POI 微信小程序的wx.downloadFile API下载文件-优快云博客

本文链接：https://blog.youkuaiyun.com/END_Loving/article/details/107927102

本文介绍了一种在Java环境中生成Excel报表的方法，并提供了文件下载的实现细节。通过使用UUID生成唯一文件名，确保了文件的唯一性。文章还涵盖了如何设置HTTP响应头以允许用户下载文件，以及如何在下载完成后清理临时文件。

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excel报表生成和下载

生成文件并返回下载路径路径

生成文件接口（业务数据没写进去下方是文件处理代码）

String uuid = UUID.randomUUID().toString().replace("-", "");
	String fileName = uuid + ".xls";
	String root = FileUtill.getResourceBasePath();
	try {
		String path = root + File.separator + "manhours" + File.separator + fileName;
		File file = new File(path);
		if (!file.getParentFile().exists()) {
			file.getParentFile().mkdirs();
		}
		FileOutputStream fileOut = new FileOutputStream(path);
		workBook.write(fileOut);
		fileOut.close();
		String pPath = request.getContextPath() + "/manhours/file/" + uuid;
		return result = JtsResultUtil.success(pPath);
	} catch (Exception e) {
		result = JtsResultUtil.success(e.getMessage());
	} finally {
		workBook.close();
}

下载文件接口

请求上一个接口返回的文件下载路径
（注意文件被下载后会被删除，如果不需要请自行删除finally中判断部分的代码）

@RequestMapping(value = "/file/{fileName}")
public void file(HttpServletRequest request, HttpServletResponse response, @PathVariable("fileName") String fileName) throws IOException, Exception {
	InputStream pInputStream = null;
	OutputStream os = response.getOutputStream();
	// 设置相关格式
	response.setContentType("application/force-download");
	// 设置下载后的文件名以及header
	String fileNameAlias = "月工时表.xls";
	fileNameAlias = URLEncoder.encode(fileNameAlias, "utf-8");
	response.setContentType("application/vnd.ms-excel");
	response.addHeader("Content-disposition", "attachment;fileName=" + fileNameAlias);
	String rootPath = FileUtill.getResourceBasePath();
	String filePath = rootPath + File.separator + "manhours" + File.separator + fileName + ".xls";
	File file = new File(filePath);
	try {
		pInputStream = new FileInputStream(file);
		int bufferSize = 1024;
		byte[] buffer = new byte[bufferSize];
		int len = 0;
		while ((len = pInputStream.read(buffer, 0, bufferSize)) != -1) {
			os.write(buffer, 0, len);
		}
	} catch (IOException e) {
		e.printStackTrace();
	} finally {
		if (pInputStream != null) {
			pInputStream.close();
			if (file != null && file.exists()) {
				file.delete();
			}
		}
		os.flush();
		os.close();
	}
}