InAppWebView(
  initialUrl: _url,
  onReceivedServerTrustAuthRequest: (controller, challenge) async {
      //解决 handshake failed问题
      return ServerTrustAuthResponse(
          action: ServerTrustAuthResponseAction.PROCEED);
    onLoadStop: (InAppWebViewController controller, String url) {
        loadingDismiss();
        print("网页 onLoadStop--》");
参考 https://stackoverflow.com/questions/62038787/fluttere-webview-handshake-failed