Question

我希望我的应用程序在单击按钮时启动服务，并且服务应在后台运行以在一天中的特定时间显示通知。我有以下代码来执行此操作。但它显示了我不理解的错误。我是Android新手，这是我第一个使用Service的应用。任何帮助，将不胜感激。提前谢谢。

的AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.newtrial"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="18" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.newtrial.CreateNotificationActiviy"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name="com.example.newtrial.ResultActivity"
            android:label="@string/title_activity_result" >

        </activity>

        <service android:enabled="true" android:name=".UpdaterServiceManager" />

    </application>

</manifest>

CreateNotificationActiviy.java

package com.example.newtrial;

import android.os.Bundle;
import android.app.Activity;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class CreateNotificationActiviy extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.create_notification_activiy);

        Button b=(Button)findViewById(R.id.button1);
        b.setOnClickListener(new OnClickListener(){

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub      
                startService(new Intent(CreateNotificationActiviy.this, UpdaterServiceManager.class));
            }

        });

    }

    public void createNotification(View view) {
        // Prepare intent which is triggered if the
        // notification is selected
        Intent intent = new Intent(this, ResultActivity.class);
        PendingIntent pIntent = PendingIntent.getActivity(this, 0, intent, 0);

        // Build notification
        // Actions are just fake
        Notification noti = new Notification.Builder(this)
            .setContentTitle("Notification Title")
            .setContentText("Click here to read").setSmallIcon(R.drawable.ic_launcher)
            .setContentIntent(pIntent)
            .build();
        NotificationManager notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
        // hide the notification after its selected
        noti.flags |= Notification.FLAG_AUTO_CANCEL;

        notificationManager.notify(0, noti);

      } 

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.create_notification_activiy, menu);
        return true;
    }

}

UpdaterServiceManager.java

package com.example.newtrial;

import java.util.Calendar;
import java.util.Timer;
import java.util.TimerTask;

import android.app.AlertDialog;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.os.IBinder;
import android.util.Log;
import android.view.View;

public class UpdaterServiceManager extends Service {

    private final int UPDATE_INTERVAL = 60 * 1000;
    private Timer timer = new Timer();
    private static final int NOTIFICATION_EX = 1;
    private NotificationManager notificationManager;
    CreateNotificationActiviy not;

    public UpdaterServiceManager() {
        not=new CreateNotificationActiviy();
    }

    @Override
    public IBinder onBind(Intent intent) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public void onCreate() {
        // code to execute when the service is first created
        super.onCreate();
        Log.i("MyService", "Service Started.");
        showNotification();
    }

    public void showNotification()
    {
        final Calendar cld = Calendar.getInstance();

        int time = cld.get(Calendar.HOUR_OF_DAY);
        if(time>12)
        {
                  not.createNotification(null); 

        }
        else
        {
            AlertDialog.Builder alert=new AlertDialog.Builder(this);
            alert.setMessage("Not yet");
            alert.setTitle("Error");
            alert.setPositiveButton("OK", null);
            alert.create().show();
        }
    }

    @Override
    public void onDestroy() {
        if (timer != null) {
            timer.cancel();
        }
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startid) 
    {
        return START_STICKY;
    }

    private void stopService() {
        if (timer != null) timer.cancel();
    }

}

ResultActivity.java

package com.example.newtrial;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.widget.TextView;

public class ResultActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_result);
        TextView tv=(TextView)findViewById(R.id.textView1);
        tv.setText("After notification is clicked" );
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.result, menu);
        return true;
    }

}

logcat的

12-10 12:14:04.286: I/Process(872): Sending signal. PID: 872 SIG: 9
12-10 12:14:11.774: I/MyService(893): Service Started.
12-10 12:14:12.094: D/AndroidRuntime(893): Shutting down VM
12-10 12:14:12.094: W/dalvikvm(893): threadid=1: thread exiting with uncaught exception (group=0x414c4700)
12-10 12:14:12.124: E/AndroidRuntime(893): FATAL EXCEPTION: main
12-10 12:14:12.124: E/AndroidRuntime(893): java.lang.RuntimeException: Unable to create service com.example.newtrial.UpdaterServiceManager: android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application
12-10 12:14:12.124: E/AndroidRuntime(893):  at android.app.ActivityThread.handleCreateService(ActivityThread.java:2587)
12-10 12:14:12.124: E/AndroidRuntime(893):  at android.app.ActivityThread.access$1600(ActivityThread.java:141)
12-10 12:14:12.124: E/AndroidRuntime(893):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1338)
12-10 12:14:12.124: E/AndroidRuntime(893):  at android.os.Handler.dispatchMessage(Handler.java:99)
12-10 12:14:12.124: E/AndroidRuntime(893):  at android.os.Looper.loop(Looper.java:137)
12-10 12:14:12.124: E/AndroidRuntime(893):  at android.app.ActivityThread.main(ActivityThread.java:5103)
12-10 12:14:12.124: E/AndroidRuntime(893):  at java.lang.reflect.Method.invokeNative(Native Method)
12-10 12:14:12.124: E/AndroidRuntime(893):  at java.lang.reflect.Method.invoke(Method.java:525)
12-10 12:14:12.124: E/AndroidRuntime(893):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
12-10 12:14:12.124: E/AndroidRuntime(893):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
12-10 12:14:12.124: E/AndroidRuntime(893):  at dalvik.system.NativeStart.main(Native Method)
12-10 12:14:12.124: E/AndroidRuntime(893): Caused by: android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application
12-10 12:14:12.124: E/AndroidRuntime(893):  at android.view.ViewRootImpl.setView(ViewRootImpl.java:563)
12-10 12:14:12.124: E/AndroidRuntime(893):  at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:269)
12-10 12:14:12.124: E/AndroidRuntime(893):  at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69)
12-10 12:14:12.124: E/AndroidRuntime(893):  at android.app.Dialog.show(Dialog.java:281)
12-10 12:14:12.124: E/AndroidRuntime(893):  at com.example.newtrial.UpdaterServiceManager.showNotification(UpdaterServiceManager.java:65)
12-10 12:14:12.124: E/AndroidRuntime(893):  at com.example.newtrial.UpdaterServiceManager.onCreate(UpdaterServiceManager.java:41)
12-10 12:14:12.124: E/AndroidRuntime(893):  at android.app.ActivityThread.handleCreateService(ActivityThread.java:2577)
12-10 12:14:12.124: E/AndroidRuntime(893):  ... 10 more

Answer 1

问题相对较旧，但我希望这篇文章可能与其他人有关。

TL; DR：使用AlarmManager来安排任务，使用IntentService，查看示例代码here;

这个测试应用程序（和指令）的内容是：

简单的helloworld应用程序，每2小时向您发送一次通知。点击通知 - 在应用中打开辅助活动;删除通知曲目。

您何时应该使用它：

一旦您需要按计划运行某项任务。我自己的情况：每天一次，我想从服务器上获取新内容，根据我收到的内容撰写通知并将其显示给用户。

该怎么做：

首先，让我们创建两个活动：MainActivity，它启动通知服务和NotificationActivity，它将通过点击通知启动：

activity_main.xml中

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp">
    <Button
        android:id="@+id/sendNotifications"
        android:onClick="onSendNotificationsButtonClick"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Start Sending Notifications Every 2 Hours!" />
</RelativeLayout>

MainActivity.java

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void onSendNotificationsButtonClick(View view) {
        NotificationEventReceiver.setupAlarm(getApplicationContext());
    }   
}

和NotificationActivity是您可以提出的任何随机活动。 NB！不要忘记将这两项活动添加到AndroidManifest中。

然后让我们创建WakefulBroadcastReceiver广播接收器，我在上面的代码中调用 NotificationEventReceiver 。

在此，我们将设置AlarmManager每2小时（或使用任何其他频率）触发PendingIntent，并在onReceive()方法中指定此意图的已处理操作。在我们的例子中 - 清醒启动IntentService，我们将在后面的步骤中指定。此IntentService会为我们生成通知。

此外，此接收器将包含一些辅助方法，如创建PendintIntents，稍后我们将使用

NB1！当我使用WakefulBroadcastReceiver时，我需要在清单中添加额外权限：<uses-permission android:name="android.permission.WAKE_LOCK" />

NB2！我使用它的唤醒版本的广播接收器，因为我想确保设备在IntentService的操作期间不会重新进入睡眠状态。在hello-world中，它并不重要（我们的服务中没有长时间运行的操作，但想象一下，如果在此操作期间必须从服务器获取一些相对较大的文件）。详细了解Device Awake here。

NotificationEventReceiver.java

public class NotificationEventReceiver extends WakefulBroadcastReceiver {

    private static final String ACTION_START_NOTIFICATION_SERVICE = "ACTION_START_NOTIFICATION_SERVICE";
    private static final String ACTION_DELETE_NOTIFICATION = "ACTION_DELETE_NOTIFICATION";
    private static final int NOTIFICATIONS_INTERVAL_IN_HOURS = 2;

    public static void setupAlarm(Context context) {
        AlarmManager alarmManager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
        PendingIntent alarmIntent = getStartPendingIntent(context);
        alarmManager.setRepeating(AlarmManager.RTC_WAKEUP,
                getTriggerAt(new Date()),
                NOTIFICATIONS_INTERVAL_IN_HOURS * AlarmManager.INTERVAL_HOUR,
                alarmIntent);
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        Intent serviceIntent = null;
        if (ACTION_START_NOTIFICATION_SERVICE.equals(action)) {
            Log.i(getClass().getSimpleName(), "onReceive from alarm, starting notification service");
            serviceIntent = NotificationIntentService.createIntentStartNotificationService(context);
        } else if (ACTION_DELETE_NOTIFICATION.equals(action)) {
            Log.i(getClass().getSimpleName(), "onReceive delete notification action, starting notification service to handle delete");
            serviceIntent = NotificationIntentService.createIntentDeleteNotification(context);
        }

        if (serviceIntent != null) {
            startWakefulService(context, serviceIntent);
        }
    }

    private static long getTriggerAt(Date now) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(now);
        //calendar.add(Calendar.HOUR, NOTIFICATIONS_INTERVAL_IN_HOURS);
        return calendar.getTimeInMillis();
    }

    private static PendingIntent getStartPendingIntent(Context context) {
        Intent intent = new Intent(context, NotificationEventReceiver.class);
        intent.setAction(ACTION_START_NOTIFICATION_SERVICE);
        return PendingIntent.getBroadcast(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
    }

    public static PendingIntent getDeleteIntent(Context context) {
        Intent intent = new Intent(context, NotificationEventReceiver.class);
        intent.setAction(ACTION_DELETE_NOTIFICATION);
        return PendingIntent.getBroadcast(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
    }
}

现在让我们创建一个IntentService来实际创建通知。

在那里，我们指定onHandleIntent()，这是对{em> NotificationEventReceiver 我们在startWakefulService方法中传递的意图的回应。

如果是删除操作 - 我们可以将其记录到我们的分析中，例如。如果它是开始通知意图 - 然后使用NotificationCompat.Builder我们正在撰写新通知并按NotificationManager.notify显示。在撰写通知时，我们还设置了单击和删除操作的待处理意图。相当容易。

NotificationIntentService.java

public class NotificationIntentService extends IntentService {

    private static final int NOTIFICATION_ID = 1;
    private static final String ACTION_START = "ACTION_START";
    private static final String ACTION_DELETE = "ACTION_DELETE";

    public NotificationIntentService() {
        super(NotificationIntentService.class.getSimpleName());
    }

    public static Intent createIntentStartNotificationService(Context context) {
        Intent intent = new Intent(context, NotificationIntentService.class);
        intent.setAction(ACTION_START);
        return intent;
    }

    public static Intent createIntentDeleteNotification(Context context) {
        Intent intent = new Intent(context, NotificationIntentService.class);
        intent.setAction(ACTION_DELETE);
        return intent;
    }

    @Override
    protected void onHandleIntent(Intent intent) {
        Log.d(getClass().getSimpleName(), "onHandleIntent, started handling a notification event");
        try {
            String action = intent.getAction();
            if (ACTION_START.equals(action)) {
                processStartNotification();
            }
            if (ACTION_DELETE.equals(action)) {
                processDeleteNotification(intent);
            }
        } finally {
            WakefulBroadcastReceiver.completeWakefulIntent(intent);
        }
    }

    private void processDeleteNotification(Intent intent) {
        // Log something?
    }

    private void processStartNotification() {
        // Do something. For example, fetch fresh data from backend to create a rich notification?

        final NotificationCompat.Builder builder = new NotificationCompat.Builder(this);
        builder.setContentTitle("Scheduled Notification")
                .setAutoCancel(true)
                .setColor(getResources().getColor(R.color.colorAccent))
                .setContentText("This notification has been triggered by Notification Service")
                .setSmallIcon(R.drawable.notification_icon);

        PendingIntent pendingIntent = PendingIntent.getActivity(this,
                NOTIFICATION_ID,
                new Intent(this, NotificationActivity.class),
                PendingIntent.FLAG_UPDATE_CURRENT);
        builder.setContentIntent(pendingIntent);
        builder.setDeleteIntent(NotificationEventReceiver.getDeleteIntent(this));

        final NotificationManager manager = (NotificationManager) this.getSystemService(Context.NOTIFICATION_SERVICE);
        manager.notify(NOTIFICATION_ID, builder.build());
    }
}

差不多完成了。现在我还为BOOT_COMPLETED，TIMEZONE_CHANGED和TIME_SET事件添加了广播接收器，以重新设置我的AlarmManager，一旦设备重启或时区已经改变（例如，用户从美国飞到欧洲，你不想弹出通知在半夜，但当地时间很粘:-)）。

NotificationServiceStarterReceiver.java
```
public final class NotificationServiceStarterReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        NotificationEventReceiver.setupAlarm(context);
    }
}
```

我们还需要在AndroidManifest中注册我们所有的服务，广播接收器：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="klogi.com.notificationbyschedule">

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

    <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=".notifications.NotificationIntentService"
            android:enabled="true"
            android:exported="false" />

        <receiver android:name=".broadcast_receivers.NotificationEventReceiver" />
        <receiver android:name=".broadcast_receivers.NotificationServiceStarterReceiver">
            <intent-filter>
                <action android:name="android.intent.action.BOOT_COMPLETED" />
                <action android:name="android.intent.action.TIMEZONE_CHANGED" />
                <action android:name="android.intent.action.TIME_SET" />
            </intent-filter>
        </receiver>

        <activity
            android:name=".NotificationActivity"
            android:label="@string/title_activity_notification"
            android:theme="@style/AppTheme.NoActionBar"/>
    </application>

</manifest>

就是这样！

您可以找到此项目的源代码here。我希望，你会发现这篇文章很有用。

Answer 2

您的错误发生在onCreate和showNotification方法的UpdaterServiceManager中。

您正试图从notification展示Service using Activity Context。而Every Service has its own Context,只是使用它。您不需要pass a Service an Activity's Context.我不明白为什么您需要特定的Activity's Context to show Notification.

将 createNotification方法放在UpdateServiceManager.class 中。 删除CreateNotificationActivity 不是来自服务。

您无法通过非活动的上下文显示应用程序窗口/对话框。尝试传递有效的活动参考

使用服务运行后台并创建通知

2 个答案:

这个测试应用程序（和指令）的内容是：

您何时应该使用它：

该怎么做：

就是这样！