flutter调用原生实现连接控制称重设备

最近接了一个新需求：

内容： 通过手机app实现蓝牙连接称重设备，实现app获取设备重量并接入业务

语言以及工具：

        1、flutter  + java安卓原生      

        2、某某牌蓝牙称重蓝牙硬件板块（称榜上拆下来的）：

前面走过的坑（只对于我接手的项目而已，并不是说以下文档插件不好）：

1、flutter_weigh_serial 1.0.0+2

这个插件我试了，但是和我的gradle版本不兼容，就被我舍弃了

2、bluetooth_print  这个热敏蓝牙打印插件我也试了，可以搜索到该蓝牙设备，但是连接不了

 最后没办法，还是老老实实写原生方法

1、建立flutter与原生通道

new MethodChannel(Objects.requireNonNull(getFlutterEngine()).getDartExecutor().getBinaryMessenger(), WEIGHTGET)
                .setMethodCallHandler((call, result) -> {
                    if (call.method.equals("getCount")) {

                        System.out.println("连接状态" + isopen);
                        if(isopen){
                            mBLE_Service.disconnect();
                            isopen = false;
                            result.success(isopen);
                            return;
                        }
                        isopen = true;

                        ///==========================
                        Intent data = getIntent();
                        mdevice  = data.getParcelableExtra("Device");
                        UART_UUID = data.getStringExtra("DeviceUART");
                        TXO_UUID = data.getStringExtra("DeviceTXO");
                        RXI_UUID = data.getStringExtra("DeviceRXI");

//                        sevice = UUID.fromString(UART_UUID);
//                        txo = UUID.fromString(TXO_UUID);
//                        rxi = UUID.fromString(RXI_UUID);

                        sevice = UUID.fromString("0000FFE0-0000-1000-8000-00805F9B34FB");
                        txo = UUID.fromString("0000FFE1-0000-1000-8000-00805F9B34FB");
                        rxi = UUID.fromString("0000FFE1-0000-1000-8000-00805F9B34FB");



                        // 如果 mdevice 为 null 或者需要设置默认地址
                        if (mdevice == null || mdevice.getAddress() == null || mdevice.getAddress().isEmpty()) {
                            String defaultAddress = "88:25:83:F4:F7:4A";
                            mdevice = BluetoothAdapter.getDefaultAdapter().getRemoteDevice(defaultAddress);
                        }
                        
                        mBLE_Service.setUUID(sevice,txo,rxi);
                        mBLE_Service.disconnect();
                        mBLE_Service.connect(mdevice, this);

                        result.success(isopen);

                        /======================

                    } else {
                        result.notImplemented();
                    }
                });

        上面的UUID直接写死固定设备，包括设备的蓝牙地址我都是先直接写死

2、监听蓝牙模块的响应数据

SpBLE mBLE_Service;
mBLE_Service = new SpBLE(this,mHandler);

 封装好的蓝牙服务类文件

package com.example.yunhan_demo;

import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothServerSocket;
import android.bluetooth.BluetoothSocket;
import android.content.Context;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.UUID;

/**
 * This class does all the work for setting up and managing Bluetooth
 * connections with other devices. It has a thread that listens for
 * incoming connections, a thread for connecting with a device, and a
 * thread for performing data transmissions when connected.
 */
public class BluetoothChatService {
    // Debugging
    private static final String TAG = "BluetoothChatService";
    private static final boolean D = true;

    // Name for the SDP record when creating server socket
    private static final String NAME = "BluetoothCom";

    // Unique UUID for this application //Bluetooth serial board
    private static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
    //private static final UUID MY_UUID = UUID.fromString("fa87c0d0-afac-11de-8a39-0800200c9a66");
    //Hint: If you are connecting to a Bluetooth serial board then try using the well-known SPP UUID 00001101-0000-1000-8000-00805F9B34FB. 
    //However if you are connecting to an Android peer then please generate your own unique UUID.
    // Member fields
    private final BluetoothAdapter mAdapter;
    private final Handler mHandler;
    private AcceptThread mAcceptThread;
    private ConnectThread mConnectThread;
    private ConnectedThread mConnectedThread;
    private int mState;

    // Constants that indicate the current connection state
    public static final int STATE_NONE = 0;       // we're doing nothing
    public static final int STATE_LISTEN = 1;     // now listening for incoming connections
    public static final int STATE_CONNECTING = 2; // now initiating an outgoing connection
    public static final int STATE_CONNECTED = 3;  // now connected to a remote device

    /**
     * Constructor. Prepares a new BluetoothChat session.
     * @param context  The UI Activity Context
     * @param handler  A Handler to send messages back to the UI Activity
     */
    public BluetoothChatService(Context context, Handler handler) {
        mAdapter = BluetoothAdapter.getDefaultAdapter();
        mState = STATE_NONE;
        mHandler = handler;
    }

    /**
     * Set the current state of the chat connection
     * @param state  An integer defining the current connection state
     */
    private synchronized void setState(int state) {
        if (D) Log.d(TAG, "setState() " + mState + " -> " + 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();
    }

    /**
     * Return the current connection state. */
    public synchronized int getState() {
        return mState;
    }

    /**
     * Start the chat service. Specifically start AcceptThread to begin a
     * session in listening (server) mode. Called by the Activity onResume() */
    public synchronized void start() {
        if (D) Log.d(TAG, "start");

        // Cancel any thread attempting to make a connection
        if (mConnectThread != null) {mConnectThread.cancel(); mConnectThread = null;}

        // Cancel any thread currently running a connection
        if (mConnectedThread != null) {mConnectedThread.cancel(); mConnectedThread = null;}

        // Start the thread to listen on a BluetoothServerSocket
        if (mAcceptThread == null) {
            mAcceptThread = new AcceptThread();
            mAcceptThread.start();
        }
        setState(STATE_LISTEN);
    }

    /**
     * Start the ConnectThread to initiate a connection to a remote device.
     * @param device  The BluetoothDevice to connect
     */
    public synchronized void connect(BluetoothDevice device) {
        if (D) Log.d(TAG, "connect to: " + device);

        // Cancel any thread attempting to make a connection
        if (mState == STATE_CONNECTING) {
            if (mConnectThread != null) {mConnectThread.cancel(); mConnectThread = null;}
        }

        // Cancel any thread currently running a connection
        if (mConnectedThread != null) {mConnectedThread.cancel(); mConnectedThread = null;}

        // Start the thread to connect with the given device
        mConnectThread = new ConnectThread(device);
        mConnectThread.start();
        setState(STATE_CONNECTING);
    }

    /**
     * Start the ConnectedThread to begin managing a Bluetooth connection
     * @param socket  The BluetoothSocket on which the connection was made
     * @param device  The BluetoothDevice that has been connected
     */
    public synchronized void connected(BluetoothSocket socket, BluetoothDevice device) {
        if (D) Log.d(TAG, "connected");

        // Cancel the thread that completed the connection
        if (mConnectThread != null) {mConnectThread.cancel(); mConnectThread = null;}

        // Cancel any thread currently running a connection
        if (mConnectedThread != null) {mConnectedThread.cancel(); mConnectedThread = 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 = new ConnectedThread(socket);
        mConnectedThread.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(MainActivity.DEVICE_NAME, device.getName());
        msg.setData(bundle);
        mHandler.sendMessage(msg);

        setState(STATE_CONNECTED);
    }

    /**
     * Stop all threads
     */
    public synchronized void stop() {
        if (D) Log.d(TAG, "stop");
        if (mConnectThread != null) {mConnectThread.cancel(); mConnectThread = null;}
        if (mConnectedThread != null) {mConnectedThread.cancel(); mConnectedThread = null;}
        if (mAcceptThread != null) {mAcceptThread.cancel(); mAcceptThread = null;}
        setState(STATE_NONE);
    }

    /**
     * Write to the ConnectedThread in an unsynchronized manner
     * @param out The bytes to write
     * @see ConnectedThread#write(byte[])
     */
    public void write(byte[] out) {
        // Create temporary object
        ConnectedThread r;
        // Synchronize a copy of the ConnectedThread
        synchronized (this) {
            if (mState != STATE_CONNECTED) return;
            r = mConnectedThread;
        }
        // Perform the write unsynchronized
        r.write(out);
    }

    /**
     * Indicate that the connection attempt failed and notify the UI Activity.
     */
    private void connectionFailed() {
        setState(STATE_LISTEN);

        // Send a failure message back to the Activity
        Message msg = mHandler.obtainMessage(MainActivity.MESSAGE_TOAST);
        Bundle bundle = new Bundle();
        bundle.putString(MainActivity.TOAST, "连接失败");
        msg.setData(bundle);
        mHandler.sendMessage(msg);
    }

    /**
     * Indicate that the connection was lost and notify the UI Activity.
     */
    private void connectionLost() {
        setState(STATE_LISTEN);

        // Send a failure message back to the Activity
        Message msg = mHandler.obtainMessage(MainActivity.MESSAGE_TOAST);
        Bundle bundle = new Bundle();
        bundle.putString(MainActivity.TOAST, "蓝牙已断开连接");
        msg.setData(bundle);
        mHandler.sendMessage(msg);
    }

    /**
     * This thread runs while listening for incoming connections. It behaves
     * like a server-side client. It runs until a connection is accepted
     * (or until cancelled).
     */
    private class AcceptThread extends Thread {
        // The local server socket
        private final BluetoothServerSocket mmServerSocket;

        public AcceptThread() {
            BluetoothServerSocket tmp = null;

            // Create a new listening server socket
            try {
                tmp = mAdapter.listenUsingRfcommWithServiceRecord(NAME, MY_UUID);
            } catch (IOException e) {
                Log.e(TAG, "listen() failed", e);
            }
            mmServerSocket = tmp;
        }

        public void run() {
            if (D) Log.d(TAG, "BEGIN mAcceptThread" + this);
            setName("AcceptThread");
            BluetoothSocket socket = null;

            // Listen to the server socket if we're not connected
            while (mState != STATE_CONNECTED) {
                try {
                    // This is a blocking call and will only return on a
                    // successful connection or an exception
                    socket = mmServerSocket.accept();
                } catch (IOException e) {
                   // Log.e(TAG, "accept() failed", e);
                    break;
                }

                // If a connection was accepted
                if (socket != null) {
                    synchronized (BluetoothChatService.this) {
                        switch (mState) {
                        case STATE_LISTEN:
                        case STATE_CONNECTING:
                            // Situation normal. Start the connected thread.
                            connected(socket, socket.getRemoteDevice());
                            break;
                        case STATE_NONE:
                        case STATE_CONNECTED:
                            // Either not ready or already connected. Terminate new socket.
                            try {
                                socket.close();
                            } catch (IOException e) {
                                Log.e(TAG, "Could not close unwanted socket", e);
                            }
                            break;
                        }
                    }
                }
            }
            if (D) Log.i(TAG, "END mAcceptThread");
        }

        public void cancel() {
            if (D) Log.d(TAG, "cancel " + this);
            try {
                mmServerSocket.close();
            } catch (IOException e) {
                Log.e(TAG, "close() of server failed", e);
            }
        }
    }


    /**
     * This thread runs while attempting to make an outgoing connection
     * with a device. It runs straight through; the connection either
     * succeeds or fails.
     */
    private class ConnectThread extends Thread {
        private final BluetoothSocket mmSocket;
        private final BluetoothDevice mmDevice;

        public ConnectThread(BluetoothDevice device) {
            mmDevice = device;
            BluetoothSocket tmp = null;

            // Get a BluetoothSocket for a connection with the
            // given BluetoothDevice
            try {
                tmp = device.createRfcommSocketToServiceRecord(MY_UUID);
            } catch (IOException e) {
                Log.e(TAG, "create() failed", e);
            }
            mmSocket = tmp;
        }

        public void run() {
            Log.i(TAG, "BEGIN mConnectThread");
            setName("ConnectThread");

            // Always cancel discovery because it will slow down a connection
            mAdapter.cancelDiscovery();

            // Make a connection to the BluetoothSocket
            try {
                // This is a blocking call and will only return on a
                // successful connection or an exception
                mmSocket.connect();
            } catch (IOException e) {
                connectionFailed();
                // Close the socket
                try {
                    mmSocket.close();
                } catch (IOException e2) {
                    Log.e(TAG, "unable to close() socket during connection failure", e2);
                }
                // Start the service over to restart listening mode
                BluetoothChatService.this.start();
                return;
            }

            // Reset the ConnectThread because we're done
            synchronized (BluetoothChatService.this) {
                mConnectThread = null;
            }

            // Start the connected thread
            connected(mmSocket, mmDevice);
        }

        public void cancel() {
            try {
                mmSocket.close();
            } catch (IOException e) {
                Log.e(TAG, "close() of connect socket failed", e);
            }
        }
    }

    /**
     * This thread runs during a connection with a remote device.
     * It handles all incoming and outgoing transmissions.
     */
    private class ConnectedThread extends Thread {
        private final BluetoothSocket mmSocket;
        private final InputStream mmInStream;
        private final OutputStream mmOutStream;

        public ConnectedThread(BluetoothSocket socket) {
            Log.d(TAG, "create ConnectedThread");
            mmSocket = socket;
            InputStream tmpIn = null;
            OutputStream tmpOut = null;

            // Get the BluetoothSocket input and output streams
            try {
                tmpIn = socket.getInputStream();
                tmpOut = socket.getOutputStream();
            } catch (IOException e) {
                Log.e(TAG, "temp sockets not created", e);
            }

            mmInStream = tmpIn;
            mmOutStream = tmpOut;
        }

        public void run() {
            Log.i(TAG, "BEGIN mConnectedThread");
            byte[] buffer = new byte[1024];
            byte[] buffer2 = new byte[1024];
            int bytes;
            int i;
            // Keep listening to the InputStream while connected
            while (true) {
                try {
                    // Read from the InputStream
                    bytes = mmInStream.read(buffer);
                    if(bytes>0){
                    buffer2=buffer.clone();
                    for(i=0;i<buffer.length;i++)buffer[i]=0;
                    // Send the obtained bytes to the UI Activity
                    mHandler.obtainMessage(MainActivity.MESSAGE_READ, bytes, -1, buffer2)
                            .sendToTarget();
                    }
                } catch (IOException e) {
                    //Log.e(TAG, "disconnected", e);
                    connectionLost();
                    break;
                }
            }
        }

        /**
         * Write to the connected OutStream.
         * @param buffer  The bytes to write
         */
        public void write(byte[] buffer) {
            try {
                mmOutStream.write(buffer);

                // Share the sent message back to the UI Activity
                mHandler.obtainMessage(MainActivity.MESSAGE_WRITE, buffer.length, -1, buffer)
                        .sendToTarget();
            } catch (IOException e) {
                Log.e(TAG, "Exception during write", e);
            }
        }

        public void cancel() {
            try {
                mmSocket.close();
            } catch (IOException e) {
                Log.e(TAG, "close() of connect socket failed", e);
            }
        }
    }
}

3、处理获取蓝牙板块响应的数据 

    private final Handler mHandler = new Handler() {
               @Override
               public void handleMessage(Message msg) {
                   switch (msg.what) {
                    case 2:
                    byte[] readBuf = (byte[]) msg.obj;
                    String readMessage = null;
                    rxcount += msg.arg1;
                    rxs += msg.arg1;
                    Display_Data(readBuf,msg.arg1,false);    
 
            }

        }
    };

格式转换

void Display_Data(byte[] dat,int len,boolean isSend){
        String msg = "";
        boolean hex = false;
//        if(isSend){
//            hex =((CheckBox) (findViewById(R.id.txhex))).isChecked();
//        }else hex =((CheckBox) (findViewById(R.id.rxhex))).isChecked();

        if(hex) {
            try {
                msg = getHexString(dat, 0, len);
            } catch (UnsupportedEncodingException e) {
                throw new RuntimeException("Unsupported   encoding   type.");
            }
        }else {
            try{
                msg = new String(dat, 0, len,"GBK");
            }catch	(UnsupportedEncodingException   e){
                throw   new   RuntimeException("Unsupported   encoding   type.");
            }
        }
        show_data(msg);
        //if(isSend)Add_Sended(msg);
        //else Add_Readed(msg);
    }

public void show_data(String t){

        weighStr = t;

        System.out.println("获取接收称重数据" + weighStr);
}

最后在show_data里拿到的是打印数据

如图所示

完整代码我有时间会上传到仓库