为什么 getUriForDownloadedFile() returns null

Question

我正在通过 DownloadManager 下载图片 (API 28)。图片下载成功并显示在ImageView中。我想找出文件名。但是 getUriForDownloadedFile() return 为空。为什么？

private void dowloadfile() {
    Uri uri = Uri.parse(editText.getText().toString());
    DownloadManager.Request request = new DownloadManager.Request(uri);
    request.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_WIFI | DownloadManager.Request.NETWORK_MOBILE);
    request.setAllowedOverRoaming(false);
    request.setVisibleInDownloadsUi(true);
    request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "picture." + extension);

    registerReceiver(onComplete, new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE));

    refid = downloadManager.enqueue(request);
    Uri u = downloadManager.getUriForDownloadedFile(refid);
}

Answer 1

入队后，下载是一个异步操作，uri可能会在下载完成后分配，你需要监听你的接收器并传递id来获取uri

为什么 getUriForDownloadedFile() returns null

Why getUriForDownloadedFile() returns null

java

android

android-download-manager