Java 读取本地文件，并返回给前端

十分简单，不过多赘述，看代码。

	@GetMapping("/downloadTemplate")
	public void downloadExcelFile(HttpServletResponse response) throws IOException {
        // 使用系统属性获取正确的路径分隔符
		String separator = File.separator;
        // 文件的存放路径
		String path = System.getProperty("user.home") + separator + "Desktop" + separator + "testImport.xlsx";
		// 读到流中
		InputStream is = new FileInputStream(path);
		BufferedInputStream inputStream = new BufferedInputStream(is);
		response.reset();
		response.setContentType("application/octet-stream");
		String filename = new File(path).getName();
		response.addHeader("Content-Disposition", "attachment; filename=" + URLEncoder.encode(filename, "UTF-8"));
		ServletOutputStream outputStream = response.getOutputStream();
		byte[] b = new byte[1024];
		int len;
        //从输入流中读取一定数量的字节，并将其存储在缓冲区字节数组中，读到末尾返回-1
		while ((len = inputStream.read(b)) > 0) {
			outputStream.write(b, 0, len);
		}
		inputStream.close();
		is.close();
	}