java文件下载

public void downloadAttachment(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response)
			throws TSDBException, IOException {
		// 附件Id
		Long fileId = new Long(request.getParameter("id"));
		// 根据id取得相应的附件
		PicAttachment picAttachment = getAttachment(fileId);
		String realName = picAttachment.getRealFilename();

		byte[] downloadFile = picAttachment.getUploadFile();
		response.reset();
		// 设置为下载application/x-download
		response.setContentType("application/x-download");
		/*
		 * 这个属性设置的是下载工具下载文件时显示的文件名,要想正确的显示中文文件名，我们需要对fileName再次编码
		 * 否则中文名文件将出现乱码，或无法下载的情况
		 */
		realName = URLEncoder.encode(realName, "utf-8");
		// 下载文件时，显示的文件名
		response.addHeader("Content-Disposition", "attachment;filename=" + realName);

		OutputStream output = response.getOutputStream();
		output.write(downloadFile);
		output.flush();
		output.close();
	}