录不存在，需要重建");
file.mkdir();
}
if(photo!=null){
try {
InputStream is = new FileInputStream(getPhoto());
OutputStream os = new FileOutputStream(getSavePath()+"//"+getPhotoFileName());
IOUtils.copy(is, os);
os.flush();
IOUtils.closeQuietly(is);
IOUtils.closeQuietly(os);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return "success";
}
public File getPhoto() {
return photo;
}
public void setPhoto(File photo) {
this.photo = photo;
}
public String getPhotoFileName() {
return photoFileName;
}
public void setPhotoFileName(String photoFileName) {
this.photoFileName = photoFileName;
}
public String getPhotoContentType() {
return photoContentType;
}
public void setPhotoContentType(String photoContentType) {
this.photoContentType = photoContentType;
}
public String getSavePath() {
return ServletActionContext.getServletContext().getRealPath("/upload");
}
public void setSavePath(String savePath) {
this.savePath = savePath;
}
}
8.DownloadAction
package com.upload.action;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import org.apache.struts2.ServletActionContext;
import com.opensymphony.xwork2.ActionSupport;
public class DownloadAction extends ActionSupport{
private static final long serialVersionUID = 1L;
private String fileName;//要下载的文件名
private InputStream inputStream;
public String download() throws Exception {
System.out.println("********************download****************");
System.out.println("getFileName="+getFileName());
inputStream = ServletActionContext.getServletContext().getResourceAsStream("/upload/" + getFileName());
System.out.println("inputStream="+inputStream);
return SUCCESS;
}
//为解决文件名字乱码。struts2.xml中读取的是downloadFileName而不是fileName
public String getDownloadFileName() throws UnsupportedEncodingException {
String downloadFileName = new String(fileName.getBytes(), "ISO8859-1");
return downloadFileName;
}
public String getFileName() {
return fileName;
}
public void setFileName(String fileName) throws UnsupportedEncodingException {
//this.fileName = fileName;
this.fileName = new String(fileName.getBytes("ISO-8859-1"),"UTF-8");
}
public InputStream getInputStream() {
return inputStream;
}
public void setInputStream(InputStream inputStream) {
this.inputStream = inputStream;
}
}
9.QueryAllFileAction
package com.upload.action;
import java.io.File;
import java.util.HashMap;
import java.util.Map;
import org.apache.struts2.ServletActionContext;
import com.opensymphony.xwork2.ActionSupport;
public class QueryAllFileAction extends ActionSupport{
/**
*
*/
private static final long serialVersionUID = 1L;
private Map<String,String> fileNameMap;
public String queryAllFile(){
System.out.println("******************queryAllFile******************");
//获取上传文件的目录
String filePath = ServletActionContext.getServletContext().getRealPath("/upload");
//存储要下载的文件名
fileNameMap = new HashMap<String,String>();
//递归遍历filePath下目录下的所有文件和目录，将文件的文件名存储到map集合中
listFile(new File(filePath),fileNameMap);
System.out.println("fileNameMap="+fileNameMap);
return "input";
}
//file即代表一个文件，也代表一个文件目录;map存储文件名的集合。递归遍历指定目录下的所有文件
private void listFile(File file, Map<String, String> map) {
//如果file代表的不是一个文件，而是一个目录
if(!file.isFile()){
//列出该目录下的所有文件和目录
File files[] = file.listFiles();
for(File f : files){
//递归
listFile(f,map);
}
}else{
map.put(file.getName(), file.getName());
}
}
public Map<String, String> getFileNameMap() {
return fileNameMap;
}
public void setFileNameMap(Map<String, String> fileNameMap) {
this.fileNameMap = fileNameMap;
}
}
三、小小心得
（1） 做上传功能之前一直纠结：文件是怎么传输到后台的，经过几天的寻找各种资源。明白前台<form action="user/upload.action" method="post" enctype="multipart/form-data">中<input type="file" name="photo">经过jsp解析（enctype="multipart/form-data"是允许将type=file的input解析成流的形式）。后台action中属性：
private File photo;
private String photoFileName;
private String photoContentType;
与jsp中<input type="file" name="photo">对应
（2）下载功能中其实重要的就是struts中的配置，将后台传输过来的文件形成的流和文件名字进行配置，输出到jsp前台
需要注意的是：<param name="contentDisposition">attachment;fileName="${downloadFileName}"</param> 是为了解决中文乱码。附件代码以及上边的粘贴代码中都有注释我就不多解释；
（3）其余的我就不多说了。只要对struts2的基本流程了解。把下边链接中的代码copy到自己的电脑上研究运行。我相信肯定能更加清楚其中原理。
四、完整项目包链接
http://download.csdn.net/detail/zhaoxiaoyueyue/9482979