判断当前手机蓝牙是否开启

private BluetoothAdapter adapter;
private BroadcastReceiver receiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
//接收蓝牙状态变化的广播
String action = intent.getAction();
//发现蓝牙设备
BluetoothDevice device=intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
if (action.equals(BluetoothDevice.ACTION_FOUND)) {
String name=   device.getName();
} else if (action.equals(BluetoothDevice.ACTION_BOND_STATE_CHANGED)) {
//可以在监听到蓝牙状态是进行操作
switch (device.getBondState()){
case BluetoothDevice.BOND_BONDED:
//已经配对成功
break;
case BluetoothDevice.BOND_BONDING:
//正在连接
break;
case BluetoothDevice.BOND_NONE:
//取消连接
break;
default:
break;
}
}
}
};

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//蓝牙连接设备增加
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
//蓝牙连接状态发生改变
filter.addAction(BluetoothDevice.ACTION_BOND_STATE_CHANGED);
//注册
registerReceiver(receiver, filter);
//获取蓝牙适配器
adapter  = BluetoothAdapter.getDefaultAdapter();
boolean isenable = adapter.isEnabled();
System.out.println(isenable + "<-=-=-=-isenable");
//获取蓝牙是否可用
Toast.makeText(MainActivity.this, isenable + "<-=-=-=-isenable", Toast.LENGTH_SHORT).show();
if (!adapter.isEnabled()) {
//开启蓝牙
adapter.enable();
} else {
Intent intent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
//设置你自己的设备可以被其他设备搜索的时间；最大3600
intent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);
startActivity(intent);
}
//蓝牙设备的地址
String address = adapter.getAddress();
String name = adapter.getName();
Log.d("蓝牙", "name=" + name + "  address=" + address);
//获取通过蓝牙已经连接的设备
Set<BluetoothDevice> list = adapter.getBondedDevices();
if (list != null) {
for (BluetoothDevice device : list) {
//设备名称
String dname = device.getName();
}
}
//搜索其他设备
new Thread() {
@Override
public void run() {
super.run();
//正在搜索状态
if (adapter.isDiscovering()) {
adapter.cancelDiscovery();
}
//开始搜索其他设备；
adapter.startDiscovery();
}
}.start();
}

@Override
protected void onDestroy() {
super.onDestroy();
unregisterReceiver(receiver);
}