BLE 扫描回调的类加载期间的 NoClassDefFoundError

Posted 2023-03-05

【中文标题】BLE 扫描回调的类加载期间的 NoClassDefFoundError

【英文标题】：NoClassDefFoundError during class load for BLE scanning callback

【发布时间】：2014-04-28 11:47:50

【问题描述】：

当我的课程被加载时，我会不断收到NoClassDefFoundError。

代码取自 BluetoothLeGatt 项目 -

http://developer.android.com/samples/BluetoothLeGatt/project.html

我的代码：

// Device scan callback.
private BluetoothAdapter.LeScanCallback mLeScanCallback = 
    new BluetoothAdapter.LeScanCallback()  //java.lang.NoClassDefFoundError...

    @Override
    public void onLeScan(final BluetoothDevice device, 
    final int rssi, final byte[] scanRecord) 
        runOnUiThread(new Runnable() 
            @Override
            public void run()              
                String msg= device.getAddress();

                Log.d(TAG,msg);
                addItems(msg);
            
        );
    
;

有人建议该错误是因为我的设备不支持 BLE，但我想为任何设备消除此错误。因此，如果它不支持 BLE 功能，则只需跳过此错误，否则继续调用此 BluetoothAdapter.LeScanCallback。

注意：

请参阅this我以前的 SO 帖子以获得更多说明。

将 BLE 功能检查作为第一行 onCreate() 并不能阻止崩溃 --

@Override
    public void onCreate(Bundle savedInstanceState) 

    if (!bleCheck()) 
          Toast.makeText(getApplicationContext(), R.string.ble_not_supported,  
          Toast.LENGTH_SHORT).show();
          finish();
    

        //Rest of the code
        //Call to BLE Scan on button click that causes error..
    



 private boolean bleCheck() 
        boolean result = false;     
        if (getPackageManager().
            hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE))
             result = true;
        
        return result;
      

【问题讨论】：

希望答案对您有所帮助，Android 的 BLE 目前还很棘手，一直在努力

【参考方案1】：

BluetoothAdapter.LeScanCallback 是 在 API 级别 18 中添加的 ； Source，此代码还需要 API 级别检查。以下是我的处理方式，没有将回调声明为私有，而是在以下条件下：

boolean apiJBorAbove = android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.JELLY_BEAN_MR2 ? true
                : false;

boolean isBleAvailable = getPackageManager().hasSystemFeature(
                PackageManager.FEATURE_BLUETOOTH_LE) ? true : false;


// Use this check to determine whether BLE is supported on the device.
if (isBleAvailable && apiJBorAbove) 
// Initializes a Bluetooth adapter.
// For API level 18 and above, get a reference to
// BluetoothAdapter through BluetoothManager.
final BluetoothManager bluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
            mBluetoothAdapter = bluetoothManager.getAdapter();

// Ensures Bluetooth is available on the device and it is enabled.
// If not, displays a dialog requesting user permission to enable
// Bluetooth.
if (mBluetoothAdapter == null || !mBluetoothAdapter.isEnabled()) 
                startActivity(new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE));
            

BluetoothAdapter.LeScanCallback mLeScanCallback = 
    new BluetoothAdapter.LeScanCallback() 

    @Override
    public void onLeScan(final BluetoothDevice device, 
                    final int rssi, final byte[] scanRecord) 
                        runOnUiThread(new Runnable() 
                            @Override
                            public void run()              
                                String msg= device.getAddress();
//                              Log.d(TAG,msg);
//                              addItems(msg);
                            
                        );
                    
                ;
          

NoClassDefFoundError是由于API，而不是基于PackageManager.FEATURE_BLUETOOTH_LE。

【讨论】：

啊，非常感谢。你不知道你节省了多少时间。

欢迎，很高兴它有帮助，如果您遇到其他问题，请告诉我

当然，android 中的 BLE 对我来说非常新。如果卡住了会通知你。谢谢！

我一直坚持通过 BLE 发送命令。让我知道您是否可以提供帮助 - ***.com/questions/23393010/…

检查我的答案和参考项目，将帮助您理解