Android 如何使用广播接收器检测蓝牙状态变化？
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How to detect Bluetooth state change using a broadcast receiver?
提问by Mohammad H
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.
我正在尝试制作一个在设备的蓝牙打开时显示吐司的应用程序。即使我的应用程序没有运行，我也想这样做。所以我应该使用一个广播接收器，添加一些权限，一个意图过滤器到 android manifest 并创建一个 java 类，但我不知道细节。
What should I do? Which permissions should I use?
我该怎么办？我应该使用哪些权限？
回答by paNji
AS far as permissions go, to detect the state change of bluetooth you need to add this to your AndroidManifest.xml.
就权限而言，要检测蓝牙的状态变化，您需要将其添加到您的 AndroidManifest.xml 中。
<uses-permission android:name="android.permission.BLUETOOTH" />
An example receiver would look like this, you add this code to where you want to handle the broadcast, for example an activity:
示例接收器如下所示，您将此代码添加到要处理广播的位置，例如活动：
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
public void onReceive (Context context, Intent intent) {
String action = intent.getAction();
if (BluetoothAdapter.ACTION_STATE_CHANGED.equals(action)) {
if(intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, -1)
== BluetoothAdapter.STATE_OFF)
// Bluetooth is disconnected, do handling here
}
}
};
To use the receiver, you need to register it. Which you can do as follows. I register the receiver in my main activity.
要使用接收器，您需要注册它。您可以执行以下操作。我在我的主要活动中注册接收器。
registerReceiver(this, new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED));
You could also decide to add all of it to your AndroidManifest.xml. This way you can make a special class for the receiver and handle it there. No need to register the receiver, just make the class and add the below code to the AndroidManifest
您也可以决定将所有这些添加到您的 AndroidManifest.xml 中。这样你就可以为接收器创建一个特殊的类并在那里处理它。无需注册接收器，只需创建类并将以下代码添加到AndroidManifest
<receiver
android:name=".packagename.NameOfBroadcastReceiverClass"
android:enabled="true">
<intent-filter>
<action android:name="android.bluetooth.adapter.action.STATE_CHANGED"/>
</intent-filter>
</receiver>
回答by Manikanta Ottiprolu
You have to take following permission.
您必须获得以下许可。
<uses-permission android:name="android.permission.BLUETOOTH" />
and you have to write this as your intent filter in receiver tag.
并且您必须将其写为接收者标签中的意图过滤器。
<action android:name="android.bluetooth.adapter.action.STATE_CHANGED" />
回答by Nicola Gallazzi
Unfortunately, for apps targeting api 26or higher, manifest declared broadcast receivers don't work anymore (reference here: https://developer.android.com/guide/components/broadcast-exceptions), with some exceptions.
android.bluetooth.adapter.action.STATE_CHANGEDis not in that list.
不幸的是，对于面向api 26或更高版本的应用程序，清单声明的广播接收器不再工作（参考此处：https: //developer.android.com/guide/components/broadcast-exceptions），但有一些例外。
android.bluetooth.adapter.action.STATE_CHANGED不在那个列表中。
For bluetooth, you can only listen for changes on:
对于蓝牙，您只能监听以下更改：
ACTION_CONNECTION_STATE_CHANGED, ACTION_ACL_CONNECTED, ACTION_ACL_DISCONNECTED
ACTION_CONNECTION_STATE_CHANGED, ACTION_ACL_CONNECTED,ACTION_ACL_DISCONNECTED
