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注意事项
- 低功耗蓝牙(BLE)Android 4.3（API 18）以上才支持
- 使用蓝牙需要权限
<uses-permission android:name="android.permission.BLUETOOTH" /> <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" /> - Android 5.0(API 21) 扫描蓝牙需要定位权限，否则扫描不到设备,实际使用时候发现 5.0不需要也可以扫描，Android 6.0(API 23)以上必须（不知道什么原因，测试机器：MI 2，知道原因的可告知）
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/> 或 <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> - 低功耗蓝牙要声明特征，或者代码判断
// 如果为true表示只能在支持低功耗蓝牙的设备上使用，如果不支持的设备也可以使用，采用代码判断 <uses-feature android:name="android.hardware.bluetooth_le" android:required="true"/> // 代码判断 if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) { Toast.makeText(this, R.string.ble_not_supported, Toast.LENGTH_SHORT).show(); finish(); } - 经典蓝牙连接成功后获取一个socket连接得到输入输出流进行通信，低功耗通过特征（具体实现不知道是什么）
- Android 5.0（API 21）之前不能当成外设(蓝牙耳机、音响等)来使用，只能作为中心即主机
低功耗蓝牙
现在蓝牙开发基本上都是低功耗蓝牙，比如心率设备、耳机设备、手环，所以我们先从重要的开始，讲讲低功耗蓝牙的使用，后面在完善经典蓝牙。
声明权限
创建项目在AndroidManifest.xml中声明权限：
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.lowett.android"> // 定位权限第二个包含第一个，所以这里就声明了一个，两个都声明也可以 <!-- <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/> --> <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/> <uses-permission android:name="android.permission.BLUETOOTH"/> <uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/> // 是否必须支持低功耗蓝牙，此处不必须 <uses-feature android:name="android.hardware.bluetooth_le" android:required="false"/> // 是有gps硬件，这个现在的智能手机没有不支持的吧 <uses-feature android:name="android.hardware.location.gps"/> </manifest>
如果manifest中声明的蓝牙特性为false，那么在代码中监测是否支持BLE特性，
// 使用此检查确定BLE是否支持在设备上，然后你可以有选择性禁用BLE相关的功能
if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
Toast.makeText(this, R.string.ble_not_supported, Toast.LENGTH_SHORT).show();
finish();
}
BluetoothAdapter
获取BluetoothManager得到蓝牙适配器BluetoothAdapter，注意这两个类都是系统级别，只有一个，代表了你手机上的蓝牙模块
final BluetoothManager bluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
BluetoothAdapter bluetoothAdapter = bluetoothManager.getAdapter();
如果获取到的Adapter为空说明不支持蓝牙，或者没有蓝牙模块
开启蓝牙
前面获取到了BluetoothAdapter，可以通过调用isEnabled()函数去检测是否开启了蓝牙，false表示没有开启，如果没有开启需要去启用，
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Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
activity.startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
代码执行完后，会有弹框提示用户是否启用，我们需要在onActivityResult()中判断返回
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); if (requestCode == BluetoothLeManager.REQUEST_ENABLE_BT) { if (resultCode == Activity.RESULT_OK) { // something, 去扫描设备 startScan(); } else { new AlertDialog.Builder(this) .setMessage("请开启蓝牙，连接设备") .setPositiveButton(R.string.confirm, new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { dialog.dismiss(); // something } }) .create() .show(); } } }
扫描设备
低功耗蓝牙和经典蓝牙的扫描方式不同，如果熟悉经典蓝牙，那就要可能掉进坑了起不来了，哈哈。蓝牙扫描耗电比较严重，所以此处一定要记得在合适的实际停止扫描，比如定时停止、扫描到目标设备就停止（奇怪的是API为何不提供扫描时长的接口呢？）扫描时调用Adapter的startLeScan()方法,然而这个被标记为过时，API>=21被另一个取代。然后通过回掉得到扫描结果（经典蓝牙是广播）
public void startScan() {
// 初始化一个handler initHandler(); if (!mScanning) { if (scanRunnable == null) { scanRunnable = new Runnable() { @Override public void run() { stopScan(); } }; } // SCAN_PERIOD = 3 * 10 * 1000, 30s后停止扫面 mHandler.postDelayed(scanRunnable, SCAN_PERIOD); // 新API // if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) { // mBluetoothAdapter.getBluetoothLeScanner().startScan(this); // }else { // this 实现了BluetoothAdapter.LeScanCallback，即扫描结果回掉 mBluetoothAdapter.startLeScan(this); // } mScanning = true; Log.i(TAG, "开始扫描，蓝牙设备"); } }
回调函数
@Override
public void onLeScan(BluetoothDevice device, int rssi, byte[] scanRecord) { // 得到扫描结果 Log.i(TAG, "扫描到的设备, name=" + device.getName() + ",address=" + device.toString()); }
注意：device：代表外设即目标设备 rssi：设一个强度值，但是时负值，利用这个值通过公式可以算出离你的距离
scanRecord：广播数据，附加的数据，没用到
停止扫描
扫描完成务必停止，因为扫描不仅耗电，还影响连接速度，所以当要连接的时候，先停止扫描时必须的
public void stopScan() {
initHandler();
Log.i(TAG, "停止扫描，蓝牙设备"); if (mScanning) { mScanning = false; // 开始扫描的接口,要一样的不然停止不了 mBluetoothAdapter.stopLeScan(this); } if (scanRunnable != null) { mHandler.removeCallbacks(scanRunnable); scanRunnable = null; } }
连接设备
通常连接设备速度还是很快的，连接理论上来说也是无状态的，所以也需要一个定式任务来，保证超时停止。
public boolean connect(Context context, String address) {
if (mConnectionState == STATE_CONNECTED) { return false; } if (mBluetoothAdapter == null || TextUtils.isEmpty(address)) { return false; } initHandler(); if (connectRunnable == null) { connectRunnable = new Runnable() { @Override public void run() { mConnectionState = STATE_DISCONNECTING; disconnect(); } }; } // 30s没反应停止连接 mHandler.postDelayed(connectRunnable, 30 * 1000); stopScan(); // 获取到远程设备， final BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(address); if (device == null) { return false; } // 开始连接，第二个参数表示是否需要自动连接，true设备靠近自动连接，第三个表示连接回调 mBluetoothGatt = device.connectGatt(context, false, mGattCallback); mBluetoothDeviceAddress = address; mConnectionState = STATE_CONNECTING; return true; }
监听连接回调
private final BluetoothGattCallback mGattCallback = new BluetoothGattCallback() {
// 连接状态变化
@Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) { if (newState == BluetoothProfile.STATE_CONNECTED) { // 连接上 mConnectionState = STATE_CONNECTED; boolean success = mBluetoothGatt.discoverServices(); // 去发现服务 Log.i(TAG, "Attempting to start service discovery:" + success); } else if (newState == BluetoothProfile.STATE_DISCONNECTED) { // 连接断开 mConnectionState = STATE_DISCONNECTED; } } // 发现服务 @Override public void onServicesDiscovered(BluetoothGatt gatt, int status) { if (status == BluetoothGatt.GATT_SUCCESS) { Log.i(TAG,"发现服务"); // 解析服务 discoverService(); } } // 特征读取变化 @Override public void onCharacteristicRead(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) { if (status == BluetoothGatt.GATT_SUCCESS) { } } // 收到数据 @Override public void onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic) { mConnectionState = STATE_CONNECTED; } };
断开连接
public void disconnect() {
if (mBluetoothAdapter == null || mBluetoothGatt == null) { mConnectionState = STATE_DISCONNECTED; return; } // 连接成功的GATT mBluetoothGatt.disconnect(); mBluetoothGatt.close(); }
多设备连接
蓝牙适配器没有听过连接多个设备的接口，需要我们自己实现，即获取到目标设备的address后调用连接方法，自己维护多个BluetoothGatt即可(代码稍后放出)。
完整代码示例
正在做心率相关的蓝牙设备，此处代码发出来。
代码还在完善中，仅供参考，稳定代码将会发在Github中
package com.lowett.android.ble;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothGatt;
import android.bluetooth.BluetoothGattCallback; import android.bluetooth.BluetoothGattCharacteristic; import android.bluetooth.BluetoothGattDescriptor; import android.bluetooth.BluetoothGattService; import android.bluetooth.BluetoothManager; import android.bluetooth.BluetoothProfile; import android.content.Context; import android.content.Intent; import android.content.pm.PackageManager; import android.os.Handler; import android.os.Looper; import android.support.annotation.IntDef; import android.text.TextUtils; import com.fit.android.utils.Logger; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.util.List; import java.util.Locale; import java.util.UUID; /** * Email: [email protected] */ public class BluetoothLeManager implements BluetoothAdapter.LeScanCallback { public static final int REQUEST_ENABLE_BT = 1; private static final int SCAN_PERIOD = 3 * 10 * 1000; static final int STATE_DISCONNECTED = 1; public static final int STATE_CONNECTING = 2; public static final int STATE_DISCONNECTING = 3; public static final int STATE_CONNECTED = 4; public static final int STATE_DISCOVER_SERVICES = 5; @IntDef(value = {STATE_DISCONNECTED, STATE_CONNECTING, STATE_CONNECTED, STATE_DISCONNECTING, STATE_DISCOVER_SERVICES}) @Retention(RetentionPolicy.SOURCE) public @interface State { } public final static UUID UUID_HEART_RATE_MEASUREMENT = UUID.fromString(SampleGattAttributes.HEART_RATE_MEASUREMENT); private static BluetoothLeManager ourInstance = new BluetoothLeManager(); // private Context mContext; private boolean is_inited = false; private android.bluetooth.BluetoothManager mBluetoothManager; private BluetoothAdapter mBluetoothAdapter; private String mBluetoothDeviceAddress; private int mConnectionState; private BluetoothGatt mBluetoothGatt; private boolean mScanning; private Runnable scanRunnable; private Handler mHandler; private Runnable connectRunnable; private OnDataReceivedListener mOnDataReceivedListener; // 记得清掉监听 泄漏 private OnLeScanListener mOnLeScanListener; private OnConnectionStateChangeListener mOnConnectionStateChangeListener; private int retryCount; public static BluetoothLeManager getInstance() { return ourInstance; } private BluetoothLeManager() { } public void setOnDataReceivedListener(OnDataReceivedListener onDataReceivedListener) { mOnDataReceivedListener = onDataReceivedListener; } public interface OnConnectionStateChangeListener { void onConnectionStateChange(BluetoothGatt gatt, int status, int newState); void onConnectTimeout(); } public void setOnConnectionStateChangeListener(OnConnectionStateChangeListener onConnectionStateChangeListener) { mOnConnectionStateChangeListener = onConnectionStateChangeListener; } public interface OnLeScanListener { void onLeScan(BluetoothDevice device); } public interface OnDataReceivedListener { void onDataReceived(int heart); } private void init() { if (!is_inited) { is_inited = true; } } private boolean initialize(Context context) { init(); if (!is_inited) { throw new RuntimeException("请先调用init"); } if (mBluetoothAdapter != null) { return true; } // For API level 18 and above, get a reference to BluetoothAdapter through // BluetoothLeManager. if (mBluetoothManager == null) { mBluetoothManager = (BluetoothManager) context.getSystemService(Context.BLUETOOTH_SERVICE); if (mBluetoothManager == null) { return false; } } mBluetoothAdapter = mBluetoothManager.getAdapter(); return mBluetoothAdapter != null; } public boolean isSupportBluetoothLe(Activity activity) { return activity.getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE); } public boolean isSupportBluetooth(Context context) { return initialize(context); } public void enableBluetooth(Activity activity) { if (!initialize(activity)) { return; } if (!mBluetoothAdapter.isEnabled()) { Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE); activity.startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT); } } public boolean isEnabled(Context context) { return initialize(context) && mBluetoothAdapter.isEnabled(); } private void initHandler() { if (mHandler == null) { mHandler = new Handler(Looper.getMainLooper()); } } public void startScan(OnLeScanListener onLeScanListener) { initHandler(); if (!mScanning) { if (scanRunnable == null) { scanRunnable = new Runnable() { @Override public void run() { stopScan(); } }; } mHandler.postDelayed(scanRunnable, SCAN_PERIOD); // if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) { // mBluetoothAdapter.getBluetoothLeScanner().startScan(this); // }else { mBluetoothAdapter.startLeScan(this); // } mScanning = true; this.mOnLeScanListener = onLeScanListener; Logger.i("开始扫描，蓝牙设备"); } } @Override public void onLeScan