Android悬浮窗的实现步骤

@SystemService(Context.WINDOW_SERVICE)
public interface WindowManager extends ViewManager {
	...
}

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

val windowManager = getSystemService(WINDOW_SERVICE) as WindowManager

// view – The view to be added to this window.
	// params – The LayoutParams to assign to view.
   public void addView(View view, ViewGroup.LayoutParams params);

        val layoutParams = 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
        }

//检测是否允许开启悬浮窗
Settings.canDrawOverlays(context)

startActivity(Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION))

class FloatingService : Service() {
    override fun onCreate() {
        super.onCreate()
    }
    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
        showFloatingWindow();
        return super.onStartCommand(intent, flags, startId)
    }
    override fun onBind(intent: Intent?): IBinder? {
        return null
    }
    /**
     * 显示悬浮窗
     */
    private fun showFloatingWindow() {
        // 获取WindowManager服务
        val windowManager = getSystemService(WINDOW_SERVICE) as WindowManager
        // 新建悬浮窗控件
        val button = Button(applicationContext)
        button.text = "Floating Window"
        button.setBackgroundColor(Color.BLUE)
        // 设置LayoutParam
        val layoutParams = 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.flags =
            WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL or WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
        layoutParams.width = ActionBar.LayoutParams.WRAP_CONTENT
        layoutParams.height = ActionBar.LayoutParams.WRAP_CONTENT
        layoutParams.x = 300
        layoutParams.y = 300
        // 将悬浮窗控件添加到WindowManager
        windowManager.addView(button, layoutParams);
    }
}

       viewBinding.btnFloating.setOnClickListener {
            if (Settings.canDrawOverlays(this)) {//检测是否具有悬浮窗权限
                startService(Intent(this,FloatingService::class.java))
            } else {
                startActivity(Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION));
            }
        }

        var x = 0
        var y = 0
        button.setOnTouchListener { view, event ->
            when (event.action) {
                MotionEvent.ACTION_DOWN -> {
                    x = event.rawX.toInt()
                    y = event.rawY.toInt()
                }
                MotionEvent.ACTION_MOVE -> {
                    val nowX = event.rawX.toInt()
                    val nowY = event.rawY.toInt()
                    val movedX = nowX - x
                    val movedY = nowY - y
                    x = nowX
                    y = nowY
                    layoutParams.x = layoutParams.x + movedX
                    layoutParams.y = layoutParams.y + movedY
                    // 更新悬浮窗控件布局
                    windowManager.updateViewLayout(view, layoutParams)
                }
                else -> {}
            }
            false
        }