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：
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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));
}
}
}
}//
}
}
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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。