我必须使用intentservice创建一个从服务器下载文件的应用程序，我已经创建了下载服务并将其传递给接收者，但我不知道从哪里开始。结果应该是一个数组字符串，它将通过适配器填充listview。但我不知道如何将结果从接收器传递到适配器所在的主活动。

public class MainActivity extends AppCompatActivity {
    ArrayList<PlaylistItem> arrayOfUsers = new ArrayList<PlaylistItem>();
    // Create the adapter to convert the array to views
    PlaylistAdapter adapter = new PlaylistAdapter(this, arrayOfUsers);
    // Attach the adapter to a ListView
    ListView listView = (ListView) findViewById(R.id.listView);
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Intent downloadIntent = new Intent(this, DownloadService.class);
        downloadIntent.putExtra("url", "url to be called" );
        downloadIntent.putExtra("type","playlist");
        downloadIntent.putExtra("receiver", new DownloadReceiver(new Handler()));
        startService(downloadIntent);
        listView.setAdapter(adapter);
    }
}

下载服务

public class DownloadService extends IntentService {
    public static final int UPDATE_PROGRESS = 1000;
    public static final int PLAYLIST_READY = 2000;
    private ResultReceiver receiver;
    public DownloadService() {
        super("DownloadService");
    }
    @Override
    protected void onHandleIntent(Intent intent) {
        String urlToDownload = intent.getStringExtra("url");
        receiver = (ResultReceiver) intent.getParcelableExtra("receiver");
        String type= intent.getStringExtra("type");
// se apeleaza ori downloadPlaylist ori downloadMusic
// in functie de ce url am primit in intent
        if(type=="playlist")
        {
          downloadPlaylist(urlToDownload);
        }
}
private void downloadPlaylist(String urlToDownload){
        String str=null;
        try {
            URL url = new URL(urlToDownload);
            URLConnection connection = url.openConnection();
            connection.connect();
            // this will be useful so that you can show a typical 0-100% progress bar
            int fileLength = connection.getContentLength();
            File musicDirectory = new
                    File(Environment.getExternalStorageDirectory(),"music");
            if (!musicDirectory.exists())
                musicDirectory.mkdirs();
            // download the file
            InputStream input = new BufferedInputStream(connection.getInputStream());
            OutputStream output = new FileOutputStream(musicDirectory+urlToDownload);
            str=input.toString();
            byte data[] = new byte[1024];
            long total = 0;
            int count;
            while ((count = input.read(data)) != -1) {
                total += count;
                // publishing the progress....
                Bundle resultData = new Bundle();
                resultData.putInt("progress" ,(int) (total * 100 / fileLength));
                output.write(data, 0, count);
            }
            output.flush();
            output.close();
            input.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        Bundle resultData = new Bundle();
        resultData.putInt("progress" ,100);
        receiver.send(UPDATE_PROGRESS, resultData);
    }

public class DownloadReceiver extends ResultReceiver {
        public DownloadReceiver(Handler handler) {
            super(handler);
        }
        @Override
        protected void onReceiveResult(int resultCode, Bundle resultData) {
            super.onReceiveResult(resultCode, resultData);
            if (resultCode == UPDATE_PROGRESS) {
                //send data to Main ACtivity
                // update progress bar
            }
          }
    }

我不知道如何从mainactivity中的接收器调用数组，或者反过来调用数组来填充它。如果你能给我举个例子。谢谢您！