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我使用 DownloadManager 从 URL 下载 xml 文件。然后我使用线程等待 2 秒以完成将文件保存到 sd 卡。

我想要一个活动圈，如图所示。实现这一点的最简单方法是什么？我需要实施一个AsyncTask吗？

我要下载并等待的代码：

               //Download XML file from URL 
                DownloadManager.Request request = new DownloadManager.Request(Uri.parse(URL));
                request.setTitle("Download von "+Name+".xml");

                // in order for this if to run, you must use the android 3.2 to compile your app
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
                    request.allowScanningByMediaScanner();
                    request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
                }

                request.setDestinationInExternalPublicDir(FileSeperator+"XML"+FileSeperator, Name + FileExtension);

                // get download service and enqueue file
                DownloadManager manager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
                manager.enqueue(request);  

                File file = new File(Environment.getExternalStorageDirectory()+ FileSeperator 
                        +"XML"+FileSeperator+ Name + FileExtension);

                System.out.println("File existiert "+file.exists());

                //insert delay after download to finish save progress before starting to parse the xml
                try {
                    Thread.sleep(2000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

更新 这是我实现的 AsyncTask

private class DownloadFile extends AsyncTask<String, Integer, String> {
    @Override
    protected String doInBackground(String... sUrl) {
        try {
            //Download XML file from URL 
        DownloadManager.Request request = new DownloadManager.Request(Uri.parse(URL));
        request.setTitle("Download von "+Name+".xml");

        // in order for this if to run, you must use the android 3.2 to compile your app
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
            request.allowScanningByMediaScanner();
            request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
        }

        request.setDestinationInExternalPublicDir(FileSeperator+"XML"+FileSeperator, Name + FileExtension);

        // get download service and enqueue file
        DownloadManager manager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
        manager.enqueue(request);  

        File file = new File(Environment.getExternalStorageDirectory()+ FileSeperator 
                +"XML"+FileSeperator+ Name + FileExtension);

        System.out.println("File existiert "+file.exists());

        //insert delay after download to finish save progress before starting to parse the xml
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        } catch (Exception e) {
        }
        return null;
    }
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pDialog.show();
    }
    protected void onPostExecute() {
        super.onPreExecute();
        pDialog.dismiss();
    }
    @Override
    protected void onProgressUpdate(Integer... progress) {
        super.onProgressUpdate(progress);
    }
}

我这样称呼它：

    // instantiate it within the onCreate method
        pDialog = new ProgressDialog(CreateProject.this);
        pDialog.setMessage("Lädt...");
        pDialog.setIndeterminate(true);

        // execute this when the downloader must be fired
        DownloadFile downloadFile = new DownloadFile();
        downloadFile.execute();
4

3 回答 3

2

我认为是的，你应该用AsynsTask类来实现它，它清晰、快速、简单。你可以在这里阅读一个简短的教程AsyncTask

于 2012-10-02T12:38:45.170 回答
1

您可以使用 asynctask onPreExecute() 很好地满足您的要求，显示您的进度对话框在 doInBackground() 中执行您的过程，然后 onPostExecture 关闭对话框并显示您的结果。

于 2012-10-02T12:31:23.920 回答
0

只需在子类 onPostExecute 中调用 super.onPostExecute() 而不是 super.onPreExecute() ，否则将无法正常工作

于 2013-01-03T18:36:40.477 回答