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我正在尝试在下载文件时创建下载进度条。我按照本教程进行操作，但是我只能在下载图像或 mp3 等文件时计算进度条。

我需要能够下载的是诸如这些的api响应，但我无法获取它们的文件大小以便为我的进度条提供参考。

        URL url = new URL(f_url[0]);
        URLConnection connection = url.openConnection();
        connection.connect();
        // this will be useful so that you can show a typical 0-100% progress bar
        int lenghtOfFile = connection.getContentLength();

当用于 API 响应时，文件大小为 -1，因此整个函数是错误的。

在下载这些文件时，有什么方法可以识别它们的大小或创建进度条的任何替代方法。

编辑：我已经在使用异步任务并且它正在工作，唯一的问题是我无法增加我的进度条，因为我无法获得文件大小。

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1 回答 1

3

你也可以使用这个：

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();
        // getting file length
        int lenghtOfFile = conection.getContentLength();

        // input stream to read file - with 8k buffer
        InputStream input = new BufferedInputStream(url.openStream(), 8192);

        // Output stream to write file
        OutputStream output = new FileOutputStream("/sdcard/downloadedfile.jpg");

        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 image into image view
    // Reading image path from sdcard
    String imagePath = Environment.getExternalStorageDirectory().toString() + "/downloadedfile.jpg";
    // setting downloaded into image view
    my_image.setImageDrawable(Drawable.createFromPath(imagePath));
}

 }
于 2013-08-22T12:34:39.237 回答