App蓝牙通讯技术

本文介绍了App中蓝牙通讯技术的基础知识,包括中心设备与外围设备的角色、数据结构和服务特性。详细阐述了iOS和Android平台上蓝牙连接、扫描服务、数据交互及优化点。蓝牙通讯主要应用于设备间的数据交换,如心率监测、温度控制等场景。

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引言

蓝牙是设备近距离通信的一种方便手段,在App引入蓝牙4.0后,设备之间的通讯变得更加简单。通过蓝牙进行通讯交互分为两方,一方为中心设备central,一方为外设 peripheral,外设通过广播的方式向外发送信息,中心设备检索到外设发的广播信息,可以进行配对连接,进而进行数据交互。
具体实践: Swift项目中快速集成蓝牙(Ble4.0)

基础知识点

  • 经典蓝牙和低能耗蓝牙(BLE)
    蓝牙一般分为传统蓝牙和BLE两种模式:传统蓝牙可以传输音频等较大数据量,距离近、功耗相对大;而BLE则用来传输节点数据,传输数据量十分小,多数情况处于休眠状态,因而功耗十分低。下图是经典蓝牙和BLE对比图。

  • 蓝牙常见名称和缩写
    • BLE:(Bluetooth low energy)蓝牙低能耗
    • Central:中心设备,发起蓝牙连接的设备(一般是指手机)
    • Peripheral:外设,被蓝牙连接的设备(心率感应器)
    • Service and Characteristic:服务和特征,每个设备会提供服务和特征,类似于服务端的API,但是结构不同,每个设备会有很多服务,每个服务中包含很多特征,这些特征的权限一般分为读(read),写(write),通知(notify)几种,就是我们连接设备后具体需要操作的内容
    • Description:描述,每个Characteristic可以对应一个或者多个Description用于描述Characteristic的信息或属性

安卓蓝牙APP通讯。package com.mt.truthblue2_1; import java.util.ArrayList; import java.util.List; import com.mt.mtblesdk.MTBeacon; import com.mt.tools.Tools; import com.mt.truthblue2_1.BLEService.LocalBinder; import android.annotation.SuppressLint; import android.app.Activity; import android.bluetooth.BluetoothAdapter; import android.bluetooth.BluetoothDevice; import android.content.ComponentName; import android.content.Context; import android.content.Intent; import android.content.ServiceConnection; import android.os.Bundle; import android.os.Handler; import android.os.IBinder; import android.os.Message; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.AdapterView; import android.widget.AdapterView.OnItemClickListener; import android.widget.BaseAdapter; import android.widget.ListView; import android.widget.TextView; public class MainActivity extends Activity { private final static int REQUEST_ENABLE_BT = 2001; private ServiceConnection connection = new ServiceConnection() { @Override public void onServiceDisconnected(ComponentName name) { } @Override public void onServiceConnected(ComponentName name, IBinder service) { LocalBinder binder = (LocalBinder) service; Tools.mBLEService = binder.getService(); if (Tools.mBLEService.initBle()) { // scanBle(); // 开始扫描设备 if (!Tools.mBLEService.mBluetoothAdapter.isEnabled()) { final Intent enableBtIntent = new Intent( BluetoothAdapter.ACTION_REQUEST_ENABLE); startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT); } else { scanBle(); // 开始扫描设备 } } } }; @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); if (requestCode == REQUEST_ENABLE_BT) { if (resultCode == RESULT_OK) { scanBle(); // 开始扫描设备 } else { // finish(); } } } @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); initView(); bindService(new Intent(this, BLEService.class), connection, Context.BIND_AUTO_CREATE); } // 初始化控件 private LayoutInflater mInflater; private ListView ble_listview; private List<MTBeacon> scan_devices = new ArrayList<MTBeacon>(); private List<MTBeacon> scan_devices_dis = new ArrayList<MTBeacon>(); private BaseAdapter list_adapter = new BaseAdapter() { @SuppressLint("InflateParams") @Override public View getView(int position, View convertView, ViewGroup parent) { if (null == convertView) { convertView = mInflater.inflate(R.layout.devicefmt, null); } TextView device_name_txt = (TextView) convertView .findViewById(R.id.device_name_txt); TextView device_rssi_txt = (TextView) convertView .findViewById(R.id.device_rssi_txt); TextView device_mac_txt = (TextView) convertView .findViewById(R.id.device_mac_txt); device_name_txt.setText(getItem(position).GetDevice().getName()); device_mac_txt.setText("Mac: " + getItem(position).GetDevice().getAddress()); device_rssi_txt.setText("Rssi: " + getItem(position).GetAveragerssi()); return convertView; } @Override public long getItemId(int position) { return position; } @Override public MTBeacon getItem(int position) { return scan_devices_dis.get(position); } @Override public int getCount() { return scan_devices_dis.size(); } }; private void initView() { mInflater = LayoutInflater.from(this); ble_listview = (ListView) findViewById(R.id.ble_listview); ble_listview.setAdapter(list_adapter); ble_listview.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { // scan_flag = false; // Tools.mBLEService.stopscanBle(mLeScanCallback); Intent intent = new Intent(getApplicationContext(), ServiceActivity.class); intent.putExtra("device", scan_devices_dis.get(position) .GetDevice()); startActivity(intent); } }); } // 开始扫描 private int scan_timer_select = 0; private boolean scan_flag = true; private Handler search_timer = new Handler() { @Override public void handleMessage(Message msg) { super.handleMessage(msg); search_timer.sendEmptyMessageDelayed(0, 500); if (!scan_flag) { return; } if (!Tools.mBLEService.mBluetoothAdapter.isEnabled()) { return; } // 扫描时间调度 switch (scan_timer_select) { case 1: // 开始扫描 Tools.mBLEService.scanBle(mLeScanCallback); break; case 3: // 停止扫描(结算) Tools.mBLEService.stopscanBle(mLeScanCallback); // 停止扫描 for (int i = 0; i < scan_devices.size();) { // 防抖 if (scan_devices.get(i).CheckSearchcount() > 2) { scan_devices.remove(i); } else { i++; } } scan_devices_dis.clear(); // 显示出来 for (MTBeacon device : scan_devices) { scan_devices_dis.add(device); } list_adapter.notifyDataSetChanged(); break; default: break; } scan_timer_select = (scan_timer_select + 1) % 4; } }; private BluetoothAdapter.LeScanCallback mLeScanCallback = new BluetoothAdapter.LeScanCallback() { @Override public void onLeScan(BluetoothDevice device, int rssi, byte[] scanRecord) { int i = 0; // 检查是否是搜索过的设备,且更新 for (i = 0; i < scan_devices.size(); i++) { if (0 == device.getAddress().compareTo( scan_devices.get(i).GetDevice().getAddress())) { scan_devices.get(i).ReflashInf(device, rssi, scanRecord); // 更新信息 return; } } // 增加新设备 scan_devices.add(new MTBeacon(device, rssi, scanRecord)); } }; private void scanBle() { search_timer.sendEmptyMessageDelayed(0, 500); } @Override protected void onPause() { super.onPause(); scan_flag = false; Tools.mBLEService.stopscanBle(mLeScanCallback); } @Override protected void onResume() { super.onResume(); scan_flag = true; } @Override protected void onDestroy() { super.onDestroy(); unbindService(connection); } }
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