Question

我有一个方法public void writeEntry(Activity ctx, Entry entry)，它可以获取一些数据并且必须调用本机方法，这需要更长时间才能完成。
所以我创建了一个 AsyncTask 来处理 ProgressDialog 和本机方法。它在自己的 Activity 中运行良好来测试它，在 Activity 中我使用了一个回调接口等等。

在我的情况下，我有上述方法，必须执行 AsyncTask 。执行不能在该方法中，因为它不会停止进一步的执行在继续执行之前，我需要本机方法的结果有没有可能等待 AsyncTask 直到它完成？方法wait()不是一个选项，因为UI线程也会等待，因此 ProgressDialog 的意义将会丢失。

我可以使用给定参数中的方法runOnUiThread()，还是启动自己的活动的唯一解决方案？

Answer 1

所以我会尽可能多地解释

在AsyncTask中启动繁重的进程，但是在完成AsyncTask之后要执行的任何代码都将它放在一个单独的公共方法中。现在，一旦您完成了重度流程调用，即onPostExecute()中单独创建的方法。

所以psuuedo代码看起来像这样，

class main extends Activity {

    class Something extends AsyncTask<String, Integer, String> {

        protected void onPreExecute() {
            // Start your progress bar...
        }

        protected String doInBackground(String... params) {
            // Do your heavy stuff...
            return null;
        }

        protected void onPostExecute(String result) {
            // close your progress dialog and than call method which has
            // code you are wishing to execute after AsyncTask.
        }
    }

}

希望这会有所帮助，

祝你好运！

Answer 2

我的第一个解决方案是使用带有接口实现的回调方法，请参阅示例https://stackoverflow.com/a/6396376/390177。

在Android聊天中聊了一会儿之后，我听说有一个更加普遍的解决方案您可以将 IntentService 与 PendingIntent 结合使用。
通过 Intent 实现通信如果要使用 ProgressDialog ，则需要一个自己的 Activity ，例如注册 BroadcastReciever 和 IntentService < / em>每个广播发送实际状态。

但是现在就开始吧首先，我们创建 Activity ，其中包含 ProgressDialog 和已注册的 BroadcastReceiver 。 BroadcastReceiver 侦听有关更新和完成对话框的消息。

对于活动，我们需要布局......

<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#80000000"> </LinearLayout>

......以及相关代码：

public class ProgressActivity extends Activity { /** * ProgressDialog which is shown */ private ProgressDialog progessDialog_g; /** * Instance of the BroadcastReceiver */ private BroadcastReceiver receiver_g; /** * Identifier for the different settings of the ProgressDialog */ public static final String PROGRESS_DIALOG_BOOL_HORIZONTAL_BAR = "pbar_horizontal_bar"; public static final String PROGRESS_DIALOG_BOOL_CANCELABLE = "pbar_horizontal_cancelable"; public static final String PROGRESS_DIALOG_STR_MESSAGE = "pbar_message"; public static final String PROGRESS_DIALOG_INT_MAX = "pbar_max_bar"; public static final String PROGRESS_DIALOG_INT_VALUE = "pbar_value"; protected static final int PROGRESS_DIALOG_INT_MAX_VALUE = 100; @Override protected void onCreate(Bundle savedInstanceState){ super.onCreate(savedInstanceState); setContentView(R.layout.progress); progessDialog_g = new ProgressDialog(this); // Reads and sets the settings for the ProgressDialog Intent i = getIntent(); progessDialog_g.setCancelable(i.getBooleanExtra( PROGRESS_DIALOG_BOOL_CANCELABLE, false)); if (i.getBooleanExtra( PROGRESS_DIALOG_BOOL_HORIZONTAL_BAR, false)) { progessDialog_g.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); } else { progessDialog_g.setProgressStyle(ProgressDialog.STYLE_SPINNER); } progessDialog_g .setMessage(i .getStringExtra(PROGRESS_DIALOG_STR_MESSAGE)); progessDialog_g.setMax(i.getIntExtra( PROGRESS_DIALOG_INT_MAX, 100)); // Create the IntentFilter for the different broadcast messages IntentFilter iFilter = new IntentFilter( ExampleProgressService.PROGRESS_DIALOG_BROADCAST_INIT); iFilter.addAction(ExampleProgressService.PROGRESS_DIALOG_BROADCAST_UPDATE); iFilter.addAction(ExampleProgressService.PROGRESS_DIALOG_BROADCAST_FINISH); // Creates the BroadcastReceiver receiver_g = new BroadcastReceiver() { @Override public void onReceive(Context context, Intent intent){ Log.d(DefaultPreferences.DEBUG_PREFIX + "ProgressActivity", intent.getAction()); if (ExampleProgressService.PROGRESS_DIALOG_BROADCAST_INIT .equals(intent.getAction())) { // Sets the ProgressDialog style if (intent .getBooleanExtra( PROGRESS_DIALOG_BOOL_HORIZONTAL_BAR, false)) { progessDialog_g .setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); } else { progessDialog_g .setProgressStyle(ProgressDialog.STYLE_SPINNER); } // Shows the ProgressDialog progessDialog_g.show(); } else if (ExampleProgressService.PROGRESS_DIALOG_BROADCAST_UPDATE .equals(intent.getAction())) { // Updates the ProgressDialog int value = intent.getIntExtra( PROGRESS_DIALOG_INT_VALUE, -1); if (value != -1) { progessDialog_g.setProgress(value); } } else if (ExampleProgressService.PROGRESS_DIALOG_BROADCAST_FINISH .equals(intent.getAction())) { // Finishs the ProgressDialog progessDialog_g.cancel(); finish(); } } }; // Registers the BroadcastReceiver registerReceiver(receiver_g, iFilter); } @Override protected void onDestroy(){ unregisterReceiver(receiver_g); super.onDestroy(); } }

现在我们要使用 Activity ，所以我们先来调用它：

final Intent i = new Intent(parentActivity, <packages>.ProgressActivity); i.putExtra(ProgressActivity.PROGRESS_DIALOG_BOOL_CANCELABLE, cancelable_g); i.putExtra(ProgressActivity.PROGRESS_DIALOG_BOOL_HORIZONTAL_BAR, showProgress_g); i.putExtra(ProgressActivity.PROGRESS_DIALOG_STR_MESSAGE, message_g); i.putExtra(ProgressActivity.PROGRESS_DIALOG_INT_MAX, ProgressActivity.PROGRESS_DIALOG_INT_MAX_VALUE); parentActivity.startActivity(i);

所以我们一直在运行ProgressActivity，等待不同的广播。但首先我们需要发送广播的 IntentService 让我们走吧：

public class ExampleProgressService extends IntentService { /** * PendingIntent for callback. */ protected PendingIntent pi_g = null; private static final String DEBUG_TAG = "ExampleProgressService"; /** * Message identifier for ProgressDialog init */ public static final String PROGRESS_DIALOG_BROADCAST_INIT = "Dialog.Progress.Init"; /** * Message identifier for ProgressDialog finish */ public static final String PROGRESS_DIALOG_BROADCAST_FINISH = "Dialog.Progress.Finish"; /** * Message identifier for ProgressDialog update */ public static final String PROGRESS_DIALOG_BROADCAST_UPDATE = "Dialog.Progress.Update"; /** * Identifier of the result for intent content */ public static final String PROGRESS_DATA_RESULT = "Result"; /** * Identifier of the result error for intent content */ public static final String PROGRESS_DATA_RESULT_ERROR_MESSAGE = "Result.Error.Message"; /** * Identifier of the result error exception for intent content */ public static final String PROGRESS_DATA_RESULT_ERROR_EXCEPTION = "Result.Error.Exception"; /** * Identifier of the result status for intent content */ public static final String PROGRESS_DATA_RESULT_STATUS_BOOL = "Result.Status.boolean"; /** * Identifier of the pending intent for intent content */ public static final String PROGRESS_DATA_PENDING_RESULT = "PendingResult"; public ExampleProgressService() { super("ExampleProgressService"); } /** * Send the finish message. */ private void closeProgressActivity() { Intent intent = new Intent(PROGRESS_DIALOG_BROADCAST_FINISH); sendBroadcast(intent); } /** * Do some magic with the intent content */ private void extractVariablesFromIntentAndPrepare(Intent intent) throws Exception { pi_g = (PendingIntent) intent .getParcelableExtra(PROGRESS_DATA_PENDING_RESULT); if (pi_g == null) { throw new Exception("There is no pending intent!"); } /** * Sends an error message. */ private void failed(Exception e, String message) { Intent i = new Intent(); i.putExtra(PROGRESS_DATA_RESULT_ERROR_EXCEPTION, e); i.putExtra(PROGRESS_DATA_RESULT_ERROR_MESSAGE, message); send(i, false); } /** * Sends the init message. */ private void initProgressActivity() { Intent intent = new Intent(PROGRESS_DIALOG_BROADCAST_INIT); intent.putExtra(PROGRESS_DIALOG_BOOL_HORIZONTAL_BAR, multipart_g); sendBroadcast(intent); } /** * (non-Javadoc) * * @see android.app.IntentService#onHandleIntent(android.content.Intent) */ @Override protected void onHandleIntent(Intent intent) { extractVariablesFromIntentAndPrepare(intent); initProgressActivity(); // do your calculation here and implements following code Intent intent = new Intent(PROGRESS_DIALOG_BROADCAST_UPDATE); intent.putExtra(PROGRESS_DIALOG_INT_VALUE, progressValue); sendBroadcast(intent); // If you finished, use one of the two methods to send the result or an error success(result); failed(exception, optionalMessage); } /** * Sends the data to the calling Activity */ private void send(Intent resultData, boolean status) { resultData.putExtra(PROGRESS_DATA_RESULT_STATUS_BOOL, status); closeProgressActivity(); try { pi_g.send(this, Activity.RESULT_OK, resultData); } catch (PendingIntent.CanceledException e) { Log.e(DEBUG_TAG, "There is something wrong with the pending intent", e); } } /** * Sends the result message. */ private void success(String result) { Intent i = new Intent(); i.putExtra(PROGRESS_DATA_RESULT, result); send(i, true); } }

计算进度的结果应在 parentActivity 中提供，因此我们在 Activity 中创建 PendingIntent 并调用 IntentService 。

// Some identifier for the call int requestCode = 12345; final Intent sI = new Intent(ExampleProgressService.PROGRESS_SERVICE_ACTION); // Callback sI.putExtra(ExampleProgressService.PROGRESS_DATA_PENDING_RESULT, parentActivity .createPendingResult(requestCode, null, PendingIntent.FLAG_CANCEL_CURRENT)); // Service start parentActivity.startService(sI);

要接收结果，我们必须覆盖方法onActivityResult(int requestCode, int resultCode, Intent data)。

@Override protected void onActivityResult(int requestCode, int resultCode, Intent data){ // Compares the requestCode with the requestCode from above if (requestCode == ...) { if (data.getBooleanExtra(ExampleProgressService.PROGRESS_DATA_RESULT_STATUS_BOOL, false)) { // Calculation was success data.getStringExtra(ExampleProgressService.PROGRESS_DATA_RESULT); } else { // Calculation is failed data.getStringExtra(ExampleProgressService.PROGRESS_DATA_RESULT_ERROR_MESSAGE); ((Exception) data.getSerializableExtra(ExampleProgressService.PROGRESS_DATA_RESULT_ERROR_EXCEPTION)); } } }

这就是魔术，我希望它能帮到你。

等待使用ProgressDialog执行AsyncTask

2 个答案: