一、功能介绍

可实现两个手机之间的蓝牙通信，通过蓝牙接收和发送消息。

二、步骤及关键代码

1.新建工程MyBluetooth，在AndroidManifest.xml中添加权限申请

<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

2.修改布局文件activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <Button
        android:id="@+id/btn_openBT"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/open_bt"/>

    <Button
        android:layout_marginTop="10dp"
        android:id="@+id/btn_search"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/search"/>

    <TextView
        android:layout_marginTop="10dp"
        android:id="@+id/text_state"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/connect_state"/>

    <Button
        android:layout_marginTop="10dp"
        android:id="@+id/btn_send"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/send_msg"/>

    <TextView
        android:layout_marginTop="10dp"
        android:id="@+id/text_msg"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

    <ListView
        android:layout_marginTop="10dp"
        android:id="@+id/listView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</LinearLayout>

3.新建布局文件device_list.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal" android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:minHeight="58dp"
    android:padding="5dp">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:id="@+id/device_name"
        android:gravity="center_vertical"
        android:textColor="#000"/>

    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/device_info"
        android:gravity="center_vertical|right"
        android:textColor="#000"/>

</LinearLayout>

4.修改strings.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="app_name">MyBluetooth</string>
    <string name="open_bt">打开蓝牙</string>
    <string name="search">搜索设备</string>
    <string name="send_msg">发送消息</string>
    <string name="connect_error">连接失败</string>
    <string name="connect_success">连接成功</string>
    <string name="connecting">连接中</string>
    <string name="connect_state">连接状态</string>
    <string name="send_msgs">发送数据：</string>
    <string name="send_msg_error">发送数据失败：</string>
    <string name="get_msg">获取到数据：</string>

</resources>

5.编写MainActivity.java

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private BluetoothAdapter bTAdatper;
    private ListView listView;
    private Device adapter;

    private TextView text_state;
    private TextView text_msg;

    private final int BUFFER_SIZE = 1024;
    private static final String NAME = "BT_DEMO";
    private static final UUID BT_UUID = UUID.fromString("02001101-0001-1000-8080-00805F9BA9BA");

    private ConnectThread connectThread;
    private AcceptThread acceptThread;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
        bTAdatper = BluetoothAdapter.getDefaultAdapter();
        initReceiver();
        acceptThread = new AcceptThread();
        acceptThread.start();
    }

    private void initView() {
        findViewById(R.id.btn_openBT).setOnClickListener(this);
        findViewById(R.id.btn_search).setOnClickListener(this);
        findViewById(R.id.btn_send).setOnClickListener(this);
        text_state = (TextView) findViewById(R.id.text_state);
        text_msg = (TextView) findViewById(R.id.text_msg);

        listView = (ListView) findViewById(R.id.listView);
        adapter = new Device(getApplicationContext(), R.layout.device_list);
        listView.setAdapter(adapter);
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                if (bTAdatper.isDiscovering()) {
                    bTAdatper.cancelDiscovery();
                }
                BluetoothDevice device = (BluetoothDevice) adapter.getItem(position);
                //连接设备
                connectDevice(device);
            }
        });
    }

    private void initReceiver() {
        //注册广播
        IntentFilter filter = new IntentFilter();
        filter.addAction(BluetoothDevice.ACTION_FOUND);
        filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
        filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
        registerReceiver(mReceiver, filter);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.btn_openBT:
                openBlueTooth();
                break;
            case R.id.btn_search:
                searchDevices();
                break;
            case R.id.btn_send:
                if (connectThread != null) {
                    connectThread.sendMsg("这是蓝牙发送过来的消息");
                }
                break;
        }
    }


    /**
     * 开启蓝牙
     */
    private void openBlueTooth() {
        if (bTAdatper == null) {
            Toast.makeText(this, "当前设备不支持蓝牙功能", Toast.LENGTH_SHORT).show();
        }
        if (!bTAdatper.isEnabled()) {
           /* Intent i = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivity(i);*/
            bTAdatper.enable();
        }
        //开启被其它蓝牙设备发现的功能
        if (bTAdatper.getScanMode() != BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE) {
            Intent i = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
            //设置为一直开启
            i.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 0);
            startActivity(i);
        }
    }

    /**
     * 搜索蓝牙设备
     */
    private void searchDevices() {
        if (bTAdatper.isDiscovering()) {
            bTAdatper.cancelDiscovery();
        }
        getBoundedDevices();
        bTAdatper.startDiscovery();
    }

    /**
     * 获取已经配对过的设备
     */
    private void getBoundedDevices() {
        //获取已经配对过的设备
        Set<BluetoothDevice> pairedDevices = bTAdatper.getBondedDevices();
        //将其添加到设备列表中
        if (pairedDevices.size() > 0) {
            for (BluetoothDevice device : pairedDevices) {
                adapter.add(device);
            }
        }
    }

    /**
     * 连接蓝牙设备
     */
    private void connectDevice(BluetoothDevice device) {

        text_state.setText(getResources().getString(R.string.connecting));

        try {
            //创建Socket
            BluetoothSocket socket = device.createRfcommSocketToServiceRecord(BT_UUID);
            //启动连接线程
            connectThread = new ConnectThread(socket, true);
            connectThread.start();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        //取消搜索
        if (bTAdatper != null && bTAdatper.isDiscovering()) {
            bTAdatper.cancelDiscovery();
        }
        //注销BroadcastReceiver，防止资源泄露
        unregisterReceiver(mReceiver);
    }

    private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            if (BluetoothDevice.ACTION_FOUND.equals(action)) {
                BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                //避免重复添加已经绑定过的设备
                if (device.getBondState() != BluetoothDevice.BOND_BONDED) {
                    adapter.add(device);
                    adapter.notifyDataSetChanged();
                }
            } else if (BluetoothAdapter.ACTION_DISCOVERY_STARTED.equals(action)) {
                Toast.makeText(MainActivity.this, "开始搜索", Toast.LENGTH_SHORT).show();
            } else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
                Toast.makeText(MainActivity.this, "搜索完毕", Toast.LENGTH_SHORT).show();
            }
        }
    };

    /**
     * 连接线程
     */
    private class ConnectThread extends Thread {

        private BluetoothSocket socket;
        private boolean activeConnect;
        InputStream inputStream;
        OutputStream outputStream;

        private ConnectThread(BluetoothSocket socket, boolean connect) {
            this.socket = socket;
            this.activeConnect = connect;
        }

        @Override
        public void run() {
            try {
                //如果是自动连接 则调用连接方法
                if (activeConnect) {
                    socket.connect();
                }
                text_state.post(new Runnable() {
                    @Override
                    public void run() {
                        text_state.setText(getResources().getString(R.string.connect_success));
                    }
                });
                inputStream = socket.getInputStream();
                outputStream = socket.getOutputStream();

                byte[] buffer = new byte[BUFFER_SIZE];
                int bytes;
                while (true) {
                    //读取数据
                    bytes = inputStream.read(buffer);
                    if (bytes > 0) {
                        final byte[] data = new byte[bytes];
                        System.arraycopy(buffer, 0, data, 0, bytes);
                        text_msg.post(new Runnable() {
                            @Override
                            public void run() {
                                text_msg.setText(getResources().getString(R.string.get_msg)+new String(data));
                            }
                        });
                    }
                }
            } catch (IOException e) {
                e.printStackTrace();
                text_state.post(new Runnable() {
                    @Override
                    public void run() {
                        text_state.setText(getResources().getString(R.string.connect_error));
                    }
                });
            }
        }

        /**
         * 发送数据
         *
         * @param msg
         */
        public void sendMsg(final String msg) {

            byte[] bytes = msg.getBytes();
            if (outputStream != null) {
                try {
                    //发送数据
                    outputStream.write(bytes);
                    text_msg.post(new Runnable() {
                        @Override
                        public void run() {
                            text_msg.setText(getResources().getString(R.string.send_msgs)+msg);
                        }
                    });
                } catch (IOException e) {
                    e.printStackTrace();
                    text_msg.post(new Runnable() {
                        @Override
                        public void run() {
                            text_msg.setText(getResources().getString(R.string.send_msg_error)+msg);
                        }
                    });
                }
            }
        }
    }

    /**
     * 监听线程
     */
    private class AcceptThread extends Thread {

        private BluetoothServerSocket serverSocket;
        private BluetoothSocket socket;

        @Override
        public void run() {
            try {
                serverSocket = bTAdatper.listenUsingRfcommWithServiceRecord(
                        NAME, BT_UUID);
                while (true) {
                    //线程阻塞，等待别的设备连接
                    socket = serverSocket.accept();
                    text_state.post(new Runnable() {
                        @Override
                        public void run() {
                            text_state.setText(getResources().getString(R.string.connecting));
                        }
                    });
                    connectThread = new ConnectThread(socket, false);
                    connectThread.start();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

6.新建Device.java

package com.example.mybluetooth;

import android.bluetooth.BluetoothDevice;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;

public class BlueToothDeviceAdapter extends ArrayAdapter<BluetoothDevice> {

    private final LayoutInflater mInflater;
    private int mResource;

    public BlueToothDeviceAdapter(Context context, int resource) {
        super(context, resource);
        mInflater = LayoutInflater.from(context);
        mResource = resource;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        if (convertView == null) {
            convertView = mInflater.inflate(mResource, parent, false);
        }

        TextView name = (TextView) convertView.findViewById(R.id.device_name);
        TextView info = (TextView) convertView.findViewById(R.id.device_info);
        BluetoothDevice device = getItem(position);
        name.setText(device.getName());
        info.setText(device.getAddress());

        return convertView;
    }
}