Android Studio中窗口类型2002的权限被拒绝

Question

今天我安装了最新版本的Android Studio

我正在学习Android中的Floating Widgets

我开始应用这个例子

https://www.spaceotechnologies.com/android-floating-widget-tutorial/

它汇编好了

但是当我在模拟器中运行它时会崩溃

给我这个错误

08-28 22:52:02.932 7400-7400/com.asmgx.MyApp.MyApp E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.asmgx.MyApp.MyApp, PID: 7400
    java.lang.RuntimeException: Unable to create service com.asmgx.MyApp.MyApp.FloatWidgetService: android.view.WindowManager$BadTokenException: Unable to add window android.view.ViewRootImpl$W@7c93828 -- permission denied for window type 2002
        at android.app.ActivityThread.handleCreateService(ActivityThread.java:3544)
        at android.app.ActivityThread.access$1300(ActivityThread.java:199)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1666)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
     Caused by: android.view.WindowManager$BadTokenException: Unable to add window android.view.ViewRootImpl$W@7c93828 -- permission denied for window type 2002
        at android.view.ViewRootImpl.setView(ViewRootImpl.java:822)
        at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:356)
        at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:93)
        at com.asmgx.MyApp.MyApp.FloatWidgetService.onCreate(FloatWidgetService.java:36)
        at android.app.ActivityThread.handleCreateService(ActivityThread.java:3532)
        at android.app.ActivityThread.access$1300(ActivityThread.java:199) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1666) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:193) 
        at android.app.ActivityThread.main(ActivityThread.java:6669) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858) 

我尝试解决问题并找到了这个链接

无法添加窗口android.view.ViewRoot$W@44da9bc0 - 此窗口类型的权限被拒绝

他们建议将此行添加到已添加的清单中

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

有谁知道为什么我得到这个？

PS.我使用Android 28的模拟器和Android 27的另一个

Answer 1

发生这种情况是因为示例中的targetSdkVersion与targetSdkVersion不同.尝试将其减少到22或使用标志TYPE_APPLICATION_OVERLAY而不是WindowManager.LayoutParams中的TYPE_PHONE:

WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY 

Answer 2

这对我有用。我敢肯定它可以简化，但在其他方面可以很好地工作。
只需替换TYPE_PHONE为TYPE_APPLICATION_OVERLAY（且仅当）用户等于或高于Oreo的用户：

final WindowManager.LayoutParams params;
    if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
        params = new WindowManager.LayoutParams(
                WindowManager.LayoutParams.WRAP_CONTENT,
                WindowManager.LayoutParams.WRAP_CONTENT,
                WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY,
                WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
                PixelFormat.TRANSLUCENT);
    } else {
        params = new WindowManager.LayoutParams(
                WindowManager.LayoutParams.WRAP_CONTENT,
                WindowManager.LayoutParams.WRAP_CONTENT,
                WindowManager.LayoutParams.TYPE_PHONE,
                WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
                PixelFormat.TRANSLUCENT);
    }