2：控制器程式碼：

String filename = map.get("name").toString();
		response.setContentType("text/html;charset=utf-8");
		request.setCharacterEncoding("UTF-8");
		// 獲取路徑
		String ctxPath = request.getSession().getServletContext().getRealPath("/")+ "\\" + "upload\\";
		String downLoadPath = ctxPath + filename;
		// 建立file物件
		File file = new File(downLoadPath);
		if (file.exists()) {
			 // 寫明要下載的檔案的大小
			 response.setContentLength((int) file.length());
			 response.setContentType("application/x-msdownload"); 
	         response.setHeader("Content-Disposition", "attachment; filename=" + java.net.URLEncoder.encode(file.getName(),"UTF-8")); 
		}else{
			response.setStatus(404);
		}
         // 讀出檔案到i/o流
		FileInputStream fis = new FileInputStream(file);
		BufferedInputStream buff = new BufferedInputStream(fis);
		byte[] b = new byte[1024];// 相當於我們的快取
		long k = 0;// 該值用於計算當前實際下載了多少位元組
		// 從response物件中得到輸出流,準備下載
		OutputStream myout = response.getOutputStream();
		// 開始迴圈下載
		while (k < file.length()) {
			int j = buff.read(b, 0, 1024);
			k += j;
			// 將b中的資料寫到客戶端的記憶體
			myout.write(b, 0, j);
		}
		// 將寫入到客戶端的記憶體的資料,重新整理到磁碟
		myout.flush();
		logger.debug("upload over");
		return null;
 

//下載
		function f_download(name){
			$("#name").val(name);
			var form = $("#download");
			form.attr("action","BsthJdJypxjlb/download.do");
			form.submit();
		}