android - 进度条的使用

Question

我创建了一个应用程序，其中有 5 个按钮用于流式传输 5 个不同的直播频道。除了 5 个按钮，我还有一个进度条（环）。我正在使用进度条，因为视频需要时间来加载。我在 AsyncTask 的 onBackground() 中编写了主要代码，它返回一些在按钮的单击事件中调用的值。由于所有 5 个按钮都分配了不同的 url，我如何为所有 5 个按钮使用相同的 onBackground()？在这种情况下该怎么办？谁能给我一个很好的例子。

Answer 1

onBackground()是 AsyncTask 的一部分。它与按钮或其他 UI 元素没有任何共同之处。如果您想重用代码，只需将您的 UI 作为参数传递给 AsyncTask 构造函数，然后在需要时使用它。

Answer 2

Video Path

私有静态字符串 file_url = "url";

  in your activity

新的 DownloadFileFromURL().execute(file_url);

@Override
protected Dialog onCreateDialog(int id) {
    switch (id) {
    case progress_bar_type: // we set this to 0
        pDialog = new ProgressDialog(this);
        pDialog.setMessage("Downloading file. Please wait...");
        pDialog.setIndeterminate(false);
        pDialog.setMax(100);
        pDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
        pDialog.setCancelable(true);
        pDialog.show();
        return pDialog;
    default:
        return null;
    }
}

Background Async Task to download file



/**
     * Background Async Task to download file
     * */
    class DownloadFileFromURL extends AsyncTask<String, String, String> {

        /**
         * Before starting background thread Show Progress Bar Dialog
         * */
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            showDialog(progress_bar_type);
        }

        /**
         * Downloading file in background thread
         * */
        @Override
        protected String doInBackground(String... f_url) {
            int count;
            try {
                URL url = new URL(f_url[0]);
                URLConnection conection = url.openConnection();
                conection.connect();

                // this will be useful so that you can show a tipical 0-100%
                // progress bar
                int lenghtOfFile = conection.getContentLength();

                // download the file
                InputStream input = new BufferedInputStream(url.openStream(),
                        8192);

                // Output stream
                OutputStream output = new FileOutputStream(Environment
                        .getExternalStorageDirectory().toString()
                        + "/demo.mp4");

                byte data[] = new byte[1024];

                long total = 0;

                while ((count = input.read(data)) != -1) {
                    total += count;
                    // publishing the progress....
                    // After this onProgressUpdate will be called
                    publishProgress("" + (int) ((total * 100) / lenghtOfFile));

                    // writing data to file
                    output.write(data, 0, count);
                }

                // flushing output
                output.flush();

                // closing streams
                output.close();
                input.close();

            } catch (Exception e) {
                Log.e("Error: ", e.getMessage());
            }

            return null;
        }

        /**
         * Updating progress bar
         * */
        protected void onProgressUpdate(String... progress) {
            // setting progress percentage
            pDialog.setProgress(Integer.parseInt(progress[0]));
        }

        /**
         * After completing background task Dismiss the progress dialog
         * **/
        @Override
        protected void onPostExecute(String file_url) {
            // dismiss the dialog after the file was downloaded
            dismissDialog(progress_bar_type);

            // Displaying downloaded video into video view
            // Reading image path from sdcard
            String videopath = Environment.getExternalStorageDirectory()
                    .toString() + "/demo.mp4";
            // setting downloaded into image view

        }

    }