DownloadManager.ACTION_DOWNLOAD_COMPLETE

BroadcastReceiver receiver = new BroadcastReceiver() {

  @Override
  public void onReceive(Context context, Intent intent) {
    String action = intent.getAction();
    if (action.equals(DownloadManager.ACTION_DOWNLOAD_COMPLETE) ){
      // do something
    }
  }

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

public class MyDownloadCompleteReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
    }
}

<receiver android:enabled="true"
                android:name="MyDownloadCompleteReceiver"
                android:label="downloadCompleteReceiver">
        <intent-filter>
            <action android:name="android.intent.action.DOWNLOAD_COMPLETE" />
        </intent-filter>
    </receiver>