如何定期扫描蓝牙设备在Android

Question

你好，这听起来是一个愚蠢的question.But我无法找到这个任何答案，所以在这里发帖。

我正在构建一个室内应用程序，它可以连续扫描位于商场或图书馆等地的不同位置的蓝牙适配器。当我在商场中移动手机时，我应该能够找到最近的加密狗我可以连接到（愚蠢的想法，但我想要做这件事）。为此，我应该能够不断扫描蓝牙设备。

请能有人告诉我我该如何使Android定期扫描可用的蓝牙设备。

Answer 1

我想这是如此简单，但没有之前打我。下面是答案，

private BluetoothAdapter mBtAdapter; 
mBtAdapter.startDiscovery(); 

private final BroadcastReceiver mReceiver = new BroadcastReceiver() 
{ 
     @Override 
     public void onReceive(Context context, Intent intent) 
     { 
      String action = intent.getAction(); 

      // When discovery finds a device 
      if (BluetoothDevice.ACTION_FOUND.equals(action)) 
      { 
      //do something 
      } 

      else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) 
      { 
       Log.v(TAG,"Entered the Finished "); 
       mBtAdapter.startDiscovery(); 
      } 

因此，我们应该再次ACTION_DISCOVERY_FINISHED这将持续每12秒设备扫描开始发现。

Answer 2

您的代码段应该努力 - 只是它会在电力消耗方面是昂贵的，肯定会杀了你的设备/电话在几个小时。 startDiscovery（）执行两个步骤的过程，通过查询找到设备，然后发现名称，即寻呼并连接到设备，但不幸的是，Android不提供任何API来控制此操作，只做查询，也有大多数蓝牙芯片组定义和支持的定期查询功能，Android目前没有任何API来进行定期查询，可能对您的使用情况更为理想。

Answer 3

这里是让所有有效的蓝牙设备列表中的代码[成对或非成对]

import java.util.Set; 

import android.app.Activity; 
import android.bluetooth.BluetoothAdapter; 
import android.bluetooth.BluetoothDevice; 
import android.content.BroadcastReceiver; 
import android.content.Context; 
import android.content.Intent; 
import android.content.IntentFilter; 
import android.os.Bundle; 
import android.util.Log; 
import android.view.View; 
import android.view.Window; 
import android.view.View.OnClickListener; 
import android.widget.AdapterView; 
import android.widget.ArrayAdapter; 
import android.widget.Button; 
import android.widget.ListView; 
import android.widget.TextView; 
import android.widget.AdapterView.OnItemClickListener; 

/** 
* This Activity appears as a dialog. It lists any paired devices and 
* devices detected in the area after discovery. When a device is chosen 
* by the user, the MAC address of the device is sent back to the parent 
* Activity in the result Intent. 
*/ 
public class DeviceListActivity extends Activity { 
    // Debugging 
    private static final String TAG = "DeviceListActivity"; 
    private static final boolean D = true; 

    // Return Intent extra 
    public static String EXTRA_DEVICE_ADDRESS = "device_address"; 

    // Member fields 
    private BluetoothAdapter mBtAdapter; 
    private ArrayAdapter<String> mPairedDevicesArrayAdapter; 
    private ArrayAdapter<String> mNewDevicesArrayAdapter; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 

     // Setup the window 
     requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS); 
     setContentView(R.layout.activity_device_list); 


     // Initialize the button to perform device discovery 
     Button scanButton = (Button) findViewById(R.id.button_scan); 
     scanButton.setOnClickListener(new OnClickListener() { 
      public void onClick(View v) { 
       doDiscovery(); 
       v.setVisibility(View.GONE); 
      } 
     }); 

     // Initialize array adapters. One for already paired devices and 
     // one for newly discovered devices 
     mPairedDevicesArrayAdapter = new ArrayAdapter<String>(this, R.layout.device_name); 
     mNewDevicesArrayAdapter = new ArrayAdapter<String>(this, R.layout.device_name); 

     // Find and set up the ListView for paired devices 
     ListView pairedListView = (ListView) findViewById(R.id.paired_devices); 
     pairedListView.setAdapter(mPairedDevicesArrayAdapter); 
     pairedListView.setOnItemClickListener(mDeviceClickListener); 

     // Find and set up the ListView for newly discovered devices 
     ListView newDevicesListView = (ListView) findViewById(R.id.new_devices); 
     newDevicesListView.setAdapter(mNewDevicesArrayAdapter); 
     newDevicesListView.setOnItemClickListener(mDeviceClickListener); 

     // Register for broadcasts when a device is discovered 
     IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND); 
     this.registerReceiver(mReceiver, filter); 

     // Register for broadcasts when discovery has finished 
     filter = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED); 
     this.registerReceiver(mReceiver, filter); 

     // Get the local Bluetooth adapter 
     mBtAdapter = BluetoothAdapter.getDefaultAdapter(); 

     // Get a set of currently paired devices 
     Set<BluetoothDevice> pairedDevices = mBtAdapter.getBondedDevices(); 

     // If there are paired devices, add each one to the ArrayAdapter 
     if (pairedDevices.size() > 0) { 
      findViewById(R.id.title_paired_devices).setVisibility(View.VISIBLE); 
      for (BluetoothDevice device : pairedDevices) { 
       mPairedDevicesArrayAdapter.add(device.getName() + "\n" + device.getAddress()); 
      } 
     } else { 
      String noDevices = getResources().getText(R.string.none_paired).toString(); 
      mPairedDevicesArrayAdapter.add(noDevices); 
     } 
    } 

    @Override 
    protected void onDestroy() { 
     super.onDestroy(); 

     // Make sure we're not doing discovery anymore 
     if (mBtAdapter != null) { 
      mBtAdapter.cancelDiscovery(); 
     } 
     // Unregister broadcast listeners 
     this.unregisterReceiver(mReceiver); 
    } 

    /** 
    * Start device discover with the BluetoothAdapter 
    */ 
    private void doDiscovery() { 
     if (D) Log.d(TAG, "doDiscovery()"); 

     // Indicate scanning in the title 
     setProgressBarIndeterminateVisibility(true); 
     setTitle(R.string.scanning); 

     // Turn on sub-title for new devices 
     findViewById(R.id.title_new_devices).setVisibility(View.VISIBLE); 

     // If we're already discovering, stop it 
     if (mBtAdapter.isDiscovering()) { 
      mBtAdapter.cancelDiscovery(); 
     } 
     // Request discover from BluetoothAdapter 
     mBtAdapter.startDiscovery(); 
    } 

    // The on-click listener for all devices in the ListViews 
    private OnItemClickListener mDeviceClickListener = new OnItemClickListener() { 
     public void onItemClick(AdapterView<?> av, View v, int i, long l) { 
      // Cancel discovery because it's costly and we're about to connect 
      mBtAdapter.cancelDiscovery(); 

      // Get the device MAC address, which is the last 17 chars in the View 
      String info = ((TextView) v).getText().toString(); 
      String address = info.substring(info.length() - 17); 


     } 
    }; 

    // The BroadcastReceiver that listens for discovered devices and 
    // changes the title when discovery is finished 
    private final BroadcastReceiver mReceiver = new BroadcastReceiver() { 
     @Override 
     public void onReceive(Context context, Intent intent) { 
      String action = intent.getAction(); 

      // When discovery finds a device 
      if (BluetoothDevice.ACTION_FOUND.equals(action)) { 
       // Get the BluetoothDevice object from the Intent 
       BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE); 
       // If it's already paired, skip it, because it's been listed already 
       if (device.getBondState() != BluetoothDevice.BOND_BONDED) { 
        mNewDevicesArrayAdapter.add(device.getName() + "\n" + device.getAddress()); 
       } 
      // When discovery is finished, change the Activity title 
      } else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) { 
       setProgressBarIndeterminateVisibility(false); 
       setTitle(R.string.select_device); 
       if (mNewDevicesArrayAdapter.getCount() == 0) { 
        String noDevices = getResources().getText(R.string.none_found).toString(); 
        mNewDevicesArrayAdapter.add(noDevices); 
       } 
      } 
     } 
    }; 

} 

我从API演示的想法，我希望这可能是所有开发人员有用。

Answer 4

如documentation中所述，设备发现是一个高级过程，将直接降低您与其他设备之间所有绑定的性能。

小心：执行设备发现对于 蓝牙适配器来说是一个沉重的过程，并且会消耗大量资源。一旦您找到要连接的设备，请确保在尝试连接之前始终使用cancelDiscovery（）停止 发现。另外，如果您已与设备保持连接，则执行 发现可显着减少可用于 连接的带宽，因此您不应在连接时执行发现。

考虑到这一点（省略处理错误）：

private final BroadcastReceiver deviceBroadcastReceiver = new BroadcastReceiver() { 
     @Override 
     public void onReceive(Context context, Intent intent) { 
      String action = intent.getAction(); 

      if (BluetoothDevice.ACTION_FOUND.equals(action)) { 
       deviceFound = true; 

       adapter.cancelDiscovery(); 

       //process new device. 

       deviceFound = false; 

       adapter.startDiscovery(); 
      } 
} 

private final BroadcastReceiver adapterBroadcastReceiver = new BroadcastReceiver() { 
     @Override 
     public void onReceive(Context context, Intent intent) { 
      String action = intent.getAction(); 

      if (BluetoothAdaptor.ACTION_DISCOVERY_FINISHED.equals(action)) { 
       if (deviceFound == false) { 
         adapter.startDiscovery(); 
       } 
      } 
}