Android提高之Android手机与BLE终端通信

最近穿戴设备发展得很火，把相关技术也带旺了，其中一项是ble（bluetooth low energy）。ble是蓝牙4.0的核心profile，主打功能是快速搜索，快速连接，超低功耗保持连接和传输数据，弱点是数据传输速率低，由于ble的低功耗特点，因此普遍用于穿戴设备。android 4.3才开始支持ble api，所以请各位客官把本文代码运行在蓝牙4.0和android 4.3及其以上的系统，另外本文所用的ble终端是一个蓝牙4.0的串口蓝牙模块。

注：笔者的i9100刷了4.4系统后，竟然也能跟ble蓝牙模块通信。

ble分为三部分service、characteristic、descriptor，这三部分都由uuid作为唯一标示符。一个蓝牙4.0的终端可以包含多个service，一个service可以包含多个characteristic，一个characteristic包含一个value和多个descriptor，一个descriptor包含一个value。一般来说，characteristic是手机与ble终端交换数据的关键，characteristic有较多的跟权限相关的字段，例如permission和property，而其中最常用的是property，本文所用的ble蓝牙模块竟然没有标准的characteristic的permission。characteristic的property可以通过位运算符组合来设置读写属性，例如read|write、read|write_no_response|notify，因此读取property后要分解成所用的组合（本文代码已含此分解方法）。

本文代码改自android 4.3 sample的bluetoothlegatt，把冗余代码去掉，获取的ble设备信息都通过log，还有一些必要的读写蓝牙方法，应该算是简化到大家一看就可以懂了。本文完整代码可以点击此处本站下载。

接下来贴出本文运行的结果，首先是连接ble设备后，枚举出设备所有service、characteristic、descriptor，并且手机会往characteristic uuid=0000ffe1-0000-1000-8000-00805f9b34fb写入“send data->”字符串，ble终端收到数据通过串口传到pc串口助手：
04-21 18:28:25.465: e/devicescanactivity(12254): -->service type:primary
04-21 18:28:25.465: e/devicescanactivity(12254): -->includedservices size:0
04-21 18:28:25.465: e/devicescanactivity(12254): -->service uuid:00001800-0000-1000-8000-00805f9b34fb
04-21 18:28:25.465: e/devicescanactivity(12254): ---->char uuid:00002a00-0000-1000-8000-00805f9b34fb
04-21 18:28:25.465: e/devicescanactivity(12254): ---->char permission:unknow
04-21 18:28:25.465: e/devicescanactivity(12254): ---->char property:read
04-21 18:28:25.465: e/devicescanactivity(12254): ---->char uuid:00002a01-0000-1000-8000-00805f9b34fb
04-21 18:28:25.470: e/devicescanactivity(12254): ---->char permission:unknow
04-21 18:28:25.470: e/devicescanactivity(12254): ---->char property:read
04-21 18:28:25.470: e/devicescanactivity(12254): ---->char uuid:00002a02-0000-1000-8000-00805f9b34fb
04-21 18:28:25.470: e/devicescanactivity(12254): ---->char permission:unknow
04-21 18:28:25.470: e/devicescanactivity(12254): ---->char property:read|write|
04-21 18:28:25.470: e/devicescanactivity(12254): ---->char uuid:00002a03-0000-1000-8000-00805f9b34fb
04-21 18:28:25.470: e/devicescanactivity(12254): ---->char permission:unknow
04-21 18:28:25.475: e/devicescanactivity(12254): ---->char property:read|write|
04-21 18:28:25.475: e/devicescanactivity(12254): ---->char uuid:00002a04-0000-1000-8000-00805f9b34fb
04-21 18:28:25.475: e/devicescanactivity(12254): ---->char permission:unknow
04-21 18:28:25.475: e/devicescanactivity(12254): ---->char property:read
04-21 18:28:25.475: e/devicescanactivity(12254): -->service type:primary
04-21 18:28:25.475: e/devicescanactivity(12254): -->includedservices size:0
04-21 18:28:25.475: e/devicescanactivity(12254): -->service uuid:00001801-0000-1000-8000-00805f9b34fb
04-21 18:28:25.480: e/devicescanactivity(12254): ---->char uuid:00002a05-0000-1000-8000-00805f9b34fb
04-21 18:28:25.480: e/devicescanactivity(12254): ---->char permission:unknow
04-21 18:28:25.480: e/devicescanactivity(12254): ---->char property:indicate
04-21 18:28:25.480: e/devicescanactivity(12254): -------->desc uuid:00002902-0000-1000-8000-00805f9b34fb
04-21 18:28:25.480: e/devicescanactivity(12254): -------->desc permission:unknow
04-21 18:28:25.480: e/devicescanactivity(12254): -->service type:primary
04-21 18:28:25.480: e/devicescanactivity(12254): -->includedservices size:0
04-21 18:28:25.480: e/devicescanactivity(12254): -->service uuid:0000ffe0-0000-1000-8000-00805f9b34fb
04-21 18:28:25.480: e/devicescanactivity(12254): ---->char uuid:0000ffe1-0000-1000-8000-00805f9b34fb
04-21 18:28:25.480: e/devicescanactivity(12254): ---->char permission:unknow
04-21 18:28:25.480: e/devicescanactivity(12254): ---->char property:read|write_no_response|notify|
04-21 18:28:25.490: e/devicescanactivity(12254): -------->desc uuid:00002902-0000-1000-8000-00805f9b34fb
04-21 18:28:25.490: e/devicescanactivity(12254): -------->desc permission:unknow
04-21 18:28:25.490: e/devicescanactivity(12254): -------->desc uuid:00002901-0000-1000-8000-00805f9b34fb
04-21 18:28:25.490: e/devicescanactivity(12254): -------->desc permission:unknow
04-21 18:28:26.025: e/devicescanactivity(12254): oncharread ble device read 0000ffe1-0000-1000-8000-00805f9b34fb -> 00
这里红字是由bluetoothgattcallback的oncharacteristicread()回调而打出log

以下log是pc上的串口工具通过ble模块发送过来，由bluetoothgattcallback的 oncharacteristicchanged（）打出log
04-21 18:30:18.260: e/devicescanactivity(12254): oncharwrite ble device write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone
04-21 18:30:18.745: e/devicescanactivity(12254): oncharwrite ble device write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone
04-21 18:30:19.085: e/devicescanactivity(12254): oncharwrite ble device write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone
04-21 18:30:19.350: e/devicescanactivity(12254): oncharwrite ble device write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone
04-21 18:30:19.605: e/devicescanactivity(12254): oncharwrite ble device write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone
04-21 18:30:19.835: e/devicescanactivity(12254): oncharwrite ble device write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone
04-21 18:30:20.055: e/devicescanactivity(12254): oncharwrite ble device write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone
04-21 18:30:20.320: e/devicescanactivity(12254): oncharwrite ble device write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone
04-21 18:30:20.510: e/devicescanactivity(12254): oncharwrite ble device write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone
04-21 18:30:20.735: e/devicescanactivity(12254): oncharwrite ble device write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone
04-21 18:30:21.000: e/devicescanactivity(12254): oncharwrite ble device write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone

接下来贴出本文核心代码：

public class devicescanactivity extends listactivity {
 private final static string tag = devicescanactivity.class.getsimplename();
 private final static string uuid_key_data = "0000ffe1-0000-1000-8000-00805f9b34fb";

  private ledevicelistadapter mledevicelistadapter;
  /**搜索ble终端*/
  private bluetoothadapter mbluetoothadapter;
  /**读写ble终端*/
  private bluetoothleclass mble;
  private boolean mscanning;
  private handler mhandler;

  // stops scanning after 10 seconds.
  private static final long scan_period = 10000;

  @override
  public void oncreate(bundle savedinstancestate) {
    super.oncreate(savedinstancestate);
    getactionbar().settitle(r.string.title_devices);
    mhandler = new handler();
    // use this check to determine whether ble is supported on the device. then you can
    // selectively disable ble-related features.
    if (!getpackagemanager().hassystemfeature(packagemanager.feature_bluetooth_le)) {
      toast.maketext(this, r.string.ble_not_supported, toast.length_short).show();
      finish();
    }
    // initializes a bluetooth adapter. for api level 18 and above, get a reference to
    // bluetoothadapter through bluetoothmanager.
    final bluetoothmanager bluetoothmanager =
        (bluetoothmanager) getsystemservice(context.bluetooth_service);
    mbluetoothadapter = bluetoothmanager.getadapter();
    // checks if bluetooth is supported on the device.
    if (mbluetoothadapter == null) {
      toast.maketext(this, r.string.error_bluetooth_not_supported, toast.length_short).show();
      finish();
      return;
    }
    //开启蓝牙
    mbluetoothadapter.enable();
    mble = new bluetoothleclass(this);
    if (!mble.initialize()) {
      log.e(tag, "unable to initialize bluetooth");
      finish();
    }
    //发现ble终端的service时回调
    mble.setonservicediscoverlistener(monservicediscover);
    //收到ble终端数据交互的事件
    mble.setondataavailablelistener(mondataavailable);
  }
  @override
  protected void onresume() {
    super.onresume();

    // initializes list view adapter.
    mledevicelistadapter = new ledevicelistadapter(this);
    setlistadapter(mledevicelistadapter);
    scanledevice(true);
  }
  @override
  protected void onpause() {
    super.onpause();
    scanledevice(false);
    mledevicelistadapter.clear();
    mble.disconnect();
  }
  @override
  protected void onstop() {
    super.onstop();
    mble.close();
  }
  @override
  protected void onlistitemclick(listview l, view v, int position, long id) {
    final bluetoothdevice device = mledevicelistadapter.getdevice(position);
    if (device == null) return;
    if (mscanning) {
      mbluetoothadapter.stoplescan(mlescancallback);
      mscanning = false;
    }
    mble.connect(device.getaddress());
  }
  private void scanledevice(final boolean enable) {
    if (enable) {
      // stops scanning after a pre-defined scan period.
      mhandler.postdelayed(new runnable() {
        @override
        public void run() {
          mscanning = false;
          mbluetoothadapter.stoplescan(mlescancallback);
          invalidateoptionsmenu();
        }
      }, scan_period);
      mscanning = true;
      mbluetoothadapter.startlescan(mlescancallback);
    } else {
      mscanning = false;
      mbluetoothadapter.stoplescan(mlescancallback);
    }
    invalidateoptionsmenu();
  }
  /**
   * 搜索到ble终端服务的事件
   */
  private bluetoothleclass.onservicediscoverlistener monservicediscover = new onservicediscoverlistener(){

 @override
 public void onservicediscover(bluetoothgatt gatt) {
  displaygattservices(mble.getsupportedgattservices());
 }
  };
  /**
   * 收到ble终端数据交互的事件
   */
  private bluetoothleclass.ondataavailablelistener mondataavailable = new ondataavailablelistener(){
   /**
   * ble终端数据被读的事件
   */
 @override
 public void oncharacteristicread(bluetoothgatt gatt,
  bluetoothgattcharacteristic characteristic, int status) {
  if (status == bluetoothgatt.gatt_success) 
  log.e(tag,"oncharread "+gatt.getdevice().getname()
   +" read "
   +characteristic.getuuid().tostring()
   +" -> "
   +utils.bytestohexstring(characteristic.getvalue()));
 }
   /**
   * 收到ble终端写入数据回调
   */
 @override
 public void oncharacteristicwrite(bluetoothgatt gatt,
  bluetoothgattcharacteristic characteristic) {
  log.e(tag,"oncharwrite "+gatt.getdevice().getname()
   +" write "
   +characteristic.getuuid().tostring()
   +" -> "
   +new string(characteristic.getvalue()));
 }
  };
  // device scan callback.
  private bluetoothadapter.lescancallback mlescancallback =
      new bluetoothadapter.lescancallback() {
    @override
    public void onlescan(final bluetoothdevice device, int rssi, byte[] scanrecord) {
      runonuithread(new runnable() {
        @override
        public void run() {
          mledevicelistadapter.adddevice(device);
          mledevicelistadapter.notifydatasetchanged();
        }
      });
    }
  };
  private void displaygattservices(list<bluetoothgattservice> gattservices) {
    if (gattservices == null) return;
    for (bluetoothgattservice gattservice : gattservices) {
     //-----service的字段信息-----//
     int type = gattservice.gettype();
      log.e(tag,"-->service type:"+utils.getservicetype(type));
      log.e(tag,"-->includedservices size:"+gattservice.getincludedservices().size());
      log.e(tag,"-->service uuid:"+gattservice.getuuid());
      
      //-----characteristics的字段信息-----//
      list<bluetoothgattcharacteristic> gattcharacteristics =gattservice.getcharacteristics();
      for (final bluetoothgattcharacteristic gattcharacteristic: gattcharacteristics) {
        log.e(tag,"---->char uuid:"+gattcharacteristic.getuuid());
        int permission = gattcharacteristic.getpermissions();
        log.e(tag,"---->char permission:"+utils.getcharpermission(permission));
        int property = gattcharacteristic.getproperties();
        log.e(tag,"---->char property:"+utils.getcharpropertie(property));
        byte[] data = gattcharacteristic.getvalue();
     if (data != null && data.length > 0) {
      log.e(tag,"---->char value:"+new string(data));
     }
     //uuid_key_data是可以跟蓝牙模块串口通信的characteristic
     if(gattcharacteristic.getuuid().tostring().equals(uuid_key_data)){      
      //测试读取当前characteristic数据，会触发mondataavailable.oncharacteristicread()
      mhandler.postdelayed(new runnable() {
            @override
            public void run() {
             mble.readcharacteristic(gattcharacteristic);
            }
          }, 500);
      //接受characteristic被写的通知,收到蓝牙模块的数据后会触发mondataavailable.oncharacteristicwrite()
      mble.setcharacteristicnotification(gattcharacteristic, true);
      //设置数据内容
      gattcharacteristic.setvalue("send data->");
      //往蓝牙模块写入数据
      mble.writecharacteristic(gattcharacteristic);
     }
     //-----descriptors的字段信息-----//
  list<bluetoothgattdescriptor> gattdescriptors = gattcharacteristic.getdescriptors();
  for (bluetoothgattdescriptor gattdescriptor : gattdescriptors) {
   log.e(tag, "-------->desc uuid:" + gattdescriptor.getuuid());
   int descpermission = gattdescriptor.getpermissions();
   log.e(tag,"-------->desc permission:"+ utils.getdescpermission(descpermission));
   byte[] desdata = gattdescriptor.getvalue();
   if (desdata != null && desdata.length > 0) {
   log.e(tag, "-------->desc value:"+ new string(desdata));
   }
      }
      }
    }//
  }
}

感兴趣的读者可以动手测试一下代码的运行情况，希望能对大家的android项目开发有所帮助。