flutter_inappwebview和flutter_downloader - 不确定我做错了什么？

Question

前端信息：

Language: Flutter/Dart
Flutter Packages: flutter_inappwebview, flutter_downloader

我正在使用Flutter为Android构建一个移动应用程序。该应用程序的一个功能是能够下载与PDF文件相关联的链接。这些文件位于应用程序已在访问的服务器上。用户已通过应用程序登录，因此已建立身份验证。当点击一个有PDF的URL时，它会执行重定向，然后返回并下载主页(index.php(。我不知道这是怎么发生的，但我有想法。

1. 我需要在当前的网络视图中进行下载(就像在同一个会话和窗口中一样(
2. 禁用URL重定向
3. 弄清楚为什么链接被重定向以进行身份验证(假设它重定向到主页(

如有任何想法或帮助，我们将不胜感激。很乐意提供更多信息。

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;
},

日志记录：

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中进行了身份验证，但flutter下载程序似乎在单独的上下文中运行，因此用户没有经过身份验证。

为了维护用户会话，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函数，该函数从CookieManager检索cookie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事件侦听器中调用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cookie传递到onDownloadStart事件侦听器中FlutterDownloader的头部：

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