一.参考: 1.Android WebView 上传文件支持全解析 https://cloud.tencent.com/developer/article/1035050
2.Solutions for uploading files from Android WebView https://programmer.group/solutions-for-uploading-files-from-android-webview.html
3.File Upload in WebView https://stackoverflow.com/questions/5907369/file-upload-in-webview
3+Android webview支持H5页面通过js实现文件上传、图片上传 https://blog.csdn.net/Wang_WY/article/details/89183168
4.Android webview: download files like browsers do https://stackoverflow.com/questions/33434532/android-webview-download-files-like-browsers-do
5.Android WebView 支持文件下载的几种方式 https://www.jianshu.com/p/6e38e1ef203a
6.带你解决 WebView 里的常见问题 https://www.jianshu.com/p/fea5e829b30a
