使用commons-io对文件的上传下载

这是一个已经封装好了的commons-io操作文件上传下载的工具类。使用只需要改变上传，下载的路径即可；

public class CommonsUtil {
        
	private static final int MEMORY_THR = 1024*1024*3;
	private static final int FILE_MAX = 1024*1024*200;
	private static final int MAX = 1024*1024*1000;
	private static final String UPLOAD_PATH = "upload";
	  //private static final ;
//--------------------上传文件---------------------------------------
	public static Map<String, Object> upLoad(HttpServletRequest request){
		//保存文件，同时接收表单中的其他信息；
		//配置文件上传信息
		DiskFileItemFactory factory = new DiskFileItemFactory();
		//设置内存临界值，超过范围，存入临时目录中；
		factory.setSizeThreshold(MEMORY_THR);
		
		//设置超出范围的临时目录；
		factory.setRepository(new File(System.getProperty("java.io.tmpdir")));
		
		ServletFileUpload upload = new ServletFileUpload(factory);
		
		//配置上传文件参数；
		upload.setFileSizeMax(FILE_MAX);
		upload.setSizeMax(MAX);
		upload.setHeaderEncoding("utf-8");
		
		//创建对象，接收表单其它数据；
		HashMap<String, Object> map = new HashMap<String, Object>();
		
		//拼接一下上传文件的保存路径；
		String uppath = request.getServletContext().getRealPath("")+File.separator+UPLOAD_PATH;
		
		//判断上传的是File，还是text;
		
		//解析传过来的参数;
		try {
			 List  items = upload.parseRequest(request);
			 Iterator it = items.iterator();
			 while(it.hasNext()){
				 FileItem item = (FileItem) it.next();
				 
				 if(item.isFormField()){
					 String value = item.getString("utf-8");
					 String name = item.getFieldName();
					 map.put(name, value);
					// System.out.println("name==>"+name+"value==>"+value);
				 }else{
					 //操作文件
					 String type = item.getFieldName();
					 String filename = new File(item.getName()).getName();
					 String getname = item.getName();
					 //将上传的文件，文件名保存到数据库中：
					// System.out.println("type==>"+type+"value==>"+filename+"getname==>"+getname);

					 map.put(type, filename);
					 //指定存放位置；
					 String savepath = uppath+"/"+filename;
					 File storfile = new File(savepath);
					 
					  //将文件保存到服务器磁盘中
					 item.write(storfile);
				 }
			 }
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		return null;
	} 
//---------------------获取上传的所有文件----------------------------------------------------------	
	public static void display(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException{
		//上传文件目录
				String uploadPath = request.getServletContext().getRealPath("/upload");
				//定义 集合 存放文件名称
				/*Map<String, String> fileNameMap = new HashMap<String, String>();*/
				List<String> list = new ArrayList<String>();
		 		//根据路径生成 文件
				File file =	new File(uploadPath);
				//调用方法
				judgeFile(file, list);
				request.setAttribute("comlist", list);
				request.getRequestDispatcher("../downupload.jsp").forward(request, response);
	
	}
	
//------------------递归遍历文件--------------------------------------	
	public static void judgeFile(File file,List list){
		
		if(!file.isFile()){
			File[] files= file.listFiles();
			for (File f : files) {
				judgeFile(f, list);
			}
		}else{
			//map.put(file.getName(), file.getName());
			list.add(file.getName());
		}
	}
	
//-----------------------下载文件------------------------------------------------	
	public static void downloadFile(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException{
		//获取下载文件名称
		String fileName = req.getParameter("filename");
		fileName = new String(fileName.getBytes("iso-8859-1"),"utf-8");
		//确定下载的目录文件夹
		String fileSavePath = req.getServletContext().getRealPath("/upload");
		//拼接下载的文件路径
		File file = new File(fileSavePath+"\\"+fileName);
		
		if(!file.exists()){
			req.setAttribute("message", "下载的文件不存在....");
			req.getRequestDispatcher("../downupload.jsp").forward(req, res);
			return;
		}
		//如果文件存在 则下载
		res.setHeader("content-disposition","attachment; filename="+URLEncoder.encode(fileName, "utf-8"));
		//已文件流的方式 进行下载操作
		FileInputStream in = new FileInputStream(file);
		OutputStream out =	res.getOutputStream();
		byte buffer[] = new byte[1024];
		int lne = 0;
		//循环读取
		while((lne=in.read(buffer))>0){
			out.write(buffer, 0, lne);
		}
		in.close();
		out.close();
	}
}

servlet服务层只需要调用相对应的上传下载的方法即可:

public class CommonsFlie extends BaseServlet {
       
	
	public void comupLoad(HttpServletRequest request, HttpServletResponse response) throws IOException{
	          
		CommonsUtil.upLoad(request);
		response.sendRedirect("../downupload.jsp");
	}	
	
	public void comdisplay(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException{
        
		CommonsUtil.display(request, response);
		
	}
	
	public void comdownLoad(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException{
        
		CommonsUtil.downloadFile(request, response);
		
	}

前台页面发送请求：

 <h3>commons-io-方式上传文件</h3>
        <form method="POST" ENCTYPE="multipart/form-data" action="servlet/CommonsFlie?op=comupLoad">
          <input type="file" name="upfile"/> 
	      <span>昵称：</span>  <input type="text" name="username"/>   
	       <span>年龄：</span>  <input type="text" name="userage"/>   
	      <input type="submit" value="上传">  
       </form>
       
       <a href="servlet/CommonsFlie?op=comdisplay">显示文件列表</a><br>
       <c:forEach items="${comlist }" var="item">
      <a href="servlet/CommonsFlie?op=comdownLoad&filename=${item }"> <span>下载：${item }</span></a><br>
      
     </c:forEach>