Android项目实战（二十六）：蓝牙连接硬件设备开发规范流程

前言：

　　最近接触蓝牙开发，主要是通过蓝牙连接获取传感器硬件设备的数据，并进行处理。

　　网上学习一番，现整理出一套比较标准的 操作流程代码。

　　如果大家看得懂，将来只需要改下 硬件设备的MAC码 和 改下对接收数据的处理 即可。  一切都是套路~~~

现在以一个小型项目需求来学习Android蓝牙编程

需求： 通过蓝牙获取硬件数据，并显示在一个随数据即时变化的动态折线图中。

实现思路：

（1） 配对蓝牙设备  

（2） 连接蓝牙设备    ，根据MAC地址，代码中修改

（3） 接收数据

（4） 处理数据          ，根据硬件厂商提供给你的数据转换公式，在BluetoothService类中 修改

（5） 传数据给折线图，展现实时变化

-----------------------------------------------------------------------

蓝牙知识了解：

（1）、MAC地址：每个设备都有全球唯一的，根据此MAC地址判断蓝牙设备

（2）、蓝牙传输数据，通常一秒钟会传输很多个包，每个包的数据情况如下：

　　此时，这个包有11个字节，0x55 是首码，通常通过他来判断一个包的开始

　　                                   SUM是验证码，会有一套公式来计算，判断当前包是不是一个有效的完整的包

　　　　　　　　　　　　　　中间的即是数据，然后硬件方面会给我们一套计算公式，可以以此获取我们要的数据。

　　当然每个硬件的包的数据大小都是不同的，有的可能有21个字节，每个硬件的数据的计算方式也不想同

代码实现：

一共就三部分，因为代码篇幅可能较大，不适合一段段代码讲解，直接贴出整个代码。所有的解释都在注释当中。

其中：

（1）、红色部分是需要大家根据个人硬件情况进行修改的

（2）、紫色部分是根据个人数据情况添加删除修改的。

一：MainActivity

public class MainActivity extends Activity {

    private BluetoothService mBluetoothService; //自定义蓝牙服务类
    private BluetoothAdapter mBluetoothAdapter;
    private String mConnectedDeviceName = null; //连接设备的名称

    //默认是1,因为程序启动时首先会连接一个蓝牙
    private int current_pos = 1;

    //hanlder消息标识 message.what
    public static final int MESSAGE_STATE_CHANGE = 1; // 状态改变
    public static final int MESSAGE_READ = 2;          // 读取数据
    public static final int MESSAGE_WRITE = 3;         // 给硬件传数据，暂不需要，看具体需求
    public static final int MESSAGE_DEVICE_NAME = 4;  // 设备名字
    public static final int MESSAGE_TOAST = 5;         // Toast

    //传感器 ,这里默认同时需要和三个硬件连接，分别设置id 1,2,3进行区分，demo中实际只用到 MAGIKARE_SENSOR_DOWN = 1
    //可以根据情况自行添加删除
    public static final int MAGIKARE_SENSOR_UP = 2;
    public static final int MAGIKARE_SENSOR_DOWN = 1;
    public static final int MAGIKARE_SENSOR_CENTER = 3;

    public static float[] m_receive_data_up;                    //传感器的数据
    public static float[] m_receive_data_down;                  //传感器的数据 ,demo中我们只需要这一个，因为只有一个硬件设备，
    public static float[] m_receive_data_center;                //传感器的数据


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //获取蓝牙适配器
        mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();

        // 1、判断设备是否支持蓝牙功能
        if (mBluetoothAdapter == null) {
            //设备不支持蓝牙功能
            Toast.makeText(this, "当前设备不支持蓝牙功能！", Toast.LENGTH_SHORT).show();
            return;
        }

        // 2、打开设备的蓝牙功能
        if (!mBluetoothAdapter.isEnabled()) {
            boolean enable = mBluetoothAdapter.enable(); //返回值表示 是否成功打开了蓝牙设备
            if (enable) {
                Toast.makeText(this, "打开蓝牙功能成功！", Toast.LENGTH_SHORT).show();
            } else {
                Toast.makeText(this, "打开蓝牙功能失败，请到'系统设置'中手动开启蓝牙功能！", Toast.LENGTH_SHORT).show();
                return;
            }
        }


        // 3、创建自定义蓝牙服务对象
        if (mBluetoothService == null) {
            mBluetoothService = new BluetoothService(MainActivity.this, mHandler);
        }
        if (mBluetoothService != null) {
            //根据MAC地址远程获取一个蓝牙设备，这里固定了，实际开发中，需要动态设置参数（MAC地址）
            BluetoothDevice sensor_down = mBluetoothAdapter.getRemoteDevice("20:16:06:15:78:76");
            if (sensor_down != null) {
                //成功获取到远程蓝牙设备（传感器），这里默认只连接MAGIKARE_SENSOR_DOWN = 1这个设备
                mBluetoothService.connect(sensor_down, MAGIKARE_SENSOR_DOWN);
            }
        }


    }
    private Handler mHandler = new Handler(new Handler.Callback() {
        @Override
        public boolean handleMessage(Message msg) {
            switch (msg.what){
                case MESSAGE_READ:
                    try {
                        String str=msg.getData().getString("index");
                        int index=Integer.valueOf(str);
                        switch (index)
                        {
                            //获取到蓝牙传输过来的数据
                            case MAGIKARE_SENSOR_UP:
                                m_receive_data_up=msg.getData().getFloatArray("Data");
                                break;
                            //实际只用到这个case ，因为demo只连接了一个硬件设备
                            case MAGIKARE_SENSOR_DOWN:
                                m_receive_data_down=msg.getData().getFloatArray("Data");
                                break;
                            case MAGIKARE_SENSOR_CENTER:
                                m_receive_data_center=msg.getData().getFloatArray("Data");
                                break;

                        }
                    } catch (Exception e) {
                        // TODO: handle exception
                    }
                    break;
                case MESSAGE_STATE_CHANGE:
//                    连接状态
                    switch (msg.arg1) {
                        case BluetoothService.STATE_CONNECTED:
                            break;
                        case BluetoothService.STATE_CONNECTING:
                            break;
                        case BluetoothService.STATE_LISTEN:
                            break;
                        case BluetoothService.STATE_NONE:
                            break;
                    }
                    break;
                case MESSAGE_DEVICE_NAME:
                    mConnectedDeviceName = msg.getData().getString("device_name");
                    Log.i("bluetooth","成功连接到:"+mConnectedDeviceName);
                    Toast.makeText(getApplicationContext(),"成功连接到设备" + mConnectedDeviceName,Toast.LENGTH_SHORT).show();

                    break;
                case MESSAGE_TOAST:
                    int index=msg.getData().getInt("device_id");
                    Toast.makeText(getApplicationContext(),msg.getData().getString("toast"), Toast.LENGTH_SHORT).show();
                    //当失去设备或者不能连接设备时，重新连接
                    Log.d("Magikare","当失去设备或者不能连接设备时，重新连接");
　　　　　　　　　　　　
　　　　　　　　　　　　//重新连接硬件设备
                    if(mBluetoothService!=null)
                    {
                        switch (index) {
                            case MAGIKARE_SENSOR_DOWN:
　　　　　　　　　　　　　　　　　　　　//根据你的硬件的MAC地址写参数，每一个硬件设备都有一个MAC地址，此方法是根据MAC地址得到蓝牙设备
                                BluetoothDevice sensor_down = mBluetoothAdapter.getRemoteDevice("20:16:06:15:78:76");
                                if (sensor_down != null)
                                    mBluetoothService.connect(sensor_down, MAGIKARE_SENSOR_DOWN);
                                break;
                            case MAGIKARE_SENSOR_UP:
                                BluetoothDevice sensor_up = mBluetoothAdapter.getRemoteDevice("");  //参数写你这个设备的MAC码
                                if (sensor_up != null)
                                    mBluetoothService.connect(sensor_up, MAGIKARE_SENSOR_UP);
                                break;
                            case MAGIKARE_SENSOR_CENTER:
                                BluetoothDevice center = mBluetoothAdapter.getRemoteDevice("");    //参数写你这个设备的MAC码
                                if (center != null)
                                    mBluetoothService.connect(center, MAGIKARE_SENSOR_CENTER);
                                break;
                        }
                    }

                    break;
            }
            return false;
        }
    });





    public synchronized void onResume() {
        super.onResume();

        if (mBluetoothService != null) {
            if (mBluetoothService.getState() == BluetoothService.STATE_NONE) {
                mBluetoothService.start();
            }
        }
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        if (mBluetoothService != null) mBluetoothService.stop();
    }
　　
　　
　　// 硬件通过蓝牙传输的byte类型已经转换为float类型，并且通过handler传输到 m_receive_data_down[]数组中，一下操作是获取这个数据，根据个人情况使用
    //获取角度
    public float[] GetAngle(int index)
    {
        float[] angles=new float[3];
        if(m_receive_data_up==null
                ||m_receive_data_down==null
                )
        {
            return angles;
        }
        switch (index)
        {
            case  MAGIKARE_SENSOR_DOWN:
                angles[0]=m_receive_data_down[6];
                angles[1]=m_receive_data_down[7];
                angles[2]=m_receive_data_down[8];
                break;
            case MAGIKARE_SENSOR_UP:
                angles[0]=m_receive_data_up[6];
                angles[1]=m_receive_data_up[7];
                angles[2]=m_receive_data_up[8];
                Log.d("安卓 Up 角度",angles[0]+","+angles[1]+","+angles[2]);
                break;
        }
        return angles;
    }
    //获取角速度
    public static float[] GetAngleSpeed(int index)
    {

        float [] anglespeed=new float[3];

        if(m_receive_data_down==null)
        {

            return anglespeed;
        }
        switch (index)
        {
            case MAGIKARE_SENSOR_DOWN:

                anglespeed[0]=m_receive_data_down[3];
                anglespeed[1]=m_receive_data_down[4];
                anglespeed[2]=m_receive_data_down[5];
                break;
            case MAGIKARE_SENSOR_UP:
                anglespeed[0]=m_receive_data_up[3];
                anglespeed[1]=m_receive_data_up[4];
                anglespeed[2]=m_receive_data_up[5];
                break;
        }
        return  anglespeed;
    }

    public float[] GetQuaternion(int index)
    {
        float[] quaternion=new float[4];

        if(m_receive_data_down==null)
        {
            return quaternion;
        }
        switch (index)
        {
            case  MAGIKARE_SENSOR_DOWN:
                quaternion[0]=m_receive_data_down[23];
                quaternion[1]=m_receive_data_down[24];
                quaternion[2]=m_receive_data_down[25];
                quaternion[3]=m_receive_data_down[26];
                Log.i("saveinfo","m_receive_data_down23"+m_receive_data_down[23]);
                Log.i("saveinfo","m_receive_data_down24"+m_receive_data_down[24]);
                Log.i("saveinfo","m_receive_data_down25"+m_receive_data_down[25]);
                Log.i("saveinfo","m_receive_data_down26"+m_receive_data_down[26]);
                break;
            case MAGIKARE_SENSOR_UP:
                quaternion[0]=m_receive_data_up[23];
                quaternion[1]=m_receive_data_up[24];
                quaternion[2]=m_receive_data_up[25];
                quaternion[3]=m_receive_data_up[26];
                break;
            case MAGIKARE_SENSOR_CENTER:
                quaternion[0]=m_receive_data_center[23];
                quaternion[1]=m_receive_data_center[24];
                quaternion[2]=m_receive_data_center[25];
                quaternion[3]=m_receive_data_center[26];
        }
        return  quaternion;
    }



}

二、BluetoothService

public class BluetoothService {
　　private static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
    private Context context;
    //蓝牙适配器
    private BluetoothAdapter mAdapter;
    private Handler mHandler;

    //当前传感器设备的个数，即要开启的线程个数，用于设置线程数组的大小
    //这里默认为1，因为我们目前只需要和一个传感器连接， 比如：你要连接两个硬件设备，那就设置值为2，这样就会开启两个线程，分别去执行想要操作
    public static final int  SENSEOR_NUM=1;

    private AcceptThread mAcceptThread;// 请求连接的监听进程
    private ConnectThread mConnectThread;// 连接一个设备的进程
    public ConnectedThread[] mConnectedThread=new ConnectedThread[SENSEOR_NUM];// 已经连接之后的管理进程

    private int mState;// 当前状态

    // 指明连接状态的常量
    public static final int STATE_NONE = 0;         //没有连接
    public static final int STATE_LISTEN = 1;       //等待连接
    public static final int STATE_CONNECTING = 2;  //正在连接
    public static final int STATE_CONNECTED = 3;   //已经连接

    public BluetoothService(Context context, Handler mHandler) {
        this.context = context;
        this.mHandler = mHandler;
        mAdapter = BluetoothAdapter.getDefaultAdapter();//获取蓝牙适配器
        mState = STATE_NONE ; //当前连接状态：未连接
    }

    // 参数 index 是 硬件设备的id ，随便设的，目的在于当 同时连接多个硬件设备的时候，根据此id进行区分
    public synchronized void connect(BluetoothDevice device, int index) {

        //连接一个蓝牙时，将该设备 的蓝牙连接线程关闭，如果有的话
        //demo  就只有一个硬件设备，默认该设备id 取值index=1;
        if (mConnectedThread[index-1] != null) {
            mConnectedThread[index-1].cancel();
            mConnectedThread[index-1]=null;
        }
        mConnectThread=new ConnectThread(device,index);
        mConnectThread.start();
        setState(STATE_CONNECTING);
    }

    private class ConnectThread extends Thread{
        private final BluetoothSocket mmSocket;
        private final BluetoothDevice mmDevice;
        private int index;
        public ConnectThread(BluetoothDevice device,int index) {
            mmDevice = device;
            this.index=index;
            BluetoothSocket tmp = null;
            try {
                tmp = device.createRfcommSocketToServiceRecord(MY_UUID);// Get a BluetoothSocket for a connection with the given BluetoothDevice
            }
            catch (IOException e) {}
            mmSocket = tmp;
        }

        public void run() {

            setName("ConnectThread");
            //当连接成功，取消蓝牙适配器搜索蓝牙设备的操作，因为搜索操作非常耗时
            mAdapter.cancelDiscovery();// Always cancel discovery because it will slow down a connection

            try {
                mmSocket.connect();// This is a blocking call and will only return on a successful connection or an exception
            }
            catch (IOException e) {
                connectionFailed(this.index);
                try {
                    mmSocket.close();
                } catch (IOException e2) {}

                BluetoothService.this.start();// 引用来说明要调用的是外部类的方法 run
                return;
            }

            synchronized (BluetoothService.this) {// Reset the ConnectThread because we're done
                mConnectThread = null;
            }
            connected(mmSocket, mmDevice,index);// Start the connected thread
        }

        public void cancel() {
            try {
                mmSocket.close();
            } catch (IOException e) {
            }
        }
    }

    class ConnectedThread extends Thread{
        private BluetoothSocket mmSocket;
        private InputStream mmInStream;
        private OutputStream mmOutStream;
        private int index;
        private Queue<Byte> queueBuffer = new LinkedList<Byte>();
        private byte[] packBuffer = new byte[11];


        //构造方法
        public ConnectedThread(BluetoothSocket socket,int index) {
            mmSocket = socket;
            InputStream tmpIn = null;
            OutputStream tmpOut = null;
            this.index=index;
            // Get the BluetoothSocket input and output streams
            try {
                tmpIn = socket.getInputStream();
                tmpOut = socket.getOutputStream();
            } catch (IOException e) {}

            mmInStream = tmpIn;
            mmOutStream = tmpOut;
        }

        // 数组大小看你的数据需求，这里存的是你处理蓝牙传输来的字节数据之后实际要用到的数据
        private float [] fData=new float[31];

        @Override
        public void run() {
            byte[] tempInputBuffer = new byte[1024];
            int acceptedLen = 0; //记录每次读取数据的数据长度
            byte sHead;
            long lLastTime = System.currentTimeMillis(); //获取开始时间
            while(true){
                try {
                    acceptedLen = mmInStream.read(tempInputBuffer);//返回接收的长度
                    //从缓冲区中读取数据
                    for (int i = 0; i < acceptedLen; i++) {
                        queueBuffer.add(tempInputBuffer[i]);
                    }
                    // 这里需要按个人硬件数据的情况自行修改了
                    // 如果你的硬件蓝牙传输 一个包有11个字节，那queueBuffer.size()>=11
                    // 如果你的硬件蓝牙传输 一个包有21个字节，那queueBuffer.size()>=21
                    while (queueBuffer.size()>=11){
                        //返回队首并删除，判断队首是不是0x55，如果不是，说明不是一个包的数据，跳过，
                        //注意这里的0x55是你的包的首字节
                        if (queueBuffer.poll()!=0x55)
                            continue;
                        // 进入到这里，说明得到一个包的数据了，然后就要根据个人硬件的数据情况，将byte类型的数据转换为float类型的数据

                        sHead = queueBuffer.poll(); //返回队首并删除
　　　　　　　　
　　　　　　　　　　　　　　// 现在得到的就是你数据部分了，如果有9位字节代表数据，j<9 ，如果有19位字节代表数据，j<19
　　　　　　　　　　　　　　　　　
　　　　　　　　　　　　　　//将字节数组存到packBuffer[]数据中，用于byte-->float数据的转换
                        for (int j = 0; j < 9; j++) {
                            packBuffer[j] = queueBuffer.poll();
                        }
                        switch (sHead) {//
                            case 0x52://角速度
                                fData[3] = ((((short) packBuffer[1]) << 8) | ((short) packBuffer[0] & 0xff)) /  2000;
                                fData[4] = ((((short) packBuffer[3]) << 8) | ((short) packBuffer[2] & 0xff)) /  200;
                                fData[5] = ((((short) packBuffer[5]) << 8) | ((short) packBuffer[4] & 0xff)) /  200;
                                fData[17] = ((((short) packBuffer[7]) << 8) | ((short) packBuffer[6] & 0xff)) / 100.0f;
                                break;
                            case 0x53://角度
                                fData[6] = ((((short) packBuffer[1]) << 8) | ((short) packBuffer[0] & 0xff)) /  180;
                                fData[7] = ((((short) packBuffer[3]) << 8) | ((short) packBuffer[2] & 0xff)) /  180;
                                fData[8] = ((((short) packBuffer[5]) << 8) | ((short) packBuffer[4] & 0xff)) /  180;
                                fData[17] = ((((short) packBuffer[7]) << 8) | ((short) packBuffer[6] & 0xff)) / 100.0f;
                                break;
                            case 0x59://四元数
                                fData[23] = ((((short) packBuffer[1]) << 8) | ((short) packBuffer[0] & 0xff)) / 327.0f;
                                fData[24] = ((((short) packBuffer[3]) << 8) | ((short) packBuffer[2] & 0xff)) /327.0f;
                                fData[25] = ((((short) packBuffer[5]) << 8) | ((short) packBuffer[4] & 0xff)) /327.0f;
                                fData[26] = ((((short) packBuffer[7]) << 8) | ((short) packBuffer[6] & 0xff)) /327.0f;
                                break;
                        }
                    }
                    long lTimeNow = System.currentTimeMillis(); // 获取收据转换之后的时间
                    // 如果数据处理后的时间  与 接收到数据的时间 的时间差>80 则发送消息传输数据，
                    // 这个时间需要看你硬件一秒钟发送的包的个数
                    if (lTimeNow - lLastTime > 80) {
                        lLastTime = lTimeNow;
                        Message msg = mHandler.obtainMessage(MainActivity.MESSAGE_READ);
                        Bundle bundle = new Bundle();
                        bundle.putString("index",String.valueOf(this.index));
                        bundle.putFloatArray("Data", fData);
                        msg.setData(bundle);
                        mHandler.sendMessage(msg);
                    }
                } catch (IOException e) {
                    connectionLost(this.index);
                    e.printStackTrace();
                }
            }
        }
        public void cancel() {
            try {
                mmSocket.close();
            } catch (IOException e) {}
        }
    }
    //连接失败
    private void connectionFailed(int index) {
        setState(STATE_LISTEN);
        // Send a failure message back to the Activity
        Message msg = mHandler.obtainMessage(MainActivity.MESSAGE_TOAST);
        Bundle bundle = new Bundle();
        bundle.putString("toast", "未能连接设备"+index);
        bundle.putInt("device_id",index);
        msg.setData(bundle);
        mHandler.sendMessage(msg);
    }
    // 连接丢失
    private void connectionLost(int index) {
        setState(STATE_LISTEN);
        Message msg = mHandler.obtainMessage(MainActivity.MESSAGE_TOAST);
        Bundle bundle = new Bundle();
        bundle.putString("toast", "设备丢失"+index);
        bundle.putInt("device_id",index);
        msg.setData(bundle);
        mHandler.sendMessage(msg);
    }


    //用于 蓝牙连接的Activity onResume()方法
    public synchronized void start() {
        // Cancel any thread attempting to make a connection
        if (mConnectThread != null) {
            mConnectThread.cancel();
            mConnectThread = null;
        }

        if (mAcceptThread == null) {
            mAcceptThread = new AcceptThread();
            mAcceptThread.start();
        }
        setState(STATE_LISTEN);
    }

    public synchronized void connected(BluetoothSocket socket,BluetoothDevice device,int index) {
        Log.d("MAGIKARE","连接到线程"+index);
        // Cancel the thread that completed the connection
        if (mConnectThread != null) {
            mConnectThread.cancel();
            mConnectThread = null;
        }
        // Cancel the accept thread because we only want to connect to one device
        if (mAcceptThread != null) {
            mAcceptThread.cancel();
            mAcceptThread = null;
        }

        // Start the thread to manage the connection and perform transmissions
        mConnectedThread[index-1] = new ConnectedThread(socket,index);

        mConnectedThread[index-1].start();

        // Send the name of the connected device back to the UI Activity
        Message msg = mHandler.obtainMessage(MainActivity.MESSAGE_DEVICE_NAME);
        Bundle bundle = new Bundle();
        bundle.putString("device_name", device.getName()+" "+index);

        msg.setData(bundle);
        mHandler.sendMessage(msg);

        setState(STATE_CONNECTED);
    }

    private synchronized void setState(int state) {
        mState = state;
        // Give the new state to the Handler so the UI Activity can update
        mHandler.obtainMessage(MainActivity.MESSAGE_STATE_CHANGE, state, -1).sendToTarget();
    }

    private class AcceptThread extends Thread {
        // The local server socket
        private final BluetoothServerSocket mmServerSocket;
        //private int index;
        public AcceptThread() {
            BluetoothServerSocket tmp = null;
            // this.index=index;
            // Create a new listening server socket
            try {
                tmp = mAdapter.listenUsingRfcommWithServiceRecord("BluetoothData", MY_UUID);
            }
            catch (IOException e) {}
            mmServerSocket = tmp;
        }

        public void run() {
            new Thread(new Runnable() {
                @Override
                public void run() {

                }
            }).start();

        }

        public void cancel() {

            try {
                if(mmServerSocket!=null) {
                    mmServerSocket.close();
                }
            }
            catch (IOException e) {}
        }
    }
    public synchronized int getState() {
        return mState;
    }


    public synchronized void stop() {
        if (mConnectedThread != null) {
            for(int i=0;i<mConnectedThread.length;i++)
            {
                    mConnectedThread[i].cancel();
            }
            mConnectedThread = null;
        }
        if (mAcceptThread != null) {
            mAcceptThread.cancel();
            mAcceptThread = null;
        }
        setState(STATE_NONE);
    }
}

三、自定义即时变化的折线图：

public class MyView extends View {
    /*http://www.cnblogs.com/aibuli/p/950c34f2bc0d02cbd290dd6a8339d42a.html*/
    //坐标轴原点的位置
    private int xPoint=60;
    private int yPoint=260;
    //刻度长度
    private int xScale=8;  //8个单位构成一个刻度
    private int yScale=40;
    //x与y坐标轴的长度
    private int xLength=580;
    private int yLength=480;

    private int MaxDataSize=xLength/xScale;   //横坐标  最多可绘制的点

    private List<Float> data=new ArrayList<Float>();   //存放 纵坐标 所描绘的点

    private String[] yLabel=new String[yLength/yScale];  //Y轴的刻度上显示字的集合


    private Handler mh=new Handler(){
        public void handleMessage(android.os.Message msg) {
            if(msg.what==0){                //判断接受消息类型
                MyView.this.invalidate();  //刷新View
            }
        };
    };
    public MyView(Context context, AttributeSet attrs) {
        super(context, attrs);
        for (int i = 0; i <yLabel.length; i++) {
            yLabel[i]=(i+1)+"M/s";
        }
        new Thread(new Runnable() {
            @Override
            public void run() {
                while(true){     //在线程中不断往集合中增加数据
                    try {
                        Thread.sleep(300);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    if(data.size()>MaxDataSize){  //判断集合的长度是否大于最大绘制长度
                        data.remove(0);  //删除头数据
                    }
                    // 这里得到蓝牙设备得到的数据
                    float[] floats = MainActivity.GetAngleSpeed(1);
                    data.add(floats[0]);
                    mh.sendEmptyMessage(0);   //发送空消息通知刷新
                }
            }
        }).start();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        Paint paint=new Paint();
        paint.setStyle(Paint.Style.STROKE);
        paint.setAntiAlias(true);
        paint.setColor(Color.RED);
        //绘制Y轴
        canvas.drawLine(xPoint, yPoint-yLength, xPoint, yPoint, paint);
        //绘制Y轴左右两边的箭头
        canvas.drawLine(xPoint, yPoint-yLength, xPoint-3,yPoint-yLength+6, paint);
        canvas.drawLine(xPoint, yPoint-yLength, xPoint+3,yPoint-yLength+6, paint);
        //Y轴上的刻度与文字
        for (int i = 0; i * yScale< yLength; i++) {
            canvas.drawLine(xPoint, yPoint-i*yScale, xPoint+5, yPoint-i*yScale, paint);  //刻度
            canvas.drawText(yLabel[i], xPoint-50, yPoint-i*yScale, paint);//文字
        }
        //X轴
        canvas.drawLine(xPoint, yPoint, xPoint+xLength, yPoint, paint);
        //如果集合中有数据
        if(data.size()>1){
            for (int i = 1; i < data.size(); i++) {  //依次取出数据进行绘制
                canvas.drawLine(xPoint+(i-1)*xScale, yPoint-data.get(i-1)*yScale, xPoint+i*xScale, yPoint-data.get(i)*yScale, paint);
            }
        }

    }
}

相关知识：浅谈Bluetooth蓝牙开发

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