java通过url下载网络资源

场景：从网络上下载资源，来更新本地的资源，以xlsx文件为例

public static void main(String[] args) throws Exception {
        //下载地址
        String downURL = "*";
        // 地址
        URL url = new URL(downURL);
        // 打开地址
        HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
        // 获取流
        InputStream is = urlConnection.getInputStream();
        // 写入流
        Random random = new Random();
        //如果文件存在则替换/重写
        FileOutputStream fos = new FileOutputStream("**.xlsx");
        
        // 写入文件
        byte[] buffer = new byte[1024];
        int len;
        while ((len = is.read(buffer)) != -1) {
            fos.write(buffer, 0, len);
        }

        // 关闭流
        fos.close();
        is.close();
        urlConnection.disconnect(); // 断开连接
    }