springboot 下載excle文件

paradrop.xlsx 存在 src/main/resource/paradrop.xlsx

@RequestMapping(value = "/downloadExcel")
    public void downloadExcel(HttpServletResponse response, HttpServletRequest request) throws IOException {
        String fileName = "paradrop.xlsx";
        InputStream inputStream = Thread.currentThread().getContextClassLoader().getResourceAsStream(fileName);
        //強制下載不打開
        response.setContentType("application/binary;charset=ISO8859-1");
        OutputStream out = response.getOutputStream();
        //使用URLEncoder來防止文件名亂碼或者讀取錯誤
        response.setHeader("Content-Disposition", "attachment; filename="+ URLEncoder.encode(fileName, "UTF-8"));
        int b = 0;
        byte[] buffer = new byte[1000000];
        while (b != -1) {
            b = inputStream.read(buffer);
            if(b!=-1) out.write(buffer, 0, b);
        }
        inputStream.close();
        out.close();
        out.flush();

    }