藍牙基本的連接流程：
隨着可穿戴設備的流行，研究藍牙是必不可少的一門技術了。
藍牙權限
首先需要AndroidManifest.xml文件中添加操作藍牙的權限。
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mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter(); // 獲取藍牙適配器
Set<BluetoothDevice> devices = mBluetoothAdapter.getBondedDevices(); // 查找配對歷史
if(devices.size() == 0){
ToastUtil.showShort("請與打印機的藍牙匹配好！");
isBluetooth = false;
//return;
}else{
if (mBluetoothAdapter == null) {
Toast.makeText(this, "您的設備不支持藍牙", 0).show();
return;
}
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
this.registerReceiver(mReceiver, filter);
filter = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
this.registerReceiver(mReceiver, filter);
mBtAdapter = BluetoothAdapter.getDefaultAdapter();
Set<BluetoothDevice> pairedDevices = mBtAdapter.getBondedDevices();
if (pairedDevices.size() > 0) {
for (BluetoothDevice device : pairedDevices) {
Log.i("設備",device.getName() + "\n" + device.getAddress());
lanya=device.getName() + "\n" + device.getAddress();
}
}
mBtAdapter.cancelDiscovery();
String address=lanya.substring(lanya.length() - 17);
if (!mBluetoothAdapter.isEnabled()) {
Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableIntent, REQUEST_ENABLE_BT);
}
if (mService==null) {
mService = new BluetoothService(this, mHandler);
}
BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(address);
mService.connect(device);
}
private final Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MESSAGE_STATE_CHANGE:
switch (msg.arg1) {
case BluetoothService.STATE_CONNECTED:
Log.i("開始",mConnectedDeviceName+"開開");
// Log.i("鏈接",mConnectedDeviceName+"123456789");
// print_connect_btn.append(mConnectedDeviceName);
break;
case BluetoothService.STATE_CONNECTING:
Log.i("開始連接","正在連接...");
break;
case BluetoothService.STATE_LISTEN:
case BluetoothService.STATE_NONE:
Log.i("ceroor","無連接");
break;
}
break;
case MESSAGE_WRITE:
//byte[] writeBuf = (byte[]) msg.obj;
// construct a string from the buffer
//String writeMessage = new String(writeBuf);
break;
case MESSAGE_READ:
//byte[] readBuf = (byte[]) msg.obj;
// construct a string from the valid bytes in the buffer
//String readMessage = new String(readBuf, 0, msg.arg1);
break;
case MESSAGE_DEVICE_NAME:
// save the connected device's name
mConnectedDeviceName = msg.getData().getString(DEVICE_NAME);
break;
case MESSAGE_TOAST:
ToastUtil.showShort("沒發現打印機設備，請退出！");
showLY();
break;
}
}
};
private AdapterView.OnItemClickListener mDeviceClickListener = new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> av, View v, int arg2, long arg3) {
String info = ((TextView) v).getText().toString();
String address = info.substring(info.length() - 17);
}
};
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
@SuppressLint("MissingPermission")
@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("選擇連接的設備");
}
}
};
// 根據手機屏幕大小截屏生成圖片
public void viewSaveToImage(View view) {
view.setDrawingCacheEnabled(true);
view.setDrawingCacheQuality(View.DRAWING_CACHE_QUALITY_HIGH);
view.setDrawingCacheBackgroundColor(Color.WHITE);
// 把一個View轉換成圖片
Bitmap cachebmp = loadBitmapFromView(view);
// 添加水印
Bitmap bitmap = Bitmap.createBitmap(createWatermarkBitmap(cachebmp,
""));
FileOutputStream fos;
try {
// 判斷手機設備是否有SD卡
boolean isHasSDCard = Environment.getExternalStorageState().equals(
Environment.MEDIA_MOUNTED);
if (isHasSDCard) {
// SD卡根目錄
File sdRoot = Environment.getExternalStorageDirectory();
File file = new File(sdRoot, "gao.png");
fos = new FileOutputStream(file);
} else
throw new Exception("創建文件失敗!");
bitmap.compress(Bitmap.CompressFormat.PNG, 90, fos);
fos.flush();
fos.close();
} catch (Exception e) {
e.printStackTrace();
}
view.destroyDrawingCache();
}
private Bitmap loadBitmapFromView(View v) {
int w = 500;
int h = 385;
Bitmap bmp = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
Canvas c = new Canvas(bmp);
c.drawColor(Color.WHITE);
/** 如果不設置canvas畫布爲白色，則生成透明 */
v.layout(0, 0, w, h);
v.draw(c);
return bmp;
}
// 爲圖片target添加水印
private Bitmap createWatermarkBitmap(Bitmap target, String str) {
int w = target.getWidth();
int h = target.getHeight();
Bitmap bmp = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(bmp);
Paint p = new Paint();
// 水印的顏色
p.setColor(Color.RED);
// 水印的字體大小
p.setTextSize(16);
p.setAntiAlias(true);// 去鋸齒
canvas.drawBitmap(target, 0, 0, p);
// 在中間位置開始添加水印
canvas.drawText(str, w / 2, h / 2, p);
canvas.save(Canvas.ALL_SAVE_FLAG);
canvas.restore();
return bmp;
}
// 把圖片轉成二進制發送給熱敏打印機
try{
RelativeLayout layout = new LoadAlert(PoWeighActivity.this,relative,"打印中..").getLoadAlert();
String path= Environment.getExternalStorageDirectory()+"/gao.png";
File mFile=new File(path);
//若該文件存在
Bitmap bitmap = null;
if (mFile.exists()) {
bitmap= BitmapFactory.decodeFile(path);
}
sendMessage(bitmap,layout);
}catch (Exception e){
ToastUtil.showShort("打印失敗！");
e.printStackTrace();
}