ASyncTask-我想通过按钮从互联网下载文件

Question

I'm still new to the whole coding thing, but I would like some help with ASyncTask and how to allow it to download my app from the internet straight to my phone through notification or just in the SD Card.

I already have a button inside the activity_main.xml layout which is:

<Button
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:id="@+id/UpdateButton"
    android:text="@string/Update"
    android:background="#6c0005"
    android:textColor="#ffffff"
    android:textSize="12dp" />

In my MainActivity.Java class I just have right now a button connecting to a string and intent to redirect it to a webview to download it:

case R.id.UpdateButton:
    Intent browserIntent = new Intent(Intent.ACTION_VIEW,
    Uri.parse(getString(R.string.UpdateAV)));
    startActivity(browserIntent);
    break;

but instead of that, I would like the file to download straight to the phone or a progress bar saying it is downloading to the External memory or SD Card.

Any help would be appreciated.

Answer 1

this is just an example that how you can download a file, you would have to write an equivalent code for this in Android if you want to use AsyncTask , in which you will do the same work in the doInBacground() method.

public class DownloadTest {

public static void main(String[] args) {

    Thread thread = new Thread(){
        @Override
        public void run() {
            // TODO Auto-generated method stub
            super.run();
            try {
                dowanloadFile(new URL("some url"), new File("some file"));
            } catch (MalformedURLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    };
    thread.start();


   }

private static void dowanloadFile(URL url, File file){
    try {
        FileUtils.copyURLToFile(url, file );
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}
}

this code code uses commons-io-2.4.jar library,

you can get little more code her Example

you can get path to download at SD card like this

final String path = Environment.getExternalStorageDirectory().getAbsolutePath();

with AsycnTask it would be like this

private class MtDownloadTask extends AsyncTask<Void, Void ,Void>{

    URL someUrl = new URL("your url String"); //
    File someFile = new File("your file, where you want to save the data");

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
    }

    @Override
    protected Void doInBackground(Void... params) {
        return null;
        FileUtils.copyURLToFile(url, file);
    }

    @Override
    protected void onPostExecute(Void aVoid) {
        super.onPostExecute(aVoid);
    }

}

make sure you do have internet permission to your app, to do that add this line to your AndroidManifest.xml

    <uses-permission android:name="android.permission.INTERNET"/>