flutter_inappwebview 和 flutter_downloader - 不知道我做错了什么？

Question

前期资料：

Language: Flutter/Dart
Flutter Packages: flutter_inappwebview, flutter_downloader

我正在使用 Flutter 为 Android 构建移动应用程序时遇到问题。 该应用程序的一个 function 是能够下载与 PDF 文件关联的链接。 这些文件位于应用程序已经访问的服务器上。 用户已通过应用程序登录，因此已建立身份验证。 当单击具有 PDF 的 URL 时，它会执行重定向并返回并下载主页（index.php）。 我不知道这是如何发生的，但我有想法。

1. 我需要在当前的 webview 中进行下载（如在相同的 session 和窗口中）。
2. 禁用 URL 重定向。
3. 弄清楚为什么要重定向链接以进行身份验证（假设它正在重定向到主页）。

任何想法或帮助将不胜感激。 也很高兴提供更多信息。

在 main.dart 中：

onDownloadStart: (controller, url) async {
                print("onDownloadStart $url");
                final taskId = await FlutterDownloader.enqueue(
                  headers: {'My-Custom-Header': 'custom_value=564hgf34'},
                  url: url,
                  savedDir: (await getExternalStorageDirectory()).path,
                  showNotification: true, // show download progress in status bar (for Android)
                  openFileFromNotification: true, // click on notification to open downloaded file (for Android)
                );
                return taskId;
              },

记录：

I/flutter (28552): onDownloadStart https://hjhvtc.online/pluginfile.php/6723/mod_resource/content/1/Automotive%20industry%20jobs.pdf
W/WM-WorkSpec(28552): Backoff delay duration less than minimum value
D/DownloadWorker(28552): DownloadWorker{url=https://hjhvtc.online/pluginfile.php/6723/mod_resource/content/1/Automotive%20industry%20jobs.pdf,filename=null,savedDir=/storage/emulated/0/Android/data/com.coffeepaulconsulting.hjhvtconline/files,header={"My-Custom-Header": "custom_value=564hgf34"},isResume=false
D/DownloadWorker(28552): Update notification: {notificationId: 1, title: https://hjhvtc.online/pluginfile.php/6723/mod_resource/content/1/Automotive%20industry%20jobs.pdf, status: 2, progress: 0}
D/DownloadWorker(28552): Open connection to https://hjhvtc.online/pluginfile.php/6723/mod_resource/content/1/Automotive%20industry%20jobs.pdf
D/DownloadWorker(28552): Headers = {"My-Custom-Header": "custom_value=564hgf34"}
D/DownloadWorker(28552): Response with redirection code
D/DownloadWorker(28552): Location = https://hjhvtc.online/login/index.php
D/DownloadWorker(28552): New url: https://hjhvtc.online/login/index.php
D/DownloadWorker(28552): Open connection to https://hjhvtc.online/login/index.php
D/DownloadWorker(28552): Headers = {"My-Custom-Header": "custom_value=564hgf34"}
V/InputMethodManager(28552): b/117267690: Failed to get fallback IMM with expected displayId=197 actual IMM#displayId=0 view=com.pichillilorenzo.flutter_inappwebview.InAppWebView.InAppWebView{4592e22 VFEDHVCL. ......ID 0,0-1080,1997}
D/DownloadWorker(28552): Content-Type = text/html; charset=utf-8
D/DownloadWorker(28552): Content-Length = -1
D/DownloadWorker(28552): Charset = UTF-8
D/DownloadWorker(28552): Content-Disposition = null
D/DownloadWorker(28552): fileName = index.php
D/DownloadWorker(28552): Update too frequently!!!!, this should be dropped
D/DownloadWorker(28552): There's no application that can open the file /storage/emulated/0/Android/data/com.coffeepaulconsulting.hjhvtconline/files/index.php
D/DownloadWorker(28552): Update too frequently!!!!, but it is the final update, we should sleep a second to ensure the update call can be processed
D/DownloadWorker(28552): Update notification: {notificationId: 1, title: index.php, status: 3, progress: 100}
D/DownloadWorker(28552): File downloaded
I/WM-WorkerWrapper(28552): Worker result SUCCESS for Work [ id=633dd93d-99e3-46e2-937d-a4782d62a569, tags={ flutter_download_task, vn.hunghd.flutterdownloader.DownloadWorker } ]

Answer 1

经过几次尝试，我终于找到了解决方案。 DownloadWorker 被重定向到登录页面，因为尽管用户在 InAppWebView 中经过身份验证，但 flutter 下载器似乎在单独的上下文中运行，因此用户未经过身份验证。

为了维护用户 session，我创建了一个变量：

  // Store cookies to save user session for download
  String cookiesString = '';

然后，我创建了updateCookies function 从 CookieManager 检索CookieManager并更新cookiesString变量：

  Future<void> updateCookies(Uri url) async {
    List<Cookie> cookies = await CookieManager().getCookies(url: url);
    cookiesString = '';
    for (Cookie cookie in cookies) {
      cookiesString += '${cookie.name}=${cookie.value};';
    }
    print(cookiesString);
  }

然后，我在 InAppWebView 的onLoadStop事件监听器中调用updateCookies ：

onLoadStop: (controller, url) async {
    pullToRefreshController.endRefreshing();

    if (url != null) {
        await updateCookies(url);
    }

    setState(() {
        this.url = url.toString();
        urlController.text = this.url;
    });
},

最后，我将 cookies 传递给onDownloadStart事件监听器中 FlutterDownloader 的 headers：

                  await FlutterDownloader.enqueue(
                    headers: {
                      HttpHeaders.authorizationHeader: 'Basic ' +
                          authToken,
                      HttpHeaders.connectionHeader: 'keep-alive',
                      HttpHeaders.cookieHeader: cookiesString,
                    },