蓝牙项目开发心得

一，发射器情况：有1个Service，Service下有2个Characteristic,其中1个Characteristic命名为writeCharacteristic（FFF1)具有read,write 2个属性，另外1个Characteristic命名为notifyCharacteristic(FFF2)具有notify属性

以上信息可以在获得Characteristic后用日志查看，代码如下：writeCharacteristic的Properties返回10，说明具有 PROPERTY_READ(和PROPERTY_WRITE （8）

for (BluetoothGattCharacteristic gattCharacteristic : gattCharacteristics) {
    uuidCharac = gattCharacteristic.getUuid().toString();
    if (writeCharacUUID.equals(uuidCharac) ){
        mWiriteCharacteristic=gattCharacteristic;
        System.out.println("s-2 myCharacter + uuid=" + uuidCharac);
        System.out.println("s-3 myCharacter + toString=" + gattCharacteristic.toString());
        System.out.println("s-3 myCharacter + Permissions=" + gattCharacteristic.getPermissions());
        System.out.println("s-3 myCharacter + Properties=" + gattCharacteristic.getProperties());
        System.out.println("s-3 myCharacter + WriteType=" + gattCharacteristic.getWriteType());
        System.out.println("s-3 myCharacter + Value=" + gattCharacteristic.getValue());
        charas.add(gattCharacteristic);
    }
   else if(notifyCharaUUID.equals(uuidCharac)) {
        mNotifyCharacteristic=gattCharacteristic;
        System.out.println("s-2 myCharacter + uuid=" + uuidCharac);
        System.out.println("s-3 myCharacter + toString=" + gattCharacteristic.toString());
        System.out.println("s-3 myCharacter + Permissions=" + gattCharacteristic.getPermissions());
        System.out.println("s-3 myCharacter + Properties=" + gattCharacteristic.getProperties());
        System.out.println("s-3 myCharacter + WriteType=" + gattCharacteristic.getWriteType());
        System.out.println("s-3 myCharacter + Value=" + gattCharacteristic.getValue());
        charas.add(gattCharacteristic);
    }
}
输出结果如下：
08-14 07:59:02.626 15236-15236/com.klt.kamin.cgmbasedemo I/System.out: s-1 myServices + uuid=0000fff0-0000-1000-8000-00805f9b34fb
08-14 07:59:02.627 15236-15236/com.klt.kamin.cgmbasedemo I/System.out: s-2 myCharacter + uuid=0000fff1-0000-1000-8000-00805f9b34fb
08-14 07:59:02.627 15236-15236/com.klt.kamin.cgmbasedemo I/System.out: s-3 myCharacter + toString=android.bluetooth.BluetoothGattCharacteristic@dee0c13
08-14 07:59:02.627 15236-15236/com.klt.kamin.cgmbasedemo I/System.out: s-3 myCharacter + Permissions=0
08-14 07:59:02.627 15236-15236/com.klt.kamin.cgmbasedemo I/System.out: s-3 myCharacter + Properties=10
08-14 07:59:02.627 15236-15236/com.klt.kamin.cgmbasedemo I/System.out: s-3 myCharacter + WriteType=2
08-14 07:59:02.627 15236-15236/com.klt.kamin.cgmbasedemo I/System.out: s-3 myCharacter + Value=null
08-14 07:59:02.627 15236-15236/com.klt.kamin.cgmbasedemo I/System.out: s-2 myCharacter + uuid=0000fff2-0000-1000-8000-00805f9b34fb
08-14 07:59:02.627 15236-15236/com.klt.kamin.cgmbasedemo I/System.out: s-3 myCharacter + toString=android.bluetooth.BluetoothGattCharacteristic@fbb1e50
08-14 07:59:02.627 15236-15236/com.klt.kamin.cgmbasedemo I/System.out: s-3 myCharacter + Permissions=0
08-14 07:59:02.627 15236-15236/com.klt.kamin.cgmbasedemo I/System.out: s-3 myCharacter + Properties=16
08-14 07:59:02.627 15236-15236/com.klt.kamin.cgmbasedemo I/System.out: s-3 myCharacter + WriteType=2
08-14 07:59:02.627 15236-15236/com.klt.kamin.cgmbasedemo I/System.out: s-3 myCharacter + Value=null

二，任务：手机APP中输入指定命令，发送后，发射器会把执行结果返回到手机APP上显示

1蓝牙连接成功后，把所有Characteristic查找到

2执行下面代码使能notifyCharacteristic的notify， 将会在此通道(FFF2)产生有关命令操作的执行结果通知。

mSCharacteristic=mNotifyCharacteristic;
mBluetoothLeService.setCharacteristicNotification(mNotifyCharacteristic, true);

3执行代码writeCharacteristic对通道FFF1进行写命令操作,每产生一次采集结果后，将会在FFF2通道产生一个 notify 通知事件，附带了本次采集结果, APP 可以直接在回调函数中进行处理和使用。

public void serialSend(String theString){
System.out.println("w-2-1 In CgmLibrary.serialSend(serialSendText),mConnectionState="+mConnectionState.toString());
if (mConnectionState == connectionStateEnum.isConnected) {    
    mSCharacteristic=mWiriteCharacteristic;
    mSCharacteristic.setValue(Conversion.hexStringToByteArray(theString));//写之前必须把输入的命令转换为十六进制字符串
    mBluetoothLeService.writeCharacteristic(mSCharacteristic);   
}}
 mBluetoothLeService.writeCharacteristic(mSCharacteristic)代码如下：
 public void writeCharacteristic(BluetoothGattCharacteristic characteristic) {
if (mBluetoothAdapter == null || mBluetoothGatt == null) {
    Log.w(TAG, "BluetoothAdapter not initialized");
    return;
}
mBluetoothGatt.writeCharacteristic(characteristic);}
System.out.println("w-3-1 In BluetoothLeService.writeCharacteristic(characteristic)---->before mBluetoothGatt.writeCharacteristic(characteristic)/**********" );
mBluetoothGatt.writeCharacteristic(characteristic);如果把命令成功写到发射器，会触发：
BluetoothGattCallback的  onCharacteristicWrite方法：这个方法没有做任何事情可以删除掉
  public void onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status)
        {
            System.out.println("w-5 in onCharacteristicWrite,buttonSerialSend-->serialSend->writeCharacteristic-->status="+status);
            //this block should be synchronized to prevent the function overloading
            synchronized(this)
            {    //CharacteristicWrite success
                if(status == BluetoothGatt.GATT_SUCCESS)
                {
                    System.out.println(" w-6 in onCharacteristicWrite-status == BluetoothGatt.GATT_SUCCESS--characteristicValue:"+ new String(Conversion.byteArrayToHexStr(characteristic.getValue())));
                }
                else     //CharacteristicWrite fail
                {
                    System.out.println("w-7 onCharacteristicWrite fail:"+ new String(characteristic.getValue()));
                    System.out.println(status);
                }
            }
        }
每产生一次采集结果后，将会在FFF2通道产生一个 notify 通知事件，附带了本次采集结果,
APP 可以直接在回调函数onCharacteristicChanged中进行处理和使用。处理完的结果通过广播返回到界面或者保存到数据库
  @Override
    public void onCharacteristicChanged(BluetoothGatt gatt,
                                        BluetoothGattCharacteristic characteristic) {
        System.out.println("w-5-1 In BluetoothLeService.onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic)/$$$$$$$$$$$$");
        System.out.println("w-5-2 onCharacteristicChanged characValue return from emmiter="+characteristic.getValue());
        System.out.println("w-5-2 onCharacteristicChanged characValue return from emmiter with HexString=" + Conversion.byteArrayToHexStr(characteristic.getValue()));
        System.out.println("w-5-2 onCharacteristicChanged characValue return from emmiter with new String=" + new String(characteristic.getValue()));
        broadcastUpdate(ACTION_DATA_AVAILABLE, characteristic);
        System.out.println("w-5-1 In BluetoothLeService.onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic)$$$$$$$$$$$$/");
    }
}
  private void broadcastUpdate(final String action,
                                 final BluetoothGattCharacteristic characteristic) {
        System.out.println("w-6-1 In BluetoothLeService.broadcastUpdate(String action, BluetoothGattCharacteristic characteristic)，action=ACTION_DATA_AVAILABLE/@@@@@@@@@@@");
        final Intent intent = new Intent(action);
        final byte[] data = characteristic.getValue();
        if (data != null && data.length > 0) {
            if(Conversion.verifyCommand(data)){
            System.out.println("w-6-2 after Verify and Success in broadcastUpdate,only data,cut first byte and last byte--->DATAascii:"+Conversion.getDataToPrint(data));
            intent.putExtra(EXTRA_DATA,Conversion.getDataToPrint(data));
            }
            sendBroadcast(intent);
        }
        System.out.println("w-6-1 In BluetoothLeService.broadcastUpdate(String action, BluetoothGattCharacteristic characteristic),action=ACTION_DATA_AVAILABLE@@@@@@@@@@@/");
    }

4要考虑十六进制转换

(1)输入的命令转换为十六进制字节数组

mSCharacteristic.setValue(Conversion.hexStringToByteArray(theString));
mBluetoothLeService.writeCharacteristic(mSCharacteristic);

在App输入框中输入执行命令：0155AA00这是个字符串，并不代表你的真实目的，你是把这个字符串看成4个字节的16进制形式的命令：00000001  01010101  10101010  00000000，但由于是String类型，计算机中每个字符是1个字节，所以计算机把你的输入当作11个字节的数据00000000 00000001 00000101 00000101 00001010 00001010 00000000 00000000，显然这是错误的，所以，首先需要把你输入的十六进制形式的命令转换为字节数组，代码如下：

/**
  * Convert hex String to Byte Array
  * example:String str="43474D"; byte[] result=Conversion.hexStringToByteArray(str); for(byte b:result) System.out.print(b+" ");
  * System.out.println(); System.out.println("byteArry to StringAscii----"+new String(result));
  * example result    67 71 77 
  *       byteArry to StringAscii----CGM
  * @param hexString
  * @return byte[]
  */
 public static byte[] hexStringToByteArray(String hexString) {
  hexString=hexString.toUpperCase();
  hexString=hexString.replace(" ", "");
  int len = (hexString.length() / 2);
  byte[] result = new byte[len];
  char[] achar = hexString.toCharArray();
  for (int i = 0; i < len; i++) {
   int pos = i * 2;
   result[i] = (byte) (toByte(achar[pos]) << 4 | toByte(achar[pos + 1]));
  }
  return result;
 }

（2）获取到的数据需要进行处理

三、执行结果

08-15 23:16:22.287 13742-13742/com.klt.kamin.cgmbasedemo I/System.out: w-1 in MainActivity.onCreate()-->serialSend(serialSendText)/****************************************
08-15 23:16:22.287 13742-13742/com.klt.kamin.cgmbasedemo I/System.out: w-2-1 In CgmLibrary.serialSend(serialSendText),mConnectionState=isConnected
08-15 23:16:22.287 13742-13742/com.klt.kamin.cgmbasedemo I/System.out: w-2-2 CgmLibrary.serialSend(serialSendText),OLD  mSCharacteristicUUID=0000fff2-0000-1000-8000-00805f9b34fb
08-15 23:16:22.287 13742-13742/com.klt.kamin.cgmbasedemo I/System.out: w-2-2 CgmLibrary.serialSend(serialSendText),NOW NEW mSCharacteristicUUID=0000fff1-0000-1000-8000-00805f9b34fb
08-15 23:16:22.289 13742-13742/com.klt.kamin.cgmbasedemo I/System.out: w-2-3 CgmLibrary.serialSend(serialSendText),mSCharacteristicWriteValueHex=0155AA00
08-15 23:16:22.289 13742-13742/com.klt.kamin.cgmbasedemo I/System.out: w-2-3 CgmLibrary.serialSend(serialSendText),mSCharacteristicWriteValueByte=[B@bbc67ba
08-15 23:16:22.289 13742-13742/com.klt.kamin.cgmbasedemo I/System.out: w-2-4 In CgmLibrary.serialSend(serialSendText)---->mBluetoothLeService.writeCharacteristic(mSCharacteristic)/********************
08-15 23:16:22.290 13742-13742/com.klt.kamin.cgmbasedemo I/System.out: w-3-1 In BluetoothLeService.writeCharacteristic(characteristic)---->before mBluetoothGatt.writeCharacteristic(characteristic)/**********
08-15 23:16:22.292 13742-13742/com.klt.kamin.cgmbasedemo I/System.out: w-3-2 In BluetoothLeService.writeCharacteristic(characteristic)---->after mBluetoothGatt.writeCharacteristic(characteristic)**********/
08-15 23:16:22.292 13742-13742/com.klt.kamin.cgmbasedemo I/System.out: w-2-4 In CgmLibrary.serialSend(serialSendText)---->after mBluetoothLeService.writeCharacteristic(mSCharacteristic)********************/
08-15 23:16:22.292 13742-13742/com.klt.kamin.cgmbasedemo I/System.out: w-1 in MainActivity.onCreate() after serialSend()****************************************/
08-15 23:16:23.413 13742-13755/com.klt.kamin.cgmbasedemo I/System.out: w-5-1 In BluetoothLeService.onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic)/$$$$$$$$$$$$
08-15 23:16:23.416 13742-13755/com.klt.kamin.cgmbasedemo I/System.out: w-5-2 onCharacteristicChanged characValue return from emmiter=[B@aaf066b
08-15 23:16:23.417 13742-13755/com.klt.kamin.cgmbasedemo I/System.out: w-5-2 onCharacteristicChanged characValue return from emmiter with HexString=01 53 4E 30 36 31 36 30 30 35 30 34 
08-15 23:16:23.417 13742-13755/com.klt.kamin.cgmbasedemo I/System.out: w-5-2 onCharacteristicChanged characValue return from emmiter with String=�SN061600504
08-15 23:16:23.417 13742-13755/com.klt.kamin.cgmbasedemo I/System.out: w-6-1 In BluetoothLeService.broadcastUpdate(String action, BluetoothGattCharacteristic characteristic)，action=ACTION_DATA_AVAILABLE/@@@@@@@@@@@
08-15 23:16:23.418 13742-13755/com.klt.kamin.cgmbasedemo I/System.out: w-6-2 after Verify and Success in broadcastUpdate,only data,cut first byte and last byte--->dataByteWithHex:53 4E 30 36 31 36 30 30 35 30 
08-15 23:16:23.418 13742-13755/com.klt.kamin.cgmbasedemo I/System.out: w-6-2 after Verify and Success in broadcastUpdate,only data,cut first byte and last byte--->dataAscii:SN06160050
08-15 23:16:23.418 13742-13755/com.klt.kamin.cgmbasedemo I/SendBroadcastPermission: action:com.example.bluetooth.le.ACTION_DATA_AVAILABLE, mPermissionType:0
08-15 23:16:23.420 13742-13755/com.klt.kamin.cgmbasedemo I/System.out: w-6-1 In BluetoothLeService.broadcastUpdate(String action, BluetoothGattCharacteristic characteristic),action=ACTION_DATA_AVAILABLE@@@@@@@@@@@/
08-15 23:16:23.420 13742-13755/com.klt.kamin.cgmbasedemo I/System.out: w-5-1 In BluetoothLeService.onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic)$$$$$$$$$$$$/
08-15 23:16:23.421 13742-13742/com.klt.kamin.cgmbasedemo I/System.out: mGattUpdateReceiver->onReceive->action=com.example.bluetooth.le.ACTION_DATA_AVAILABLE
08-15 23:16:23.421 13742-13742/com.klt.kamin.cgmbasedemo I/System.out: w-7-1 In CgmLibrary.BroadcastReceiver.onReceive(Context context, Intent intent),action=ACTION_DATA_AVAILABLE/&&&&&&&&&
08-15 23:16:23.421 13742-13742/com.klt.kamin.cgmbasedemo I/System.out: w-7-1 in BroadcastReceiver, writeuuid=0000fff1-0000-1000-8000-00805f9b34fb
08-15 23:16:23.422 13742-13742/com.klt.kamin.cgmbasedemo I/System.out: w-7-1 displayData: SN06160050
08-15 23:16:23.422 13742-13742/com.klt.kamin.cgmbasedemo I/System.out: w-8 In MainActivity.onSerialReceived
08-15 23:16:23.429 13742-13742/com.klt.kamin.cgmbasedemo I/System.out: w-7-1 In CgmLibrary.BroadcastReceiver.onReceive(Context context, Intent intent),action=ACTION_DATA_AVAILABLE&&&&&&&&&/

四、以上任务卡了3天做不出来，主要原因如下：

1，不清楚每个Characteristic的属性，fff1可读可写,fff2Notify，可以按一查看

2，不清楚流程：

（1）先使能notifyCharacteristic（二、2）

（2）对发射器进行write命令操作（二、3）

（3）子BluetoothGattCallback的onCharacteristicChanged方法里对发射器返回的数据进行处理。

mBluetoothGatt.writeCharacteristic(characteristic);如果把命令成功写到发射器，会触发：
BluetoothGattCallback的  onCharacteristicWrite方法，这里面不做什么可以不用要
执行代码writeCharacteristic对通道FFF1进行写命令操作,每产生一次采集结果后，
将会在FFF2通道产生一个 notify 通知事件，附带了本次采集结果, APP 可以直接在回调函数中进行处理和使用。

3，写到mSCharacteristic的值没有转成十六进制字符串（二、4）导致写进去的值是错误的

五、扫描广播、连接、绑定

1，Android手机为central,GATT client；发射器为peripheral,GATT server

Central vs. peripheral:  中心设备和外围设备的概念针对的是BLE连接本身。Central角色负责scan advertisement。而peripheral角色负责make advertisement。

GATT server vs. GATT client:这两种角色取决于BLE连接成功后，两个设备间通信的方式。两个设备通过BLE通信，首先需要建立GATT连接。这里我们讲的是Android设备作为client端，连接GATT Server。

 问：Client和Server节点是如何定义呢？

答：通俗地说吧，Server（服务器）就是数据中心，Client（客户端）就是访问数据者。特别说明，它与主/从设备是独立的概念：一个主设备既可以充当Server，又可以充当Client；从设备亦然。

为了安全起见，一些数据的访问需要认证，它的完成是这样的：一方（可以是主节点，也可以是从节点）向另一方索要6位数字的密码，之后，两个节点彼此交换安全密钥用于加密和认证，此过程称为配对。认证的过程比较繁琐，BLE协议支持两节点保存认证的安全密钥（一般是非易失性存储器中），以便于两节点下次连接后快速认证，这就是绑定技术

BLE蓝牙4.0经典问答【转】 - 逗不过奇葩 - 博客园  最清晰的关于蓝牙ble的解答，适合初学者