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看似简单的要求 - 从IntentService更新UI。在下面的拍摄中，当点击Start Service按钮时，我需要在TextView以上显示ProgressBar，并在延迟之后删除ProgressBar。无法从IntentService更新UI
找到很多答案对SO，但不知何故无法依然破解它。我从this了解到LocalBroadcastManager是一个很好的选择。我也尝试过this（与Handler s的方法），但它也未能显示ProgressBar。最后，根据this回答，这里是我结束了。到目前为止，我所管理的输出仅仅是Toast s，在完成所有记录之后连续出现。
非常感谢，如果你能指出我出错的地方，现在已经挣扎了相当一段时间了。提前谢谢了！
MainActivity更新
public class MainActivity extends AppCompatActivity
{
private static final String TAG = "MainActivity";
private ProgressBar pb;
private MyBroadcastReceiver myBroadcastReceiver;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
pb = (ProgressBar) findViewById(R.id.pb);
myBroadcastReceiver = new MyBroadcastReceiver();
LocalBroadcastManager.getInstance(this).registerReceiver(myBroadcastReceiver, new IntentFilter("ACTION"));
}
private void updateUI(boolean show)
{
if (show)
pb.setVisibility(View.VISIBLE);
else
pb.setVisibility(View.GONE);
// Toast.makeText(this, "UI Updated...", Toast.LENGTH_LONG).show();
}
public void startIt(View view)
{
Intent intent = new Intent(this, NanisIntentService.class);
startService(intent);
}
public class MyBroadcastReceiver extends BroadcastReceiver
{
@Override
public void onReceive(final Context context, Intent intent)
{
String action = intent.getAction();
Log.e(TAG, "In onReceive(): " + action);
if (action.equals("ACTION"))
{
updateUI(true);
} // of if (action = "ACTION")
else if (action.equals("NOITCA"))
{
updateUI(false);
} // of else of if (action = "ACTION")
} // of onReceive()
} // of class MyBroadcastReceiver
}
IntentService更新
public class NanisIntentService extends IntentService
{
private static final String TAG = "NanisIntentService";
public NanisIntentService()
{
super("NanisIntentService");
}
@Override
protected void onHandleIntent(Intent intent)
{
Log.e(TAG, "In onHandleIntent(): Intent is being serviced");
LocalBroadcastManager.getInstance(testing.com.myintentservice.NanisIntentService.this).sendBroadcast(new Intent().setAction("ACTION"));
int i = 0;
while (i <= 50)
{
try
{
Thread.sleep(50);
i++;
Log.e("", "" + i);
} catch (InterruptedException e)
{
e.printStackTrace();
}
}
}
@Override
public void onDestroy()
{
super.onDestroy();
LocalBroadcastManager.getInstance(testing.com.myintentservice.NanisIntentService.this).sendBroadcast(new Intent().setAction("NOITCA"));
Log.e(TAG, "In onDestroy(): The service has been destroyed");
}
}
@Override
public void onStart(Intent intent, int startId)
{
super.onStart(intent, startId);
LocalBroadcastManager.getInstance(testing.com.myintentservice.NanisIntentService.this).sendBroadcast(new Intent().setAction("ACTION"));
}
@Override
public void onDestroy()
{
super.onDestroy();
LocalBroadcastManager.getInstance(testing.com.myintentservice.NanisIntentService.this).sendBroadcast(new Intent().setAction("NOITCA"));
Log.e(TAG, "In onDestroy(): The service has been destroyed");
}
}
@Override
public void onDestroy()
{
super.onDestroy();
LocalBroadcastManager.getInstance(testing.com.myintentservice.NanisIntentService.this).sendBroadcast(new Intent().setAction("NOITCA"));
Log.e(TAG, "In onDestroy(): The service has been destroyed");
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="testing.com.myintentservice.MainActivity">
<ProgressBar
android:id="@+id/pb"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@+id/tv"
android:layout_centerHorizontal="true"
android:indeterminate="true"
android:visibility="gone"/>
<TextView
android:id="@+id/tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:text="Hello IntentService!"
android:textColor="#1298CE"
android:textSize="32sp"/>
<Button
android:id="@+id/bt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:text="Start Service"
android:onClick="startIt"/>
</RelativeLayout>
AndroidManifest
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
<service android:name="testing.com.myintentservice.NanisIntentService"/>
</application>
感谢您的快速反应，@CommonsWare！对不起，但我错过了提及这是一个_experiment_，_PoC_--因此，而不是延迟2.5秒，将有一个不确定的互联网下载，在此期间，我需要显示'ProgressBar'。你的建议是否仍然有效？非常感谢您是否可以在可能的情况下详细阐述解决方案。干杯! –
@NarayanaJ：“你的建议是否仍然有效？” - 假设“ProgressBar”的持续时间取决于服务，那么你可以按照这种方式开始。为“show”和“hide”使用两个不同的'LocalBroadcastManager'事件。在短期内，延迟服务，以服务所做的“假工作”的形式出现。然后，您可以用真正的工作来替换假工作，并且您的'ProgressBar'逻辑不必更改。 – CommonsWare
请在我的原始问题中检查更新的代码。我做的是： - 将'假工作'移动到'IntentService' - 设置2广播行动，一个显示和一个隐藏'ProgressBar'我也不确定Runnable调用你最初提出的建议）仍然应该提出，也不应该如此。 “ProgressBar”仍然不显示。请回复。 –