Android中的蓝牙设备发现 - startDiscovery()

Question

目标:构建一个Android应用程序,发现范围内BT设备的名称和地址,并将其值提交给Web服务.以前没有将BT设备绑定到主机设备,我只是想在我走动时查看所有内容.

我做了什么:

1. 仔细阅读文档.
2. 实现了主机设备的BT适配器的本地实例.
3. 如果未启用BT,则实施启用BT的通知.
4. 注册的广播接收者和意图来解析startDiscovery()的ACTION_FOUNDs即将到来.
5. 清单中注册的BLUETOOTH和BLUETOOTH_ADMIN权限.

事情起作用(使用增量控制台记录测试)直到startDiscovery().

挫折:

• startDiscovery() - 我怀疑我在错误的上下文中传递它.该方法需要在什么上下文中才能正常运行？

如果你能够使用这种方法,我将非常感谢你的智慧.

更新 - 这是一个简化的代码简化版本,让我感到悲伤; 这种简化概括了我的错误.此代码运行,它不会抛出任何cat.log错误或其他错误,它根本不提供任何输出.

package aqu.bttest;

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.widget.Toast;

public class BT2Activity extends Activity {

private BluetoothAdapter mBTA;
private SingBroadcastReceiver mReceiver;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

  //register local BT adapter
    mBTA = BluetoothAdapter.getDefaultAdapter();
    //check to see if there is BT on the Android device at all
    if (mBTA == null){
        int duration = Toast.LENGTH_SHORT;
        Toast.makeText(this, "No Bluetooth on this handset", duration).show();
    }
    //let's make the user enable BT if it isn't already
    if (!mBTA.isEnabled()){
        Intent enableBT = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
        startActivityForResult(enableBT, 0xDEADBEEF);
    }
    //cancel any prior BT device discovery
    if (mBTA.isDiscovering()){
        mBTA.cancelDiscovery();
    }
    //re-start discovery
    mBTA.startDiscovery();

    //let's make a broadcast receiver to register our things
    mReceiver = new SingBroadcastReceiver();
    IntentFilter ifilter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
    this.registerReceiver(mReceiver, ifilter);
}

private class SingBroadcastReceiver extends BroadcastReceiver {

    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction(); //may need to chain this to a recognizing function
        if (BluetoothDevice.ACTION_FOUND.equals(action)){
            // Get the BluetoothDevice object from the Intent
            BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
            // Add the name and address to an array adapter to show in a Toast
            String derp = device.getName() + " - " + device.getAddress();
            Toast.makeText(context, derp, Toast.LENGTH_LONG);
        }
    }
}

}

Answer 1

该方法需要在什么上下文中才能正常运行.

简单来说,您应该startDiscovery()在希望应用程序发现本地蓝牙设备时使用...例如,如果您想实施ListActivity扫描并动态添加附近的蓝牙设备ListView(请参阅参考资料DeviceListActivity).

您对该startDiscovery()方法的使用应如下所示:

1. 定义表示本地蓝牙适配器的类变量.

   BluetoothAdapter mBtAdapter = BluetoothAdapter.getDefaultAdapter();
   

2. 检查您的设备是否已"发现".如果是,则取消发现.

   if (mBtAdapter.isDiscovering()) {
       mBtAdapter.cancelDiscovery();
   }
   

3. 检查(并可能取消)发现模式后,立即通过调用启动发现,

   mBtAdapter.startDiscovery();
   

4. 一般要非常小心,不小心将设备置于发现模式.执行设备发现对于蓝牙适配器来说是一个繁重的过程,并且会消耗大量资源.例如,您要确保在尝试建立连接之前检查/取消发现.您很可能也希望在onDestroy方法中取消发现.

如果这有帮助,请告诉我......如果您仍然遇到问题,请使用您的logcat输出和/或您收到的任何错误消息更新您的答案,也许我可以帮助您更多.