Java文件下载模块

	<td align='center' width="10%">
      <a href="${pageContext.request.contextPath}/queryAction.do?method=fileDownload&fileName=${mail.filename}">下载</a>
      	</td>                                   

	/** 
	 * 下载邮件附件
	 * @param mapping
	 * @param form
	 * @param request
	 * @param response
	 * @return ActionForward
	 */
	public ActionForward fileDownload(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) {
		String fileName = request.getParameter("fileName");//路径名
		String name=StringUtil.filenameOfPath(fileName);//文件名
		File file = null;
		FileInputStream fileInputStream = null;
		OutputStream outputStream;
		try {
			response.setCharacterEncoding("UTF-8");
			response.setHeader("Content-disposition", "attachment; filename=" + name);
			response.setContentType("application/octet-stream");
//			file = new File(Constants.TOMCAT_LOG_DIR + File.separator + fileName);
			file = new File(fileName);
			if (!file.exists()) {
				String msg = "文件 " + name + "不存在，请联系管理员！";
				if (log.isInfoEnabled()) log.info(msg);
				throw new Exception(msg);
			}
			
			if (log.isInfoEnabled()) log.info("准备文件 " + file.getAbsolutePath());
			fileInputStream = new FileInputStream(file);
			outputStream = response.getOutputStream();
			if (log.isInfoEnabled()) log.info("文件初始大小 " + file.length());
			byte[] buff = new byte[1024 * 5];
			int len;
			log.info("读取开始...");
			while ((len = fileInputStream.read(buff)) != -1) {
				outputStream.write(buff, 0, len);
			}
			outputStream.flush();
			outputStream.close();
			log.info("读取完成...");
		}
		catch (Exception e) {
			String msg = "文件" + name + " 下载失败，请联系管理员！";
			log.error(msg, e);
			request.setAttribute("message", e.getMessage());
			request.setAttribute("forward", "MailAction.do?method=mailboxList");
			return mapping.findForward("GlobalMsg");
		}
		finally {
			try {
				if (fileInputStream != null) fileInputStream.close();
			}
			catch (IOException e) {
				e.printStackTrace();
			}
		}
		return null;
	}

方法二：写到固定的地方：

	@RequestMapping( { "/queryAnddownloadImg" })
	@ResponseBody
	public HashMap<String, Object> queryAnddownloadImg(String path) {
		log.info("影像文件下载>>>>>>>>>>>>>>>>>>");
		HashMap<String, Object> result = new HashMap<String, Object>();
		String myfilePath = Constant.IMGFILEDIR;
		String Name = path.substring(path.indexOf("_")+1) ;
		System.out.println(Name);
			if (path.equals("")) {
				result.put("success",false);
				result.put("errMessage","你要下载的文件不存在，请确认！") ;
			} else {
				Tool tool = new Tool();
				File file = new File(myfilePath);
				if(!file.exists()){
					file.mkdirs();
				}
				try {
					File f = new File(path) ;
				    byte[] data = null;
				    FileImageInputStream input = new FileImageInputStream(f);
				    ByteArrayOutputStream output = new ByteArrayOutputStream();
				    byte[] buf = new byte[1024];
				    int numBytesRead = 0;
				    while ((numBytesRead = input.read(buf)) != -1) {
				        output.write(buf, 0, numBytesRead);
				    }
				    data = output.toByteArray();
				    output.close();
				    input.close();
				    FileImageOutputStream imageOutput = new FileImageOutputStream(
				    		  new File(myfilePath+File.separator+Name));
				    imageOutput.write(data, 0, data.length);
				    imageOutput.close();
				    System.out.println("Make Picture success,Please find image in " + myfilePath+File.separator+Name);
					result.put("success",true);
					result.put("message","下载文件成功！文件保存为【  " + myfilePath+File.separator+Name+"】") ;
				} catch (IOException e) {
					e.printStackTrace();
				}
				
			}
			return result;
	}