服务器传输图片到客户端，有时候是直接下载，有时候是类似src='请求路径'

其主要区别在于

res.setContentType("img/jpg");
			res.setHeader("Content-Disposition", "attachment;filename="+fileName);

加了这两行之后就是下载 一个是格式，一个是文件名字

另外附上下载图片代码:

@ResponseBody
	@RequestMapping(value = "/downloadFile", method = { RequestMethod.GET, RequestMethod.POST })
	public void downloadFile(HttpServletRequest request, HttpServletResponse res) {
		logger.info("downloadFile...");
		String fileName = request.getParameter("fileName");
		File file = new File(fileUploadPath + fileName);
		if (!file.exists()) {
			logger.error("resource file not exists.");
		}
		BufferedInputStream bis = null;
		BufferedOutputStream bos = null;
		try {
			res.setContentType("img/jpg");
			res.setHeader("Content-Disposition", "attachment;filename="+fileName);
			bis = new BufferedInputStream(new FileInputStream(file));
			bos = new BufferedOutputStream(res.getOutputStream());
			byte[] bys = new byte[1024];
			int len = 0;
			while ((len = bis.read(bys)) != -1) {
				bos.write(bys, 0, len);
			}
			logger.info("downloadComplete...");
		} catch (IOException e) {
			e.printStackTrace();
			logger.error("downloadError", e);
		} finally {
			try {
				bos.close();
				bis.close();
			} catch (IOException e) {
			}
		}
	}