尝试使用本地访问在android中实现蓝牙功能,但在设备上启动应用程序时,本地访问变量似乎为空。需要帮助来弄清楚为什么会发生这种情况,以及如何解决它。谢谢
这些是我的构建提示

StateMachine类中的用法示例
BTNative nativeBT = (BTNative)NativeLookup.create(BTNative.class);
@Override
protected void onMain_ScanButtonAction(Component c, ActionEvent event) {
super.onMain_ScanButtonAction(c, event);
try {
if (nativeBT != null && nativeBT.isSupported()) {
try {
nativeBT.findBT();
nativeBT.openBT();
} catch (Throwable t) {
Dialog.show("Error", "Exception during findBT and openBT access: " + t, "OK", null);
}
}else{
Dialog.show("Error", "Can't get native access", "OK", null);
}
} catch (Throwable t) {
Dialog.show("Error", "Exception during native access: " + t, "OK", null);
}
}NativeImpl
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Set;
import java.util.UUID;
import android.widget.Toast;公共类BTNativeImpl{
//android built in classes for bluetooth operations
BluetoothAdapter mBluetoothAdapter;
BluetoothSocket mmSocket;
BluetoothDevice mmDevice;
//needed for communication to bluetooth device / network
OutputStream mmOutputStream;
InputStream mmInputStream;
Thread workerThread;
byte[] readBuffer;
int readBufferPosition;
volatile boolean stopWorker;
public void closeBT() {
try {
stopWorker = true;
mmOutputStream.close();
mmInputStream.close();
mmSocket.close();
} catch (Exception e) {
e.printStackTrace();
}
}
//this will send text data to be printed by the bluetooth printer
public void sendData(String param){
try {
// the text typed by the user
param += "\n";
mmOutputStream.write(param.getBytes());
// tell the user data were sent
} catch (Exception e) {
e.printStackTrace();
}
}
//this will find a bluetooth printer device
public void findBT() {
try {
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (mBluetoothAdapter == null) {
Toast.makeText(com.codename1.impl.android.AndroidNativeUtil.getActivity(), "No bluetooth adapter available", Toast.LENGTH_LONG).show();
}
if (!mBluetoothAdapter.isEnabled()) {
Intent enableBluetooth = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
com.codename1.impl.android.AndroidNativeUtil.getActivity().startActivityForResult(enableBluetooth, 0);
}
Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
if (pairedDevices.size() > 0) {
for (BluetoothDevice device : pairedDevices) {
if (device.getName().equals("BlueTooth Printer")) {
mmDevice = device;
break;
}
}
}
Toast.makeText(com.codename1.impl.android.AndroidNativeUtil.getActivity(), "Bluetooth device found.", Toast.LENGTH_LONG).show();
} catch (Exception e) {
e.printStackTrace();
}
}
public void openBT() {
try {
//Standard SerialPortService ID
UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb");
mmSocket = mmDevice.createRfcommSocketToServiceRecord(uuid);
mmSocket.connect();
mmOutputStream = mmSocket.getOutputStream();
mmInputStream = mmSocket.getInputStream();
beginListenForData();
Toast.makeText(com.codename1.impl.android.AndroidNativeUtil.getActivity(), "Bluetooth Opened", Toast.LENGTH_LONG).show();
} catch (Exception e) {
e.printStackTrace();
}
}
public void beginListenForData() {
try {
final Handler handler = new Handler();
//this is the ASCII code for a newline character
final byte delimiter = 10;
stopWorker = false;
readBufferPosition = 0;
readBuffer = new byte[1024];
workerThread = new Thread(new Runnable() {
public void run() {
while (!Thread.currentThread().isInterrupted() && !stopWorker) {
try {
int bytesAvailable = mmInputStream.available();
if (bytesAvailable > 0) {
byte[] packetBytes = new byte[bytesAvailable];
mmInputStream.read(packetBytes);
for (int i = 0; i < bytesAvailable; i++) {
byte b = packetBytes[i];
if (b == delimiter) {
byte[] encodedBytes = new byte[readBufferPosition];
System.arraycopy(readBuffer, 0, encodedBytes, 0, encodedBytes.length);
// specify US-ASCII encoding
final String data = new String(encodedBytes, "US-ASCII");
readBufferPosition = 0;
// tell the user data were sent to bluetooth printer device
handler.post(new Runnable() {
public void run() {
Toast.makeText(com.codename1.impl.android.AndroidNativeUtil.getActivity(), data, Toast.LENGTH_LONG).show();
}
});
} else {
readBuffer[readBufferPosition++] = b;
}
}
}
} catch (IOException ex) {
stopWorker = true;
}
}
}
});
workerThread.start();
} catch (Exception e) {
e.printStackTrace();
}
}
public boolean isSupported() {
return true;
}}
发布于 2016-07-26 02:10:05
您可能还需要BLUETOOTH_ADMIN权限。我不确定这是否是唯一的问题,但肯定会带来问题。
来自Android的开发者指南:
https://developer.android.com/guide/topics/connectivity/bluetooth.html#Permissions
在将impl类的继承更改为派生Activity时,您还犯了一个大错误!
您需要创建一个单独的activity类,并在创建impl类和Android创建activity类时分别注册它,两者是不同的。我建议看看其他cn1libs,它们大多数都是开源的,看看这是如何做到的。我还建议用电缆连接您的设备,并在ddms中查看输出以跟踪问题。
https://stackoverflow.com/questions/38568447
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