关于BLE相关的知识，借助于之前做的一个应用（防丢器），在此做一个整理笔记。怕自己懒，先立个FLAG，这将是一个系列的文章：
1.准备知识：
Github上的库：Bluetooth-LE-Library—Android（虽然没有引入，但是他这个demo里有另外几个类写的很好，可直接用）
其他介绍BLE原理和工作机制的文章（本文主要从代码角度入手）
应用简要逻辑介绍： a.扫描并筛选出特定的设备，不是所有蓝牙设备都展示，只显示自家的；b.连接并写入认证信息到ble设备,该认证视定制情况，实现设备绑定；c.定时检测已绑定设备连接状态，未连接的由应用发起主动连接；d.监听蓝牙设备状态，比如设备发过来的指令、断开事件、信号强度；e.根据设备状态进行对应提醒，如断开报警，强度弱时提示距离偏大，接收到ble设备的单击事件时执行拍照（这里其实还充当了自拍器按键，但是我并没有找到直接控制系统相机快门的方法，采用的是自己搞了一个拍照界面⊙﹏⊙‖∣，有人会的话，请留言，万分感谢），接收到双击事件时手机报警（相当于寻找一时不知道丢到哪里的手机）；f.设备以及应用的一些设置，如勿扰区域、勿扰时段、记录设备定位信息等；g.最后还有一个设备升级，可自行参考CRS相关support文档。
2.权限申请以及最低API设置
这一步是很容易被忽略但又非常关键的，被这个坑到过(┬＿┬)
- 在
AndroidManifest.xml主配置文件里添加：
<!-- 蓝牙相关 -->
<uses-permission android:name="android.permission.BLUETOOTH"/>
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>
<uses-feature
android:name="android.hardware.bluetooth_le"
android:required="true"/>
- 在
build.gradle里如下设置：
defaultConfig {
applicationId "com.powerstick.beaglepro"
minSdkVersion 18
targetSdkVersion 19
versionCode 8
versionName "1.0.8"
}
3.初始化蓝牙扫描相关类并扫描、解析、展示（用到android.bluetooth.*）
1.BluetoothLeScanner.java如下
import android.bluetooth.BluetoothAdapter;
import android.os.Handler;
import com.tencent.bugly.crashreport.BuglyLog;
public class BluetoothLeScanner {
private final String TAG = "BluetoothLeScanner";
private final Handler mHandler;
private final BluetoothAdapter.LeScanCallback mLeScanCallback;
private final BluetoothUtils mBluetoothUtils;
private boolean mScanning;
public BluetoothLeScanner(final BluetoothAdapter.LeScanCallback leScanCallback, final BluetoothUtils
bluetoothUtils) {
mHandler = new Handler();
mLeScanCallback = leScanCallback;
mBluetoothUtils = bluetoothUtils;
}
public boolean isScanning() {
return mScanning;
}
public void scanLeDevice(final int duration, final boolean enable) {
if (enable) {
if (mScanning) {
return;
}
BuglyLog.d(TAG, "~ Starting Scan");
if (duration > 0) {
mHandler.postDelayed(new Runnable() {
@Override
public void run() {
BuglyLog.d(TAG, "~ Stopping Scan (timeout)");
mScanning = false;
mBluetoothUtils.getBluetoothAdapter().stopLeScan(mLeScanCallback);
}
}, duration);
}
mScanning = true;
mBluetoothUtils.getBluetoothAdapter().startLeScan(mLeScanCallback);
} else {
BuglyLog.d(TAG, "~ Stopping Scan");
mScanning = false;
mBluetoothUtils.getBluetoothAdapter().stopLeScan(mLeScanCallback);
}
}
}
2.在Activity中实例化并进行扫描
// 蓝牙信息相关
private BluetoothUtils mBluetoothUtils;
private BluetoothLeScanner mScanner;
mBluetoothUtils = new BluetoothUtils(this);
mScanner = new BluetoothLeScanner(mLeScanCallback, mBluetoothUtils);
startScan();
private void startScan() {
final boolean mIsBluetoothOn = mBluetoothUtils.isBluetoothOn();
final boolean mIsBluetoothLePresent = mBluetoothUtils.isBluetoothLeSupported();
mBluetoothUtils.askUserToEnableBluetoothIfNeeded();
if (mIsBluetoothOn && mIsBluetoothLePresent) {
mScanner.scanLeDevice(-1, true);
}
}
*以上代码没有注释应该没问题，这其中还有判断手机是否打开蓝牙的代码行，需注意。
3.解析扫描得到的结果，并根据实际需要在页面内展示
上面用到的mLeScanCallback如下：
private final BluetoothAdapter.LeScanCallback mLeScanCallback = new BluetoothAdapter.LeScanCallback() {
@Override
public void onLeScan(final BluetoothDevice device, final int rssi, final byte[] scanRecord) {
runOnUiThread(new Runnable() {
@Override
public void run() {
BuglyLog.i("--------->", "name:"+device.getName());
// 这里删减了业务逻辑，只做部分知识介绍
// 对于扫描到的设备，进行额外信息的获取，大多是为了只在扫描配对页显示自家产品，剔除一般设备
List<AdRecord> adRecord = AdRecordUtils.parseScanRecordAsList(scanRecord);
for (int i = 0; i < adRecord.size(); i++) {
AdRecord record = adRecord.get(i);
if (record.getType() == 0xFF) {
String mac = ByteUtils.byteArrayToHexString(record.getData());
// 直接获取出来的字符串形如：[AA,BB,CC...]处理成AA:BB:CC...的样子
mac = mac.replace("[", "").replace("]", "").replace(", ", ":");
BuglyLog.e("****", mac);
// 我们的设备额外信息就是MAC
if (TextUtils.equals(mac, device.getAddress())) {
// 添加到UI页面，等着点击配对
}
}
}
}
});
}
};
4.相关工具类
1.ByteUtils.java字节处理，在后面的手机与BLE设备通信处经常需要用到
import java.nio.ByteBuffer;
public class ByteUtils {
private static final String HEXES = "0123456789ABCDEF";
private ByteUtils() {
}
/**
* 字节数组转换成16进制的字符串表示: [01, 30, FF, AA]
*/
public static String byteArrayToHexString(final byte[] array) {
final StringBuilder sb = new StringBuilder();
boolean firstEntry = true;
sb.append('[');
for (final byte b : array) {
if (!firstEntry) {
sb.append(", ");
}
sb.append(HEXES.charAt((b & 0xF0) >> 4));
sb.append(HEXES.charAt((b & 0x0F)));
firstEntry = false;
}
sb.append(']');
return sb.toString();
}
/**
* 检查一个字节数组是否以另一个字节数组为开始
*
* @param array the array
* @param prefix the prefix
* @return boolean
*/
public static boolean doesArrayBeginWith(final byte[] array, final byte[] prefix) {
if (array.length < prefix.length) {
return false;
}
for (int i = 0; i < prefix.length; i++) {
if (array[i] != prefix[i]) {
return false;
}
}
return true;
}
/**
* 将一个长度为2的字节数组转为int
*/
public static int getIntFrom2ByteArray(final byte[] input) {
final byte[] result = new byte[4];
result[0] = 0;
result[1] = 0;
result[2] = input[0];
result[3] = input[1];
return ByteUtils.getIntFromByteArray(result);
}
/**
* Converts a byte to an int, preserving the sign.
* <p/>
* For example, FF will be converted to 255 and not -1.
*
* @param bite the byte
* @return the int from byte
*/
public static int getIntFromByte(final byte bite) {
return bite & 0xFF;
}
/**
* Converts a byte array to an int.
*
* @param bytes the bytes
* @return the int from byte array
*/
public static int getIntFromByteArray(final byte[] bytes) {
return ByteBuffer.wrap(bytes).getInt();
}
/**
* Converts a byte array to a long.
*
* @param bytes the bytes
* @return the long from byte array
*/
public static long getLongFromByteArray(final byte[] bytes) {
return ByteBuffer.wrap(bytes).getLong();
}
/**
* Inverts an byte array in place.
*
* @param array the array
*/
public static void invertArray(final byte[] array) {
final int size = array.length;
byte temp;
for (int i = 0; i < size / 2; i++) {
temp = array[i];
array[i] = array[size - 1 - i];
array[size - 1 - i] = temp;
}
}
}
2.AdRecordUtils.java从扫描到的设备中解析各自的额外信息
package com.powerstick.beaglepro.util;
import android.annotation.SuppressLint;
import android.util.SparseArray;
import com.afap.utils.ByteUtils;
import com.powerstick.beaglepro.model.AdRecord;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public final class AdRecordUtils {
private AdRecordUtils(){
// TO AVOID INSTANTIATION
}
public static String getRecordDataAsString(final AdRecord nameRecord) {
if (nameRecord == null) {
return "";
}
return new String(nameRecord.getData());
}
public static byte[] getServiceData(final AdRecord serviceData) {
if (serviceData == null) {
return null;
}
if (serviceData.getType() != AdRecord.TYPE_SERVICE_DATA) return null;
final byte[] raw = serviceData.getData();
//Chop out the uuid
return Arrays.copyOfRange(raw, 2, raw.length);
}
public static int getServiceDataUuid(final AdRecord serviceData) {
if (serviceData == null) {
return -1;
}
if (serviceData.getType() != AdRecord.TYPE_SERVICE_DATA) return -1;
final byte[] raw = serviceData.getData();
//Find UUID data in byte array
int uuid = (raw[1] & 0xFF) << 8;
uuid += (raw[0] & 0xFF);
return uuid;
}
/*
* Read out all the AD structures from the raw scan record
*/
public static List<AdRecord> parseScanRecordAsList(final byte[] scanRecord) {
final List<AdRecord> records = new ArrayList<>();
int index = 0;
while (index < scanRecord.length) {
final int length = scanRecord[index++];
//Done once we run out of records
if (length == 0) break;
final int type = ByteUtils.getIntFromByte(scanRecord[index]);
//Done if our record isn't a valid type
if (type == 0) break;
final byte[] data = Arrays.copyOfRange(scanRecord, index + 1, index + length);
records.add(new AdRecord(length, type, data));
//Advance
index += length;
}
return Collections.unmodifiableList(records);
}
@SuppressLint("UseSparseArrays")
public static Map<Integer, AdRecord> parseScanRecordAsMap(final byte[] scanRecord) {
final Map<Integer, AdRecord> records = new HashMap<>();
int index = 0;
while (index < scanRecord.length) {
final int length = scanRecord[index++];
//Done once we run out of records
if (length == 0) break;
final int type = ByteUtils.getIntFromByte(scanRecord[index]);
//Done if our record isn't a valid type
if (type == 0) break;
final byte[] data = Arrays.copyOfRange(scanRecord, index + 1, index + length);
records.put(type, new AdRecord(length, type, data));
//Advance
index += length;
}
return Collections.unmodifiableMap(records);
}
public static SparseArray<AdRecord> parseScanRecordAsSparseArray(final byte[] scanRecord) {
final SparseArray<AdRecord> records = new SparseArray<>();
int index = 0;
while (index < scanRecord.length) {
final int length = scanRecord[index++];
//Done once we run out of records
if (length == 0) break;
final int type = ByteUtils.getIntFromByte(scanRecord[index]);
//Done if our record isn't a valid type
if (type == 0) break;
final byte[] data = Arrays.copyOfRange(scanRecord, index + 1, index + length);
records.put(type, new AdRecord(length, type, data));
//Advance
index += length;
}
return records;
}
}
以上，基本涵盖了蓝牙设备扫描与筛选，页面如何显示要根据实际需要了。
