前言
关于低功耗的蓝牙介绍我已经做过很多了，只不过很多人不是奔着学习的目的去的，拿着源码就去运行，后面又发现连接设备后马上断开，然后不会自己看问题，这个现象就是快餐式的，你不了解里面的知识内容，自然就不知道是怎么回事，重复的问题我回答了好多次了。而我也是觉得写的有问题，本意上来说我是希望读者可以参考来写，能看一看文章内容，而结果绝大多数，看个标题看个运行效果，下载源码就运行，运行有问题就问你，没有什么思考。
针对这个情况，我决定做了系列性的Ble蓝牙App，尽可能的避免在你运行的时候出现bug，所以这是一个低功耗蓝牙工具App，可以让你了解到一些东西。注意是低功耗，不是经典蓝牙，如果你不知道两者之间的区别，建议你先了解一下。本文的效果：
正文
本文将会重新创建一个项目，功能一个一个的做，尽量的做好每一个功能的优化，下面我们创建一个名为GoodBle的项目，语言为Kotlin。
至于为什么使用Kotlin，稳固一下，不然太久不用就会生疏，文本我们讲述的是扫描，你可能回想，一个扫描有什么好写，不就是开始、结束、显示设备嘛？至于单独作为一个功能来写一篇文章嘛？那么我们带着问题来看这篇文章，看看扫描到底有没有必要这样来做。
一、基本配置
当前我们创建项目有一个MainActivity，然后我们需要打开viewBinding的开关，在app的build.gradle中的android{}闭包中添加如下代码：
buildFeatures { viewBinding true }
然后Sync Now，同步一下，开启成功。随后我们就可以在Activity中使用ViewBinding了，常规的使用方式是这样的：
class MainActivity : AppCompatActivity() { private lateinit var binding: ActivityMainBinding; override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) binding = ActivityMainBinding.inflate(layoutInflater); setContentView(binding.root) } }
在Java中封装通常采用反射的方式，在Kotlin中如果要对ViewBinding进行封装的话同时利用上Kotlin的一些特性的话，可以这样做，原文地址如下：Viewbinding使用和委托封装，感觉写得蛮好的，太久没用Kotlin了，还是看了一会才看懂，感兴趣的可以看看。
那么我们在com.llw.goodble下面创建一个base包，base包下创建BaseViewBinding.kt文件，里面的代码如下所示：
package com.llw.goodble.base import android.app.Activity import android.view.LayoutInflater import androidx.viewbinding.ViewBinding import kotlin.properties.ReadOnlyProperty import kotlin.reflect.KProperty fun <VB : ViewBinding> viewBinding(viewInflater: (LayoutInflater) -> VB): ReadOnlyProperty<Activity, VB> = ActivityViewBindingProperty(viewInflater) class ActivityViewBindingProperty<VB : ViewBinding>( private val viewInflater: (LayoutInflater) -> VB ) : ReadOnlyProperty<Activity, VB> { private var binding: VB? = null override fun getValue(thisRef: Activity, property: KProperty<*>): VB { return binding ?: viewInflater(thisRef.layoutInflater).also { thisRef.setContentView(it.root) binding = it } } }
通过委托的方式进行封装，下面来看在MainActivity中怎么使用它，
class MainActivity : AppCompatActivity() { private val binding by viewBinding(ActivityMainBinding::inflate) override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) } }
使用起来很简单，后面就采用这种方式，你可以运行一下，看看有没有问题，然后我们可以再创建一个ScanActivity类，用于扫描页面，修改一下activity_main.xml中的代码，如下所示：
<?xml version="1.0" encoding="utf-8"?> <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity"> <com.google.android.material.appbar.MaterialToolbar android:id="@+id/toolbar" android:layout_width="match_parent" android:layout_height="?attr/actionBarSize" android:background="@color/orange" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" app:navigationIcon="@drawable/ic_scan_ble" app:title="GoodBle" app:titleCentered="true" app:titleTextColor="@color/white" /> </androidx.constraintlayout.widget.ConstraintLayout>
这里用到了图标，代码如下所示：
<vector xmlns:android="http://schemas.android.com/apk/res/android" android:width="32dp" android:height="32dp" android:viewportWidth="1024" android:viewportHeight="1024"> <path android:fillColor="#ffffff" android:pathData="M761.5,141.1c-14.3,-9.6 -33.6,-5.9 -43.2,8.4 -9.6,14.2 -5.9,33.6 8.4,43.2 106,71.6 169.3,190.7 169.3,318.4 0,211.7 -172.2,384 -384,384S128,722.9 128,511.1c0,-127.8 63.3,-246.8 169.3,-318.4 14.2,-9.6 18,-29 8.4,-43.2s-29,-18 -43.2,-8.4C139.3,224.4 65.7,362.7 65.7,511.1c0,246.1 200.2,446.2 446.2,446.2S958.2,757.2 958.2,511.1C958.2,362.7 884.6,224.4 761.5,141.1z" /> <path android:fillColor="#ffffff" android:pathData="M402.1,157.6c17.2,0 31.1,-13.9 31.1,-31.1L433.2,96c0,-17.2 -13.9,-31.1 -31.1,-31.1s-31.1,13.9 -31.1,31.1l0,30.4C371,143.6 384.9,157.6 402.1,157.6z" /> <path android:fillColor="#ffffff" android:pathData="M624.3,157.6c17.2,0 31.1,-13.9 31.1,-31.1L655.5,96c0,-17.2 -13.9,-31.1 -31.1,-31.1s-31.1,13.9 -31.1,31.1l0,30.4C593.2,143.6 607.1,157.6 624.3,157.6z" /> <path android:fillColor="#ffffff" android:pathData="M428.3,227.4c11.2,18 41.8,48.4 85.9,48.4 43.8,0 74.9,-30.2 86.3,-48.1 9.3,-14.5 5.1,-33.7 -9.4,-43 -14.5,-9.3 -33.7,-5 -43,9.4 -0.1,0.2 -13.3,19.4 -33.9,19.4 -19.9,0 -32.3,-18 -33.2,-19.3 -9.1,-14.4 -28.2,-18.7 -42.7,-9.7C423.7,193.6 419.2,212.8 428.3,227.4z" /> <path android:fillColor="#ffffff" android:pathData="M306,440.9c-9.2,14.5 -4.8,33.8 9.7,42.9l142.7,90.1L314.1,665.1c-14.5,9.2 -18.9,28.4 -9.7,42.9 5.9,9.4 16,14.5 26.3,14.5 5.7,0 11.4,-1.6 16.6,-4.8l135.7,-85.7 0,148c0,10.6 4,20.2 10.3,27.8 0.4,0.5 0.8,1 1.2,1.4 8.4,9.3 20.5,15.3 34.1,15.3 2.4,0 4.8,-0.3 7,-0.9 5.8,-0.9 11.4,-2.8 16.5,-5.8 0.8,-0.5 1.6,-1 2.3,-1.5l134,-96.2c12.7,-8.2 20.5,-22.2 20.6,-37.2 0,-15.5 -8.4,-30.1 -21.2,-37.7l-113,-71.4 110.6,-69.9c13.6,-8.1 22,-22.8 21.9,-38.3 -0.1,-15 -8,-29 -20.7,-37.1l-132.4,-94.4c-0.8,-0.6 -1.6,-1.1 -2.5,-1.6 -21,-12.1 -47.9,-6.1 -61.4,13.7 -2.5,3.7 -4.1,7.8 -4.8,11.9 -1.7,3.9 -2.7,8.1 -2.7,12.7l0,144.9 -134.1,-84.7C334.4,422 315.2,426.4 306,440.9zM545.3,746.4 L545.3,628.9l87.1,55L545.3,746.4zM630.7,465.1l-85.4,53.9L545.3,404.3 630.7,465.1z" /> </vector>
颜色值，在colors.xml中增加：
<color name="orange">#FF5722</color> <color name="warm_yellow">#FFC107</color> <color name="dark_orange">#FF9800</color> <color name="light_orange">#FFF3E0</color> <color name="gray_white">#F8F8F8</color> <color name="gray">#989898</color>
这里给toolbar设置导航图标，点击这个导航到扫描页面，不过再次之前我们可以在base包下再创建一个BaseActivity，这里面可以写一些常用的函数，代码如下所示：
open class BaseActivity : AppCompatActivity() { private var context: Context? = null override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) context = this } protected fun jumpActivity(clazz: Class<*>?, finish: Boolean = false) { startActivity(Intent(context, clazz)) if (finish) finish() } protected fun back(toolbar: Toolbar, finish: Boolean = false) = toolbar.setNavigationOnClickListener { if (finish) finish() else onBackPressed() } protected fun showMsg(msg: CharSequence) = Toast.makeText(context, msg, Toast.LENGTH_SHORT).show() protected open fun isAndroid12() = Build.VERSION.SDK_INT >= Build.VERSION_CODES.S protected open fun hasAccessFineLocation() = hasPermission(Manifest.permission.ACCESS_FINE_LOCATION) protected open fun hasCoarseLocation() = hasPermission(Manifest.permission.ACCESS_COARSE_LOCATION) @RequiresApi(Build.VERSION_CODES.S) protected open fun hasBluetoothConnect() = hasPermission(Manifest.permission.BLUETOOTH_CONNECT) @RequiresApi(Build.VERSION_CODES.S) protected open fun hasBluetoothScan() = hasPermission(Manifest.permission.BLUETOOTH_SCAN) /** * 检查是有拥有某权限 * * @param permission 权限名称 * @return true 有 false 没有 */ protected open fun hasPermission(permission: String) = checkSelfPermission(permission) == PackageManager.PERMISSION_GRANTED /** * 蓝牙是否打开 * * @return true or false */ protected open fun isOpenBluetooth(): Boolean { (getSystemService(BLUETOOTH_SERVICE) as BluetoothManager).also { it.adapter ?: return false return it.adapter.isEnabled } } /** * 位置是否打开 */ protected open fun isOpenLocation(): Boolean { val locationManager = getSystemService(LOCATION_SERVICE) as LocationManager val gps = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER) val network = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER) val locationEnabled = isLocationEnabled() Log.d("TAG", "gps: $gps，network：$network，locationEnabled：$locationEnabled") return gps || network || locationEnabled } open fun isLocationEnabled(): Boolean { val locationMode = try { Settings.Secure.getInt(contentResolver, Settings.Secure.LOCATION_MODE) } catch (e: SettingNotFoundException) { e.printStackTrace() return false } return locationMode != Settings.Secure.LOCATION_MODE_OFF } }
这里面就是一些比较基础的方法，在后面扫描页面会用到的，然后再修改一下MainActivity中的代码，继承BaseActivity，点击中跳转扫描页面：
class MainActivity : BaseActivity() { private val binding by viewBinding(ActivityMainBinding::inflate) override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) binding.toolbar.setNavigationOnClickListener { jumpActivity(ScanActivity::class.java) } } }
为了保持一样的UI效果，下面更改一下themes.xml中的代码，如下所示：
<resources xmlns:tools="http://schemas.android.com/tools"> <!-- Base application theme. --> <style name="Theme.GoodBle" parent="Theme.MaterialComponents.DayNight.NoActionBar"> <!-- Primary brand color. --> <item name="colorPrimary">@color/orange</item> <item name="colorPrimaryVariant">@color/orange</item> <item name="colorOnPrimary">@color/white</item> <!-- Secondary brand color. --> <item name="colorSecondary">@color/light_orange</item> <item name="colorSecondaryVariant">@color/dark_orange</item> <item name="colorOnSecondary">@color/white</item> <!-- Status bar color. --> <item name="android:statusBarColor">?attr/colorPrimaryVariant</item> <!-- Customize your theme here. --> <item name="android:windowBackground">@color/gray_white</item> </style> <style name="BottomSheetDialogStyle" parent="Theme.Design.BottomSheetDialog"> <item name="android:windowFrame">@null</item> <item name="android:windowIsFloating">true</item> <item name="android:windowIsTranslucent">true</item> <item name="android:background">@android:color/transparent</item> <item name="android:backgroundDimEnabled">true</item> <item name="android:colorBackground">@android:color/transparent</item> </style> </resources>
主要就是修改状态栏颜色，窗口默认背景颜色，现在前置的条件都准备的差不多了，运行一下看看MainActivity的页面效果。
二、扫描准备
下面在com.llw.goodble包下新建一个ble包，里面我们需要创建一些类来处理扫描的相关事务，首先在ble包下创建一个BleCore类，里面先不写内容，然后我们在ble包下新建一个scan包。在scan包下新建一个BleScanCallback接口，这是一个扫描回调接口，代码如下所示：
interface BleScanCallback { /** * 扫描结果 */ fun onScanResult(result: ScanResult) /** * 批量扫描结果 */ fun onBatchScanResults(results: List<ScanResult>) {} /** * 扫描错误 */ fun onScanFailed(failed: String) {} }
同时在扫描页面需要监听一下蓝牙和定位是否打开，在scan包下添加一个广播接收器的ReceiverCallback 接口，代码如下所示：
interface ReceiverCallback { /** * 蓝牙关闭 */ fun bluetoothClose() /** * 位置关闭 */ fun locationClose() }
下面在scan创建广播接收器ScanReceiver，代码如下所示：
class ScanReceiver : BroadcastReceiver() { private var callback: ReceiverCallback? = null fun setCallback(callback: ReceiverCallback?) { this.callback = callback } private var isSend = 0 override fun onReceive(context: Context, intent: Intent) { val action = intent.action if (action == BluetoothAdapter.ACTION_STATE_CHANGED) { when (intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, BluetoothAdapter.ERROR)) { BluetoothAdapter.STATE_OFF -> Log.d(TAG, "STATE_OFF Phone bluetooth off") BluetoothAdapter.STATE_TURNING_OFF -> { callback!!.bluetoothClose() Log.d(TAG, "STATE_TURNING_OFF Phone bluetooth is turning off") } BluetoothAdapter.STATE_ON -> Log.d(TAG, "STATE_ON Phone bluetooth turned on") BluetoothAdapter.STATE_TURNING_ON -> Log.d(TAG, "STATE_TURNING_ON Phone bluetooth is on") } } else if (action == LocationManager.PROVIDERS_CHANGED_ACTION) { if (!isGPSOpen(context)) { isSend++ if (isSend == 1) { Log.d(TAG, "Positioning off") callback!!.locationClose() } else if (isSend == 4) { isSend = 0 } } } } companion object { val TAG: String = ScanReceiver::class.java.simpleName fun isGPSOpen(context: Context): Boolean { val locationMode = try { Settings.Secure.getInt(context.contentResolver, Settings.Secure.LOCATION_MODE) } catch (e: SettingNotFoundException) { e.printStackTrace() return false } return locationMode != Settings.Secure.LOCATION_MODE_OFF } } }
这里的代码相对简单就是广播接收器接收相关的动作信息，再进行回调，然后我们写一个用于扫描类，在scan包下新建一个BleScan类，代码如下所示：
/** * 低功耗扫描类 */ @SuppressLint("MissingPermission", "InlinedApi") class BleScan private constructor(private val context: Context) { private var mScanFilters: List<ScanFilter> private var mScanSettings: ScanSettings private var bleScanCallback: BleScanCallback? = null var mIsScanning = false init { mScanFilters = ArrayList() mScanSettings = ScanSettings.Builder().build() } companion object { @SuppressLint("StaticFieldLeak") @Volatile private var instance: BleScan? = null private var mBluetoothAdapter: BluetoothAdapter? = null private var mScanner: BluetoothLeScanner? = null fun getInstance(context: Context) = instance ?: synchronized(this) { instance ?: BleScan(context).also { instance = it val manager = context.getSystemService(Context.BLUETOOTH_SERVICE) as BluetoothManager mBluetoothAdapter = manager.adapter if (mBluetoothAdapter != null) { mScanner = mBluetoothAdapter?.bluetoothLeScanner } } } } /** * 设置扫描过滤 */ fun setScanFilters(scanFilters: List<ScanFilter>) { mScanFilters = scanFilters } /** * 设置扫描设置选项 */ fun setScanSettings(scanSettings: ScanSettings) { mScanSettings = scanSettings } /** * 设置扫描回调 */ fun setPhyScanCallback(bleScanCallback: BleScanCallback?) { this.bleScanCallback = bleScanCallback } fun isScanning() = mIsScanning /** * 扫描回调 */ private val scanCallback: ScanCallback = object : ScanCallback() { override fun onScanResult(callbackType: Int, result: ScanResult) { bleScanCallback?.onScanResult(result) } override fun onBatchScanResults(results: List<ScanResult>) { bleScanCallback?.onBatchScanResults(results) } override fun onScanFailed(errorCode: Int) { localScanFailed( when (errorCode) { SCAN_FAILED_ALREADY_STARTED -> "Fails to start scan as BLE scan with the same settings is already started by the app." SCAN_FAILED_APPLICATION_REGISTRATION_FAILED -> "Fails to start scan as app cannot be registered." SCAN_FAILED_INTERNAL_ERROR -> "Fails to start scan due an internal error" SCAN_FAILED_FEATURE_UNSUPPORTED -> "Fails to start power optimized scan as this feature is not supported." else -> "UNKNOWN_ERROR" } ) } } /** * 显示本地扫描错误 */ private fun localScanFailed(failed: String) = bleScanCallback?.onScanFailed(failed) /** * 开始扫描 */ @SuppressLint("MissingPermission") fun startScan() { if (!isOpenBluetooth()) { localScanFailed("Bluetooth is not turned on.") return } if (isAndroid12()) { if (!hasBluetoothScan()) { localScanFailed("Android 12 needs to dynamically request bluetooth scan permission.") return } } else { if (!hasAccessFineLocation()) { localScanFailed("Android 6 to 12 requires dynamic request location permission.") return } } if (mIsScanning) { localScanFailed("Currently scanning, please close the current scan and scan again.") return } if (mScanner == null) mScanner = mBluetoothAdapter?.bluetoothLeScanner if (!mBluetoothAdapter!!.isEnabled) { localScanFailed("Bluetooth not turned on.") return } mScanner?.startScan(mScanFilters, mScanSettings, scanCallback) mIsScanning = true } /** * 停止扫描 */ fun stopScan() { if (!mIsScanning) { localScanFailed("Not currently scanning, your stop has no effect.") return } if (mScanner == null) { localScanFailed("BluetoothLeScanner is Null.") return } if (!mBluetoothAdapter!!.isEnabled) { localScanFailed("Bluetooth not turned on.") return } mIsScanning = false mScanner?.stopScan(scanCallback) } /** * 是否打开蓝牙 */ private fun isOpenBluetooth() = if (mBluetoothAdapter == null) { localScanFailed("BluetoothAdapter is Null."); false } else mBluetoothAdapter!!.isEnabled private fun isAndroid12() = Build.VERSION.SDK_INT >= Build.VERSION_CODES.S private fun hasAccessFineLocation() = hasPermission(Manifest.permission.ACCESS_FINE_LOCATION) private fun hasBluetoothConnect() = hasPermission(Manifest.permission.BLUETOOTH_CONNECT) private fun hasBluetoothScan() = hasPermission(Manifest.permission.BLUETOOTH_SCAN) private fun hasPermission(permission: String) = context.checkSelfPermission(permission) == PackageManager.PERMISSION_GRANTED }
这里首先是创建一个单例，在里面对当前类和一些变量进行初始化，核心就是一个扫描回调，开始和停止扫描的方法处理。因为后面还需要写Ble相关的数据处理，因此在ble包下创建一个BleCore类，代码如下所示：
class BleCore private constructor(private val context: Context) { @SuppressLint("StaticFieldLeak") companion object { @SuppressLint("StaticFieldLeak") @Volatile private var instance: BleCore? = null @SuppressLint("StaticFieldLeak") private lateinit var bleScan: BleScan fun getInstance(context: Context) = instance ?: synchronized(this) { instance ?: BleCore(context).also { instance = it //蓝牙扫描 bleScan = BleScan.getInstance(context) } } } fun setPhyScanCallback(bleScanCallback: BleScanCallback) { bleScan.setPhyScanCallback(bleScanCallback) } fun isScanning() = bleScan.isScanning() fun startScan() = bleScan.startScan() fun stopScan() = bleScan.stopScan() }
同样是一个单例，在里面初始化BleScan，然后增加几个函数去调用BleScan中的函数，最后我们在com.llw.goodble包下创建一个BleApp类，代码如下所示：
class BleApp : Application() { @SuppressLint("StaticFieldLeak") private lateinit var context: Context @SuppressLint("StaticFieldLeak") private lateinit var bleCore: BleCore override fun onCreate() { super.onCreate() context = applicationContext //初始化Ble核心库 bleCore = BleCore.getInstance(this) } fun getBleCore() = bleCore }
这里继承Application，通过自定义的方式在App启动的时候加载这个类，然后在onCreate()函数中，完成对于Ble核心类的初始化，顺便完成对于Ble扫描类的初始化。最后在AndroidManifest.xml中的application标签中配置这个BleApp，如下所示：
<application android:name=".BleApp" ...>
三、扫描页面
在Android12及以上版本，使用蓝牙时需要请求扫描、连接权限、如果还需要使用手机作为从机的话，就请求广播权限，后面会提到的，同时在低版本Android中我们扫描蓝牙请求定位权限，那么首先我们就把权限的部分先做了。
首先声明静态权限，在AndroidManifest.xml中增加如下代码：
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" /> <uses-permission android:name="android.permission.BLUETOOTH" /> <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" /> <uses-permission android:name="android.permission.BLUETOOTH_CONNECT" /> <uses-permission android:name="android.permission.BLUETOOTH_SCAN" /> <uses-feature android:name="android.hardware.bluetooth_le"/>
① 增加UI布局
动态权限请求有两种方式，一种是进入这个页面一下子请求多个权限，另一种是一个一个来请求，让你知道为什么会请求这个权限，这里我们选择第二种，因此需要增加一些布局xml，如下图所示的布局XML。
下面我们依次创建，lay_android12_should_connect.xml
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" android:id="@+id/request_location_lay" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@color/gray_white" android:gravity="center" android:orientation="vertical" android:paddingStart="16dp" android:paddingEnd="16dp"> <ImageView android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center_horizontal" android:padding="16dp" android:src="@drawable/ic_bluetooth_connected" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="需要蓝牙连接权限" android:textColor="@color/dark_orange" android:textSize="16sp" /> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="16dp" android:layout_marginBottom="16dp" android:text="从Android12.0开始，打开蓝牙之前需要请求此权限，使用蓝牙连接权限" app:titleTextColor="@color/black" /> <com.google.android.material.button.MaterialButton android:id="@+id/btn_request_connect_permission" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center_horizontal" android:text="授予权限" android:textColor="@color/white" /> </LinearLayout>
用到一个图标ic_bluetooth_connected.xml
<?xml version="1.0" encoding="UTF-8" standalone="no"?> <vector xmlns:android="http://schemas.android.com/apk/res/android" android:width="48dp" android:height="48dp" android:tint="@color/orange" android:viewportWidth="24.0" android:viewportHeight="24.0"> <path android:fillColor="@android:color/white" android:pathData="M7,12l-2,-2 -2,2 2,2 2,-2zM17.71,7.71L12,2h-1v7.59L6.41,5 5,6.41 10.59,12 5,17.59 6.41,19 11,14.41L11,22h1l5.71,-5.71 -4.3,-4.29 4.3,-4.29zM13,5.83l1.88,1.88L13,9.59L13,5.83zM14.88,16.29L13,18.17v-3.76l1.88,1.88zM19,10l-2,2 2,2 2,-2 -2,-2z" /> </vector>
布局lay_android12_should_scan.xml
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" android:id="@+id/request_location_lay" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@color/gray_white" android:gravity="center" android:orientation="vertical" android:paddingStart="16dp" android:paddingEnd="16dp"> <ImageView android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center_horizontal" android:padding="16dp" android:src="@drawable/ic_bluetooth_scan" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="需要扫描权限" android:textColor="@color/dark_orange" android:textSize="16sp" /> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="16dp" android:layout_marginBottom="16dp" android:text="从Android12.0开始，扫描设备不再需要请求定位权限，使用此权限" app:titleTextColor="@color/black" /> <com.google.android.material.button.MaterialButton android:id="@+id/btn_request_scan_permission" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center_horizontal" android:text="授予权限" android:textColor="@color/white" /> </LinearLayout>
图标ic_bluetooth_scan.xml
<?xml version="1.0" encoding="UTF-8" standalone="no"?> <vector xmlns:android="http://schemas.android.com/apk/res/android" android:width="48dp" android:height="48dp" android:autoMirrored="true" android:tint="@color/orange" android:viewportWidth="24.0" android:viewportHeight="24.0"> <path android:fillColor="@android:color/white" android:pathData="M14.24,12.01l2.32,2.32c0.28,-0.72 0.44,-1.51 0.44,-2.33 0,-0.82 -0.16,-1.59 -0.43,-2.31l-2.33,2.32zM19.53,6.71l-1.26,1.26c0.63,1.21 0.98,2.57 0.98,4.02s-0.36,2.82 -0.98,4.02l1.2,1.2c0.97,-1.54 1.54,-3.36 1.54,-5.31 -0.01,-1.89 -0.55,-3.67 -1.48,-5.19zM15.71,7.71L10,2L9,2v7.59L4.41,5 3,6.41 8.59,12 3,17.59 4.41,19 9,14.41L9,22h1l5.71,-5.71 -4.3,-4.29 4.3,-4.29zM11,5.83l1.88,1.88L11,9.59L11,5.83zM12.88,16.29L11,18.17v-3.76l1.88,1.88z" /> </vector>
布局lay_empty.xml：
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent" android:layout_height="match_parent" android:gravity="center" android:orientation="vertical"> <ImageView android:id="@+id/imageView" android:layout_width="100dp" android:layout_height="100dp" app:srcCompat="@mipmap/ic_scanning" /> <TextView android:id="@+id/textView2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginTop="24dp" android:text="努力扫描中" android:textColor="@color/gray" android:textSize="18sp" android:textStyle="bold" /> </LinearLayout>
图标不是XML图片，去源码中获取，这是在扫描不到设备的时候显示的布局，布局lay_should_enable_bluetooth.xml。
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@color/gray_white" android:gravity="center" android:orientation="vertical"> <ImageView android:layout_width="wrap_content" android:layout_height="wrap_content" android:padding="16dp" app:srcCompat="@drawable/ic_bluetooth_disabled" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:gravity="center_horizontal" android:text="蓝牙已禁用" android:textColor="@color/dark_orange" android:textSize="16sp" /> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="16dp" android:gravity="center_horizontal" android:text="蓝牙适配器已关闭，单击下面的按钮以启用它。" android:textColor="@color/black" /> <com.google.android.material.button.MaterialButton android:id="@+id/btn_enable_bluetooth" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center_horizontal" android:layout_marginTop="16dp" android:text="启用" android:textColor="@color/white" /> </LinearLayout>
图标ic_bluetooth_disabled.xml
<vector xmlns:android="http://schemas.android.com/apk/res/android" android:width="48dp" android:height="48dp" android:viewportWidth="24.0" android:viewportHeight="24.0"> <path android:fillColor="@color/orange" android:pathData="M13,5.83l1.88,1.88 -1.6,1.6 1.41,1.41 3.02,-3.02L12,2h-1v5.03l2,2v-3.2zM5.41,4L4,5.41 10.59,12 5,17.59 6.41,19 11,14.41V22h1l4.29,-4.29 2.3,2.29L20,18.59 5.41,4zM13,18.17v-3.76l1.88,1.88L13,18.17z" /> </vector>
布局lay_should_enable_location.xml
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@color/gray_white" android:gravity="center" android:orientation="vertical"> <ImageView android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center_horizontal" android:padding="16dp" app:srcCompat="@drawable/ic_location_disabled" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="位置已禁用" android:textColor="@color/dark_orange" android:textSize="16sp" /> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="16dp" android:gravity="center_horizontal" android:text="位置已关闭，单击下面的按钮以启用它。" android:textColor="@color/black" /> <com.google.android.material.button.MaterialButton android:id="@+id/btn_enable_location" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center_horizontal" android:layout_marginTop="16dp" android:text="启用" android:textColor="@color/white" /> </LinearLayout>
图标ic_location_disabled.xml
<?xml version="1.0" encoding="UTF-8" standalone="no"?> <vector xmlns:android="http://schemas.android.com/apk/res/android" android:width="48dp" android:height="48dp" android:tint="@color/orange" android:viewportWidth="24.0" android:viewportHeight="24.0"> <path android:fillColor="@android:color/white" android:pathData="M20.94,11c-0.46,-4.17 -3.77,-7.48 -7.94,-7.94L13,1h-2v2.06c-1.13,0.12 -2.19,0.46 -3.16,0.97l1.5,1.5C10.16,5.19 11.06,5 12,5c3.87,0 7,3.13 7,7 0,0.94 -0.19,1.84 -0.52,2.65l1.5,1.5c0.5,-0.96 0.84,-2.02 0.97,-3.15L23,13v-2h-2.06zM3,4.27l2.04,2.04C3.97,7.62 3.25,9.23 3.06,11L1,11v2h2.06c0.46,4.17 3.77,7.48 7.94,7.94L11,23h2v-2.06c1.77,-0.2 3.38,-0.91 4.69,-1.98L19.73,21 21,19.73 4.27,3 3,4.27zM16.27,17.54C15.09,18.45 13.61,19 12,19c-3.87,0 -7,-3.13 -7,-7 0,-1.61 0.55,-3.09 1.46,-4.27l9.81,9.81z" /> </vector>
布局lay_should_location_lay.xml
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" android:id="@+id/request_location_lay" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@color/gray_white" android:gravity="center" android:orientation="vertical" android:paddingStart="16dp" android:paddingEnd="16dp"> <ImageView android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center_horizontal" android:padding="16dp" android:src="@drawable/ic_location_off" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="需要位置许可" android:textColor="@color/dark_orange" android:textSize="16sp" /> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="16dp" android:layout_marginBottom="16dp" android:text="从 Android 6.0 Marshmallow 开始，应用程序需要位置权限才能扫描低功耗蓝牙设备。" /> <com.google.android.material.button.MaterialButton android:id="@+id/btn_request_location_permission" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center_horizontal" android:text="授予权限" android:textColor="@color/white" /> </LinearLayout>
图标ic_location_off.xml
<vector xmlns:android="http://schemas.android.com/apk/res/android" android:width="48dp" android:height="48dp" android:viewportWidth="24.0" android:viewportHeight="24.0"> <path android:fillColor="@color/orange" android:pathData="M12,6.5c1.38,0 2.5,1.12 2.5,2.5 0,0.74 -0.33,1.39 -0.83,1.85l3.63,3.63c0.98,-1.86 1.7,-3.8 1.7,-5.48 0,-3.87 -3.13,-7 -7,-7 -1.98,0 -3.76,0.83 -5.04,2.15l3.19,3.19c0.46,-0.52 1.11,-0.84 1.85,-0.84zM16.37,16.1l-4.63,-4.63 -0.11,-0.11L3.27,3 2,4.27l3.18,3.18C5.07,7.95 5,8.47 5,9c0,5.25 7,13 7,13s1.67,-1.85 3.38,-4.35L18.73,21 20,19.73l-3.63,-3.63z" /> </vector>
好了，在我们的努力下这些布局总算是创建完成了，下面我们将它们放置到activity_scan.xml中，代码如下所示：
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".ScanActivity"> <com.google.android.material.appbar.MaterialToolbar android:id="@+id/toolbar" android:layout_width="match_parent" android:layout_height="?attr/actionBarSize" android:background="@color/orange" app:title="选择蓝牙设备" app:titleTextColor="@color/white"> <TextView android:id="@+id/tv_scan_status" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="end" android:layout_marginEnd="6dp" android:padding="10dp" android:text="搜索" android:textColor="@color/white" android:textSize="14sp" android:visibility="gone" /> </com.google.android.material.appbar.MaterialToolbar> <ProgressBar android:id="@+id/pb_scan_loading" style="?android:attr/progressBarStyleHorizontal" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_alignBottom="@+id/toolbar" android:layout_marginBottom="-10dp" android:indeterminate="true" android:indeterminateTint="@color/orange" android:visibility="invisible" /> <!--设备列表--> <androidx.recyclerview.widget.RecyclerView android:id="@+id/rv_device" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_below="@+id/toolbar" android:layout_marginTop="4dp" android:overScrollMode="never" /> <!--未扫描到设备时显示--> <include android:id="@+id/empty_lay" layout="@layout/lay_empty" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_below="@id/toolbar" /> <!-- Android 12蓝牙扫描权限为许可时显示 Shell_Unresponsive--> <include android:id="@+id/request_bluetooth_scan_lay" layout="@layout/lay_android12_should_scan" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_below="@id/toolbar" android:visibility="gone" /> <!--Android 6 至 11 没有打开位置开关 无法扫描蓝牙--> <include android:id="@+id/enable_location_lay" layout="@layout/lay_should_enable_location" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_below="@id/toolbar" android:visibility="gone" /> <!-- 位置权限未许可时显示 --> <include android:id="@+id/request_location_lay" layout="@layout/lay_should_location_lay" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_below="@id/toolbar" android:visibility="gone" /> <!-- 手机蓝牙未开启时显示 --> <include android:id="@+id/enable_bluetooth_lay" layout="@layout/lay_should_enable_bluetooth" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_below="@id/toolbar" android:visibility="gone" /> <!-- Android12 开启蓝牙需要先请求蓝牙连接权限 --> <include android:id="@+id/request_bluetooth_connect_lay" layout="@layout/lay_android12_should_connect" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_below="@id/toolbar" android:visibility="gone" /> </RelativeLayout>
下面我们可以写代码了，在ScanActivity中，
Android Ble蓝牙App（一）扫描（下）https://developer.aliyun.com/article/1407785
