如何使用广播接收器检测蓝牙状态变化？

I am trying to make an app that shows a toast when the device's Bluetooth turned on. I wanna do that even when my app is not running. So I should use a broadcast receiver, add some permissions, an intent-filter to android manifest and make a java class but I don't know the details.I am trying to make an app that shows a toast w