1. 主页面的设置，开启权限
//启动 计算器悬浮框 服务， 用于快速调出计算器。
public void startFloatingButtonService() {
if (FloatingButtonService.isStarted) {
return;
}
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (!Settings.canDrawOverlays(this)) {
// ToastUtils.showShort( “当前无权限，请授权”);
Toast.makeText(this, “当前无权限，请授权”, Toast.LENGTH_SHORT).show();
startActivityForResult(new Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION, Uri.parse(“package:” + getPackageName())), 0);
} else {
startService(new Intent(MainActivity.this, FloatingButtonService.class));
}
}
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == 0) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            if (!Settings.canDrawOverlays(this)) {
                Toast.makeText(this, "权限获取失败! 计算器悬浮窗口将不可用", Toast.LENGTH_SHORT).show();
            }else {
                // Toast.makeText(this, "授权成功", Toast.LENGTH_SHORT).show();
                startService(new Intent(MainActivity.this, FloatingButtonService.class));
            }
        }
    }
}

2. 在AndroidManifest定义权限
   在 application 里加
   加下面这句话service
   
   
   3. 创一个FloatingButtonService extends Service 这里开始设置悬浮窗大小什么的
   public class FloatingButtonService extends Service {
   public static boolean isStarted = false;
   int downTime ;//Button被按下时的时间
   int thisTime ;//while每次循环时的时间
   boolean onBtnTouch = false;//Button是否被按下
   private WindowManager windowManager;
   private WindowManager.LayoutParams layoutParams;
   private Context context;
   private ImageView imageView,imageView1;
   LinearLayout mFloatLayout,layout1;
   @Override
   public void onCreate() {
   super.onCreate();
   context = this;
   isStarted = true;
   windowManager = (WindowManager) getApplicationContext().getSystemService(getApplicationContext().WINDOW_SERVICE);
   layoutParams = new WindowManager.LayoutParams();
   if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
   layoutParams.type = WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY;
   } else {
   layoutParams.type = WindowManager.LayoutParams.TYPE_PHONE;
   }
   layoutParams.format = PixelFormat.RGBA_8888;
   layoutParams.gravity = Gravity.LEFT | Gravity.TOP;
   layoutParams.flags = WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE;
   layoutParams.width = 80;
   layoutParams.height = 160;
   layoutParams.x = 1200-layoutParams.width;
   layoutParams.y = 300;
   }

   @Nullable
   @Override
   public IBinder onBind(Intent intent) {
   return null;
   }

   @Override
   public int onStartCommand(Intent intent, int flags, int startId) {
   if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
   showFloatingWindow();
   }
   return super.onStartCommand(intent, flags, startId);
   }

   private void showFloatingWindow() {
   if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
   if (Settings.canDrawOverlays(this)) {
   layout1=new LinearLayout(getApplicationContext());
   //获取布局界面
   LayoutInflater inflater=LayoutInflater.from(getApplicationContext());
   mFloatLayout=(LinearLayout)inflater.inflate(R.layout.layout,null,false);
   layout1.addView(mFloatLayout);
   imageView = (ImageView) mFloatLayout.findViewById(R.id.close);
   imageView1 = (ImageView) mFloatLayout.findViewById(R.id.back);
   windowManager.addView(layout1,layoutParams);
   layout1.setOnTouchListener(new FloatingOnTouchListener());

           imageView.setOnTouchListener(new View.OnTouchListener() {
               @Override
               public boolean onTouch(View v, MotionEvent event) {
   
                   if (thisTime-downTime<2){
                      Intent intent = new Intent(FloatingButtonService.this, Main2Activity.class);
                      intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                      startActivity(intent);
               }
                return false;
              }
           });
       }
   
   }
   

   }
   //设置点击 移动 松开等事件
   private class FloatingOnTouchListener implements View.OnTouchListener {
   private int x;
   private int y;

   @Override
   public boolean onTouch(View view, MotionEvent event) {
       switch (event.getAction()) {
           case MotionEvent.ACTION_DOWN:
          // 悬浮球被按下时操作
               x = (int) event.getRawX();
               y = (int) event.getRawY();
               Calendar calendar = Calendar.getInstance();
               downTime = calendar.get(Calendar.SECOND);
               Toast.makeText(getApplicationContext(), downTime + ":" + "按下", Toast.LENGTH_SHORT).show();
               break;
           case MotionEvent.ACTION_MOVE:
           //移动时
               int nowX = (int) event.getRawX();
               int nowY = (int) event.getRawY();
               int movedX = nowX - x;
               int movedY = nowY - y;
               x = nowX;
               y = nowY;
               layoutParams.x = layoutParams.x + movedX;
               layoutParams.y = layoutParams.y + movedY;
               windowManager.updateViewLayout(view, layoutParams);
               break;
           default:
               break;
           case MotionEvent.ACTION_UP:
         //  结束时松开后
               Calendar calendar1 = Calendar.getInstance();
               thisTime = calendar1.get(Calendar.SECOND);
               Toast.makeText(getApplicationContext(), thisTime + ":" + "抬起", Toast.LENGTH_SHORT).show();
               break;
       }
       return false;
   }
   

   }
   }

4. layout布局