Android蓝牙详析 | 蓝牙的适配、权限、开启、搜索发现等处理

本系列笔记概述

• 蓝牙传输优势：功耗低，传输距离还可以；

• 蓝牙聊天室案例

• Android中蓝牙设备的使用
  • 蓝牙权限（本文的讲解内容之一）
  • 蓝牙功能开启（本文的讲解内容之一）
  • 搜索蓝牙设备（本文的讲解内容之一）
  • 与外设搭建RFCOMM通道（射频通道）
  • 蓝牙设备双向数据传输

蓝牙聊天室案例框架

• 蓝牙权限

  • 执行蓝牙通信需要权限BLUETOOTH，
    例如：请求连接、接收连接和传输数据等；

  • 如果需要启动设备 或 操作蓝牙设置，则需声明BLUETOOTH_ADMIN权限

• 设置蓝牙——获取BlueAdapter

  • 使用蓝牙需用到BlueAdapter。表示设备自身的蓝牙适配器；

  • 通过静态方法BlueAdapter.getDefaultAdapter()获得BlueAdapter；

  • 整个系统只有一个蓝牙适配器，application可使用此BlueAdapter对象与之交互；

  • 如果getDefaultAdapter()返回null，则表示该设备不支持蓝牙，
    例如：

BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
        if(mBluetoothAdapter == null){
            //Device does not support Bluetooth
        }

• 启用蓝牙

  • 调用isEnable()以检查当前是否已启用蓝牙；
    如果此方法返回false，则表示蓝牙处于停用状态；

  • 要请求启用蓝牙，将通过ACTION_REQUEST_ENABLE向系统设置
    发出启用蓝牙的请求（无需停止应用），
    例如：

...
    private static final int REQUEST_ENABLE_BT = 10;//其是需要自己定义的局部常量。
...

        if(mBluetoothAdapter.isEnabled()){
            Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
        }

---

demo（查看本机是否支持蓝牙，蓝牙是否开启，没开启则请求）：

• 新建一个项目，添加好如上述两个权限，编写MainActivity.java：

public class MainActivity extends AppCompatActivity {


    private static final String TAG = "BluetoothChat";
    private static final int REQUEST_ENABLE_BT = 10;//其是需要自己定义的局部常量。
    private BluetoothAdapter mBluetoothAdapter;

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

        mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
        if(mBluetoothAdapter == null){
            //Device does not support Bluetooth
            Log.e(TAG, "Device does not support Bluetooth");
        }else {
            Toast.makeText(this,"设备支持蓝牙！",Toast.LENGTH_SHORT).show();
        }
    }

    @Override
    protected void onStart() {
        super.onStart();

        if(!mBluetoothAdapter.isEnabled()){
            //向系统请求开启蓝牙
            Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);//结果返回回调到onActivityResult()
        }else {
            //已经开启了蓝牙
            Toast.makeText(this,"蓝牙已经开启",Toast.LENGTH_SHORT).show();
        }
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if(requestCode == REQUEST_ENABLE_BT){
            Toast.makeText(this,"蓝牙已经开启",Toast.LENGTH_SHORT).show();
        }
    }
}

---

• 查找设备——查找配对过的设备

  • getBondedDevices():返回已配对设备的一组BluetoothDevice

 Set pairedDevices = mBluetoothAdapter.getBondedDevices();
                //If threre are paired devices
                if (pairedDevices.size() > 0) {
                    //Loop through paired devices
                    for(BluetoothDevice device : pairedDevices){
                        //Add the name and address to an array adapter to show in a ListView
                        mArrayAdapter.add(device.getName() + "\n" + device.getAddress());
                    }
                }

• 查找设备——发现设备

  • 发现设备：startDiscovery()
    该进程为异步进程，
    该方法会立即返回一个布尔值，指示是否已成功启动发现操作；
  • 发现进程通常包含约12秒钟的查询扫描

1. 广播接收：

 //广播接收
    private BroadcastReceiver mBluetoothReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();//获取action
            Log.d(TAG, "ACTION：" + action);
            if(action.equals(BluetoothDevice.ACTION_FOUND)){
                //如果扫描时发现蓝牙设备，取到发现的设备
                BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);           
            }else if(action.equals(BluetoothAdapter.ACTION_DISCOVERY_FINISHED)){
                //如果扫描完毕                
            }
        }
    };

2. 广播过滤、注册、注销：

...
        //为广播接收器注册过滤器
        IntentFilter filter = new IntentFilter();
        filter.addAction(BluetoothDevice.ACTION_FOUND);
        filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
        registerReceiver(mBluetoothReceiver,filter);
...
    @Override
    protected void onDestroy() {
        super.onDestroy();
        unregisterReceiver(mBluetoothReceiver);
    }

---

demo（查找已配对蓝牙，log打印出来）：

续上，修改activity_main.xml：

接着修改MainActivity.java:
实例化、绑定：

...
//scan paired
    private Button mScanButton;
    private  Button mPairedDeviceButton;
...
        //scan paired
        mPairedDeviceButton = (Button)findViewById(R.id.bt_paired_device);
        mScanButton = (Button)findViewById(R.id.bt_scan);
...

添加onClick：

mPairedDeviceButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //paired 配对的
                Set pairedDevices = mBluetoothAdapter.getBondedDevices();
                //If threre are paired devices
//                if (pairedDevices.size() > 0) {
                    //Loop through paired devices
                    for(BluetoothDevice device : pairedDevices){
                        //You add the name and address to an array adapter to show in a ListView at this
                        Log.d(TAG, "Device name  " + device.getName());//打印匹配过的蓝牙设备的name
                        Log.d(TAG, "Device addr  " + device.getAddress());
                    }
//                }
            }
        });
        mScanButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(mBluetoothAdapter.isDiscovering()){//如果正在扫描，令之停止扫描，重新开始扫描
                    mBluetoothAdapter.cancelDiscovery();
                }
                mBluetoothAdapter.startDiscovery();//异步函数
            }
        });

运行之后点击“已配对设备”按钮，显示已配对蓝牙设备的信息：

此时java：

public class MainActivity extends AppCompatActivity {


    private static final String TAG = "BluetoothChat";
    private static final int REQUEST_ENABLE_BT = 10;//其是需要自己定义的局部常量。
    private BluetoothAdapter mBluetoothAdapter;

    //scan paired
    private Button mScanButton;
    private  Button mPairedDeviceButton;

    //广播接收

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

        //scan paired
        mPairedDeviceButton = (Button)findViewById(R.id.bt_paired_device);
        mScanButton = (Button)findViewById(R.id.bt_scan);
        mPairedDeviceButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //paired 配对的
                Set pairedDevices = mBluetoothAdapter.getBondedDevices();
                //If threre are paired devices
//                if (pairedDevices.size() > 0) {
                    //Loop through paired devices
                    for(BluetoothDevice device : pairedDevices){
                        //Add the name and address to an array adapter to show in a ListView
                        Log.d(TAG, "Device name  " + device.getName());//打印匹配过的蓝牙设备的name
                        Log.d(TAG, "Device addr  " + device.getAddress());
                    }
//                }
            }
        });
        mScanButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(mBluetoothAdapter.isDiscovering()){//如果正在扫描，令之停止扫描，重新开始扫描
                    mBluetoothAdapter.cancelDiscovery();
                }
                mBluetoothAdapter.startDiscovery();//异步函数
            }
        });

        mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
        if(mBluetoothAdapter == null){
            //Device does not support Bluetooth
            Log.e(TAG, "Device does not support Bluetooth");
        }else {
            Toast.makeText(this,"设备支持蓝牙！",Toast.LENGTH_SHORT).show();
        }


    }

    @Override
    protected void onStart() {
...
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
...
        }
    }
}

---

demo（续上，监测扫描发现设备时、扫描完毕时两个状态，做对应处理）：

• 点击“扫描附近蓝牙设备”按钮时，开始一轮新的扫描：

        mScanButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(mBluetoothAdapter.isDiscovering()){//如果正在扫描，令之停止扫描，重新开始扫描
                    mBluetoothAdapter.cancelDiscovery();
                }
                mBluetoothAdapter.startDiscovery();//异步函数
            }
        });

• 注册广播接收器，
  监测扫描发现设备时、扫描完毕时两个状态，
  然后做对应处理：

    //广播接收
    private BroadcastReceiver mBluetoothReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();//获取action
            Log.d(TAG, "ACTION：" + action);
            if(action.equals(BluetoothDevice.ACTION_FOUND)){
                //如果扫描时发现蓝牙设备，取到发现的设备
                BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                Log.d(TAG, "new Device name  " + device.getName());//打印匹配过的蓝牙设备的name
                Log.d(TAG, "new Device addr  " + device.getAddress());
            }else if(action.equals(BluetoothAdapter.ACTION_DISCOVERY_FINISHED)){
                //如果扫描完毕
                Toast.makeText(MainActivity.this,"Discovery done！",Toast.LENGTH_SHORT).show();
                Log.d(TAG, "Discovery done！");
            }
        }
    };

• 在onCreate()末尾注册intent过滤器：

        //为广播接收器注册过滤器
        IntentFilter filter = new IntentFilter();
        filter.addAction(BluetoothDevice.ACTION_FOUND);
        filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
        registerReceiver(mBluetoothReceiver,filter);

• 在onDestroy()中注销：

    @Override
    protected void onDestroy() {
        super.onDestroy();
        unregisterReceiver(mBluetoothReceiver);
    }

• 运行效果如图，没有发现新设备，在扫描完毕后打印出对应的Log：
  

• 此时java：

public class MainActivity extends AppCompatActivity {


    private static final String TAG = "BluetoothChat";
    private static final int REQUEST_ENABLE_BT = 10;//其是需要自己定义的局部常量。
    private BluetoothAdapter mBluetoothAdapter;

    //scan paired
    private Button mScanButton;
    private  Button mPairedDeviceButton;

    //广播接收
    private BroadcastReceiver mBluetoothReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();//获取action
            Log.d(TAG, "ACTION：" + action);
            if(action.equals(BluetoothDevice.ACTION_FOUND)){
                //如果扫描时发现蓝牙设备，取到发现的设备
                BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                Log.d(TAG, "new Device name  " + device.getName());//打印匹配过的蓝牙设备的name
                Log.d(TAG, "new Device addr  " + device.getAddress());
            }else if(action.equals(BluetoothAdapter.ACTION_DISCOVERY_FINISHED)){
                //如果扫描完毕
                Toast.makeText(MainActivity.this,"Discovery done！",Toast.LENGTH_SHORT).show();
                Log.d(TAG, "Discovery done！");
            }
        }
    };

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

        //scan paired
        mPairedDeviceButton = (Button)findViewById(R.id.bt_paired_device);
        mScanButton = (Button)findViewById(R.id.bt_scan);
        mPairedDeviceButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //paired 配对的
                Set pairedDevices = mBluetoothAdapter.getBondedDevices();
                //If threre are paired devices
//                if (pairedDevices.size() > 0) {
                    //Loop through paired devices
                    for(BluetoothDevice device : pairedDevices){
                        //Add the name and address to an array adapter to show in a ListView
                        Log.d(TAG, "Device name  " + device.getName());//打印匹配过的蓝牙设备的name
                        Log.d(TAG, "Device addr  " + device.getAddress());
                    }
//                }
            }
        });
        mScanButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(mBluetoothAdapter.isDiscovering()){//如果正在扫描，令之停止扫描，重新开始扫描
                    mBluetoothAdapter.cancelDiscovery();
                }
                mBluetoothAdapter.startDiscovery();//异步函数
            }
        });

        mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
        if(mBluetoothAdapter == null){
            //Device does not support Bluetooth
            Log.e(TAG, "Device does not support Bluetooth");
        }else {
            Toast.makeText(this,"设备支持蓝牙！",Toast.LENGTH_SHORT).show();
        }

        //为广播接收器注册过滤器
        IntentFilter filter = new IntentFilter();
        filter.addAction(BluetoothDevice.ACTION_FOUND);
        filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
        registerReceiver(mBluetoothReceiver,filter);
    }

    @Override
    protected void onStart() {
        super.onStart();

        if(!mBluetoothAdapter.isEnabled()){
            //向系统请求开启蓝牙
            Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);//结果返回回调到onActivityResult()
        }else {
            //已经开启了蓝牙
            Toast.makeText(this,"蓝牙已经开启",Toast.LENGTH_SHORT).show();
        }
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if(requestCode == REQUEST_ENABLE_BT){
            Toast.makeText(this,"蓝牙已经开启",Toast.LENGTH_SHORT).show();
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        unregisterReceiver(mBluetoothReceiver);
    }
}

参考自，慕课网。就业班