通过蓝牙以编程方式连接两个Android设备

Question

I'm trying to get data from one of my devices to another, through bluetooth.

I previously tried to run the bluetoothChat sample code from the android website but have had no success.

I have now moved on to this bit of code that I have found and though it does compile on my devices they don't connect with one another.

Anyone see anything wrong with this code below? And if anyone might know of some good resources for bluetooth on the android I would be appreciative if they would share them with me!

package com.example.bluetooth;

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

import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

public class MainActivity extends Activity implements OnItemClickListener {

ArrayAdapter<String> listAdapter;
ListView listView;
BluetoothAdapter btAdapter;
Set<BluetoothDevice> devicesArray;
ArrayList<String> pairedDevices;
ArrayList<BluetoothDevice> devices;
public static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
protected static final int SUCCESS_CONNECT = 0;
protected static final int MESSAGE_READ = 1;
IntentFilter filter;
BroadcastReceiver receiver;
String tag = "debugging";
Handler mHandler = new Handler(){
    @Override
    public void handleMessage(Message msg) {
        // TODO Auto-generated method stub
        Log.i(tag, "in handler");
        super.handleMessage(msg);
        switch(msg.what){
        case SUCCESS_CONNECT:
            // DO something
            ConnectedThread connectedThread = new ConnectedThread((BluetoothSocket)msg.obj);
            Toast.makeText(getApplicationContext(), "CONNECT", Toast.LENGTH_SHORT).show();
            String s = "successfully connected";
            connectedThread.write(s.getBytes());
            Log.i(tag, "connected");
            break;
        case MESSAGE_READ:
            byte[] readBuf = (byte[])msg.obj;
            String string = new String(readBuf);
            Toast.makeText(getApplicationContext(), string, 0).show();
            break;
        }
    }
};
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    init();
    if(btAdapter==null){
        Toast.makeText(getApplicationContext(), "No bluetooth detected", 0).show();
        finish();
    }
    else{
        if(!btAdapter.isEnabled()){
            turnOnBT();
        }

        getPairedDevices();
        startDiscovery();//
    }


}

public void resumeDiscovery(View view){
    btAdapter.cancelDiscovery();
    btAdapter.startDiscovery();
}

private void startDiscovery() {
    // TODO Auto-generated method stub
    btAdapter.cancelDiscovery();
    btAdapter.startDiscovery();

}
private void turnOnBT() {
    // TODO Auto-generated method stub
    Intent intent =new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
    startActivityForResult(intent, 1);
}
private void getPairedDevices() {
    // TODO Auto-generated method stub
    devicesArray = btAdapter.getBondedDevices();
    if(devicesArray.size()>0){
        for(BluetoothDevice device:devicesArray){
            pairedDevices.add(device.getName());

        }
    }
}
private void init() {
    // TODO Auto-generated method stub
    listView=(ListView)findViewById(R.id.listView);
    listView.setOnItemClickListener(this);
    listAdapter= new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,0);
    listView.setAdapter(listAdapter);
    btAdapter = BluetoothAdapter.getDefaultAdapter();
    pairedDevices = new ArrayList<String>();
    filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
    devices = new ArrayList<BluetoothDevice>();
    receiver = new BroadcastReceiver(){
        @Override
        public void onReceive(Context context, Intent intent) {
            // TODO Auto-generated method stub
            String action = intent.getAction();

            if(BluetoothDevice.ACTION_FOUND.equals(action)){
                BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                devices.add(device);
                String s = "";
                for(int a = 0; a < pairedDevices.size(); a++){
                    if(device.getName().equals(pairedDevices.get(a))){
                        //append 
                        s = "(Paired)";
                        break;
                    }
                }

                listAdapter.add(device.getName()+" "+s+" "+"\n"+device.getAddress());
            }

            else if(BluetoothAdapter.ACTION_DISCOVERY_STARTED.equals(action)){
                // run some code
            }
            else if(BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)){
                // run some code



            }
            else if(BluetoothAdapter.ACTION_STATE_CHANGED.equals(action)){
                if(btAdapter.getState() == btAdapter.STATE_OFF){
                    turnOnBT();
                }
            }

        }
    };

    registerReceiver(receiver, filter);
     filter = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
    registerReceiver(receiver, filter);
     filter = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
    registerReceiver(receiver, filter);
     filter = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED);
    registerReceiver(receiver, filter);
}


@Override
protected void onPause() {
    // TODO Auto-generated method stub
    super.onPause();
    unregisterReceiver(receiver);
}

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        // TODO Auto-generated method stub
        super.onActivityResult(requestCode, resultCode, data);
        if(resultCode == RESULT_CANCELED){
            Toast.makeText(getApplicationContext(), "Bluetooth must be enabled to continue", Toast.LENGTH_SHORT).show();
            finish();
        }
    }
    public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
            long arg3) {
        // TODO Auto-generated method stub
        BluetoothDevice selectedDevice = devices.get(arg2);
        if(btAdapter.isDiscovering()){
            btAdapter.cancelDiscovery();
        }
        if(listAdapter.getItem(arg2).contains("Paired")){


            ConnectThread connect = new ConnectThread(selectedDevice);
            connect.start();
            Log.i(tag, "in click listener");
        }
        else{
            Toast.makeText(getApplicationContext(), "pairing", 0).show();
            //pair device
        }
    }

    private class ConnectThread extends Thread {

        private final BluetoothSocket mmSocket;
        private final BluetoothDevice mmDevice;

        public ConnectThread(BluetoothDevice device) {
            // Use a temporary object that is later assigned to mmSocket,
            // because mmSocket is final

            BluetoothSocket tmp = null;
            mmDevice = device;
            Log.i(tag, "construct");
            // Get a BluetoothSocket to connect with the given BluetoothDevice
            try {
                // MY_UUID is the app's UUID string, also used by the server code
                tmp = device.createRfcommSocketToServiceRecord(MY_UUID);
            } catch (IOException e) { 
                Log.i(tag, "get socket failed");

            }
            mmSocket = tmp;
        }



        public void run() {
            // Cancel discovery because it will slow down the connection
            btAdapter.cancelDiscovery();
            Log.i(tag, "connect - run");

            try {
                // Connect the device through the socket. This will block
                // until it succeeds or throws an exception
                mmSocket.connect();
                Log.i(tag, "connect - succeeded");
            } catch (IOException connectException) {    Log.i(tag, "connect failed");
                // Unable to connect; close the socket and get out
                try {
                    mmSocket.close();
                } catch (IOException closeException) { }
                return;
            }

            // Do work to manage the connection (in a separate thread)

            mHandler.obtainMessage(SUCCESS_CONNECT, mmSocket).sendToTarget();
        }



        /** Will cancel an in-progress connection, and close the socket */
        public void cancel() {
            try {
                mmSocket.close();
            } catch (IOException e) { }
        }
    }

    private class ConnectedThread extends Thread {
        private final BluetoothSocket mmSocket;
        private final InputStream mmInStream;
        private final OutputStream mmOutStream;

        public ConnectedThread(BluetoothSocket socket) {
            mmSocket = socket;
            InputStream tmpIn = null;
            OutputStream tmpOut = null;

            // Get the input and output streams, using temp objects because
            // member streams are final
            try {
                tmpIn = socket.getInputStream();
                tmpOut = socket.getOutputStream();
            } catch (IOException e) { }

            mmInStream = tmpIn;
            mmOutStream = tmpOut;
        }

        public void run() {
            byte[] buffer;  // buffer store for the stream
            int bytes; // bytes returned from read()

            // Keep listening to the InputStream until an exception occurs
            while (true) {
                try {
                    // Read from the InputStream
                    buffer = new byte[1024];
                    bytes = mmInStream.read(buffer);
                    // Send the obtained bytes to the UI activity
                    mHandler.obtainMessage(MESSAGE_READ, bytes, -1, buffer)
                            .sendToTarget();

                } catch (IOException e) {
                    break;
                }
            }
        }

        /* Call this from the main activity to send data to the remote device */
        public void write(byte[] bytes) {
            try {
                mmOutStream.write(bytes);
            } catch (IOException e) { }
        }

        /* Call this from the main activity to shutdown the connection */
        public void cancel() {
            try {
                mmSocket.close();
            } catch (IOException e) { }
        }
    }
}

Answer 1

The problem is in your init() method which registers the BroadcastReceiver with this activity in your onCreate() method and in onPause() you have unregistered the BroadcastReceiver.

Try to register it in your onResume() method so that you can receive the broadcast whenever you resume to this activity.