当APP在后台运行时，如何在顶部显示对话框

Question

我使用过警报对话框，但它仅在APP打开时显示对话框。

如果APP在后台运行，警报对话框将不会显示在顶部。

例如，时钟应用程序。

当时间到了时，它将在顶部显示对话框或提示窗口。

当APP在后台运行时，如何在顶部显示对话框???

Answer 1

您可以在应用处于后台时显示系统级警报。考虑以下代码来显示此类警报，例如

WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
        WindowManager.LayoutParams params = new WindowManager.LayoutParams(
                WindowManager.LayoutParams.MATCH_PARENT,
                WindowManager.LayoutParams.MATCH_PARENT,
                WindowManager.LayoutParams.TYPE_SYSTEM_ALERT
                        | WindowManager.LayoutParams.TYPE_SYSTEM_OVERLAY,
                WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL
                        | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
                PixelFormat.TRANSPARENT);
        params.height = WindowManager.LayoutParams.MATCH_PARENT;
        params.width = WindowManager.LayoutParams.MATCH_PARENT;
        params.format = PixelFormat.TRANSLUCENT;
        params.gravity = Gravity.TOP;
        LinearLayout ly = new LinearLayout(context);
        ly.setBackgroundColor(Color.BLACK);
        ly.setOrientation(LinearLayout.VERTICAL);
        ImageView iv = new ImageView(context);
        iv.setImageResource(R.drawable.ic_launcher);
        ly.addView(iv);
        TextView tv1 = new TextView(context);
        tv1.setWidth(params.width);
        tv1.setBackgroundColor(Color.BLUE);
        ly.addView(tv1);
        wm.addView(ly, params);

• 在清单中添加权限

  使用权限 android：name="android.permission.SYSTEM_ALERT_WINDOW"

Answer 2

我知道

这有点晚了，但由于没有公认的答案，你可以考虑一下。

您不必创建自定义视图并将其添加到窗口。如果您只想显示常规对话框，则可以执行以下操作。

创建一个服务类，并通过将其写入 AndroidManifest.xml 来让应用程序了解此服务。类似的东西;

<service android:name="your.package.name.PopupService"/>

然后实现服务;

public class PopupService extends Service {

private Intent myIntent;
MaterialDialog dialog;
@Override
public IBinder onBind(Intent intent) {
    return null;
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    this.myIntent = intent;
    showDialog(myIntent.getStringExtra("msg")); // you can send extra information to service via intent
    return super.onStartCommand(intent, flags, startId);
}
@Override
public void onCreate() {
    super.onCreate();
}
private void showDialog(String message)
{
    if (dialog != null) {
        if (dialog.isShowing()) {
            dialog.dismiss();
        }
    }
    dialog = new MaterialDialog.Builder(getApplicationContext())
            .content(message)
            .positiveText("OK")
            .negativeText("cancel")
            .positiveColor(getResources().getColor(R.color.colorAccent))
            .negativeColor(getResources().getColor(R.color.colorPrimary))
            .cancelable(true)
            .callback(new MaterialDialog.ButtonCallback() {
                @Override
                public void onPositive(MaterialDialog dialog) {
                    stopSelf();
                }
                @Override
                public void onNegative(MaterialDialog dialog) {
                    stopSelf();
                }
            })
            .dismissListener(new DialogInterface.OnDismissListener() {
                @Override
                public void onDismiss(DialogInterface dialog) {
                    stopSelf();
                }
            })
            .build();
    dialog.getWindow().setType(WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED
            | WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD
            | WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);
    dialog.show();
}
@Override
public void onDestroy() {
    if (dialog != null) {
        dialog.dismiss();
    }
    super.onDestroy();
}

}

当您要显示对话框时，只需调用服务，例如;

Intent intent = new Intent(MainActivity.this, PopupService.class);
intent.putExtra("msg","Test Message");
startService(intent);

还有一件事是，只需将此权限添加到AndroidManifest.xml

<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>

希望这对:)有所帮助