从小部件启动/停止服务答案

【问题标题】：Start/Stop Service from Widget从小部件启动/停止服务
【发布时间】：2013-07-05 02:51:48
【问题描述】：

我想从小部件内部启动一个服务，我知道我可以使用 PendingIntent 来做到这一点

PendingIntent intent = PendingIntent.getService(context, 0, new Intent(context, MyService.class), Intent.FLAG_ACTIVITY_NEW_TASK);
remoteViews.setOnClickPendingIntent(R.id.buttonWidgetStartService, intent);

但问题是我已经在该按钮上使用了 PendingIntent 用于其他目的。所以，我尝试使用

启动服务

context.startService(new Intent(context, MyService.class));

我在这里收到NullPointerException。

这是我的代码：

public class WiNetWidget extends AppWidgetProvider {

    public static String TOGGLE_WINET = "ToggleWiNetService";
    private static boolean serviceRunning = false;
    private static Intent serviceIntent;
    @Override
    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
        final int N = appWidgetIds.length;
        serviceIntent = new Intent(context, WiNetService.class);

        for (int i=0; i<N; i++) {
            int appWidgetId = appWidgetIds[i];
            RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.widget_winet);

            remoteViews.setViewVisibility(R.id.buttonWidgetLoading, View.INVISIBLE);
            remoteViews.setViewVisibility(R.id.buttonWidgetStartService, View.VISIBLE);

            Intent newIntent = new Intent(context, WiNetWidget.class);
            newIntent.setAction(TOGGLE_WINET);
            PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, newIntent, 0);
            remoteViews.setOnClickPendingIntent(R.id.buttonWidgetStartService, pendingIntent);
            remoteViews.setOnClickPendingIntent(R.id.buttonWidgetStopService, pendingIntent);

            appWidgetManager.updateAppWidget(appWidgetId, remoteViews);
            Log.i(TOGGLE_WINET, "updated");
        }
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        if(intent.getAction().equals(TOGGLE_WINET)) {
            RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.widget_winet);
            if(serviceRunning) {
                context.stopService(serviceIntent);
                remoteViews.setViewVisibility(R.id.buttonWidgetStartService, View.VISIBLE);
                remoteViews.setViewVisibility(R.id.buttonWidgetStopService, View.INVISIBLE);
                Toast.makeText(context, "serviceStopped", Toast.LENGTH_SHORT).show();
            } else {
                context.startService(serviceIntent);
                remoteViews.setViewVisibility(R.id.buttonWidgetStopService, View.VISIBLE);
                remoteViews.setViewVisibility(R.id.buttonWidgetStartService, View.INVISIBLE);
                Toast.makeText(context, "serviceStarted", Toast.LENGTH_SHORT).show();
            }
            serviceRunning=!serviceRunning;
            ComponentName componentName = new ComponentName(context, WiNetWidget.class);
            AppWidgetManager.getInstance(context).updateAppWidget(componentName, remoteViews);
        }
        super.onReceive(context, intent);
    }
}

注意：如果我删除包含startService 和stopService 的行，一切运行顺利。

提前致谢！！ :)

【问题讨论】：

如果你使用context.startService(new Intent(context, MyService.class));而不是变量serviceIntent，它是否有效？
@Neil Townsend：谢谢先生，它成功了。非常感谢！！你能解释一下为什么它以前不工作吗？再次感谢。 :)
完整答案见下文。

标签： android android-widget android-service

【解决方案1】：

问题是您创建了一次性Intent 一次，但多次使用它。每次要启动或停止Service 时，最好创建一个新的Intent，如下所示：

@Override
public void onReceive(Context context, Intent intent) {
    if(intent.getAction().equals(TOGGLE_WINET)) {
        RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.widget_winet);

        // Create a fresh intent 
        Intent serviceIntent = new Intent(context, WiNetService.class);

        if(serviceRunning) {
            context.stopService(serviceIntent);
            remoteViews.setViewVisibility(R.id.buttonWidgetStartService, View.VISIBLE);
            remoteViews.setViewVisibility(R.id.buttonWidgetStopService, View.INVISIBLE);
            Toast.makeText(context, "serviceStopped", Toast.LENGTH_SHORT).show();
        } else {
            context.startService(serviceIntent);
            remoteViews.setViewVisibility(R.id.buttonWidgetStopService, View.VISIBLE);
            remoteViews.setViewVisibility(R.id.buttonWidgetStartService, View.INVISIBLE);
            Toast.makeText(context, "serviceStarted", Toast.LENGTH_SHORT).show();
        }
        serviceRunning=!serviceRunning;
        ComponentName componentName = new ComponentName(context, WiNetWidget.class);
        AppWidgetManager.getInstance(context).updateAppWidget(componentName, remoteViews);
    }
    super.onReceive(context, intent);
}

【讨论】：