前言

  在上一篇中我们完成了连接和发现服务两个动作，那么再发现服务之后要做什么呢？发现服务只是让你知道设备有什么服务，可以做什么事情。

正文

  本篇要做的是显示服务下的特性，首先我们了解一下特性的基本知识。在蓝牙低功耗（BLE）中，特性（Characteristic）是蓝牙设备提供的一种数据单元，用于描述设备的某个属性或功能。特性包含了一系列的属性和值，可以用于读取、写入和通知数据。

BLE特性相关的关键概念和说明：

1. UUID（Universally Unique Identifier）：每个特性都会有一个唯一的UUID，用于标识该特性。
2. 值（Value）：特性包含一个值，可以是字节数组、字符串或其他数据类型。该值代表特性的当前状态或数据内容。
3. 属性（Properties）：特性具有一组属性，包括读、写、通知等。属性决定了可以对特性进行哪些操作。
4. 读（Read）：允许外部设备从特性中读取当前的值。
5. 写（Write）：允许外部设备向特性写入一个新的值。
6. 通知（Notify）：当特性的值发生变化时，可以通过通知方式将新的值发送给订阅该特性的外部设备。
7. 描述符（Descriptor）：特性可以附带一个或多个描述符，用于提供关于特性的额外信息或配置。

  使用BLE特性，可以实现各种功能和数据交互，例如传感器数据的读取、设备状态的监控、远程控制等。特性的读写和通知操作可以通过与蓝牙设备的交互来实现。需要注意的是，BLE特性的操作和功能是由设备的厂商定义的，并在设备的GATT（Generic Attribute Profile）配置文件中进行描述。

  首先理清一下思路，我们现在知道服务下面有特性，特性下面有一些属性值，其中属性（Properties）尤为重要，因为它决定了你的特性可以进行那些操作。用一个图来说明服务，特性，属性之间的关系。

一、获取属性列表

下面我们先获取最下面的属性，这是一个列表，属性值的处理有一些不同，首先我们在BleUtils中增加一个函数，代码如下所示：

    /**
     * 获取属性
     */
    fun getProperties(property: Int): List {
        val properties: MutableList = ArrayList()
        for (i in 0..7) {
            when (property and (1 shl i)) {
                0x01 -> properties.add("Broadcast")
                0x02 -> properties.add("Read")
                0x04 -> properties.add("Write No Response")
                0x08 -> properties.add("Write")
                0x10 -> properties.add("Notify")
                0x20 -> properties.add("Indicate")
                0x40 -> properties.add("Authenticated Signed Writes")
                0x80 -> properties.add("Extended Properties")
            }
        }
        return properties
    }

  这里是通过位运算进行计算属性的值，首先是循环遍历，shl 是一种位运算符，用于执行按位左移操作。shl 是 “shift left” 的缩写。and用于执行按位与操作。先左移再按位与，得到最终的值，根据值得到属性描述，这些描述就是具体的功能操作。会返回一个属性列表，有了列表我们就可以写一个适配器了。

二、属性适配器

首先我们在layout下创建一个item_property.xml，代码如下所示：

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/tv_property"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginEnd="8dp"
    android:text="property"
    android:textColor="@color/orange" />

  因为是String类型，所以我们就直接用一个TextView显示即可，下面我们写适配器，在adapter包下新建一个PropertyAdapter类，代码如下所示：

class PropertyAdapter(
    private val properties: List,
    private val listener: OnItemClickListener
) : RecyclerView.Adapter() {

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        return ViewHolder(ItemPropertyBinding.inflate(LayoutInflater.from(parent.context), parent, false)).apply {
            binding.tvProperty.setOnClickListener { v -> listener.onItemClick(v, adapterPosition) }
        }
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        holder.binding.tvProperty.text = properties[position]
    }

    override fun getItemCount() = properties.size

    class ViewHolder(itemView: ItemPropertyBinding) : RecyclerView.ViewHolder(itemView.root) {
        var binding: ItemPropertyBinding

        init {
            binding = itemView
        }
    }
}

这里进行了属性的点击监听，我们可以回调到特性适配器中去处理，下面我们要处理的就是特性了。

三、获取特性名称

  首先是特性名称，同样是根据UUID，同样是那个PDF文档，在BleUtils中增加一个getCharacteristicsName()函数，代码有点多，如下所示：

    /**
     * 获取特性名称
     * @param uuid UUID
     */
    fun getCharacteristicsName(uuid: UUID) =
        when ("0x${uuid.toString().substring(4, 8).uppercase(Locale.getDefault())}") {
            "0x2A00" -> "Device Name"
            "0x2A01" -> "Appearance"
            "0x2A02" -> "Peripheral Privacy Flag"
            "0x2A03" -> "Reconnection Address"
            "0x2A04" -> "Peripheral Preferred Connection Parameters"
            "0x2A05" -> "Service Changed"
            "0x2A06" -> "Alert Level"
            "0x2A07" -> "Tx Power Level"
            "0x2A08" -> "Date Time"
            "0x2A09" -> "Day of Week"
            "0x2A0A" -> "Day Date Time"
            "0x2A0C" -> "Exact Time 256"
            "0x2A0D" -> "DST Offset"
            "0x2A0E" -> "Time Zone"
            "0x2A0F" -> "Local Time Information"
            "0x2A11" -> "Time with DST"
            "0x2A12" -> "Time Accuracy"
            "0x2A13" -> "Time Source"
            "0x2A14" -> "Reference Time Information"
            "0x2A16" -> "Time Update Control Point"
            "0x2A17" -> "Time Update State"
            "0x2A18" -> "Glucose Measurement"
            "0x2A19" -> "Battery Level"
            "0x2A1C" -> "Temperature Measurement"
            "0x2A1D" -> "Temperature Type"
            "0x2A1E" -> "Intermediate Temperature"
            "0x2A21" -> "Measurement Interval"
            "0x2A22" -> "Boot Keyboard Input Report"
            "0x2A23" -> "System ID"
            "0x2A24" -> "Model Number String"
            "0x2A25" -> "Serial Number String"
            "0x2A26" -> "Firmware Revision String"
            "0x2A27" -> "Hardware Revision String"
            "0x2A28" -> "Software Revision String"
            "0x2A29" -> "Manufacturer Name String"
            "0x2A2A" -> "IEEE 11073-20601 Regulatory Certification Data List"
            "0x2A2B" -> "Current Time"
            "0x2A2C" -> "Magnetic Declination"
            "0x2A31" -> "Scan Refresh"
            "0x2A32" -> "Boot Keyboard Output Report"
            "0x2A33" -> "Boot Mouse Input Report"
            "0x2A34" -> "Glucose Measurement Context"
            "0x2A35" -> "Blood Pressure Measurement"
            "0x2A36" -> "Intermediate Cuff Pressure"
            "0x2A37" -> "Heart Rate Measurement"
            "0x2A38" -> "Body Sensor Location"
            "0x2A39" -> "Heart Rate Control Point"
            "0x2A3F" -> "Alert Status"
            "0x2A40" -> "Ringer Control Point"
            "0x2A41" -> "Ringer Setting"
            "0x2A42" -> "Alert Category ID Bit Mask"
            "0x2A43" -> "Alert Category ID"
            "0x2A44" -> "Alert Notification Control Point"
            "0x2A45" -> "Unread Alert Status"
            "0x2A46" -> "New Alert"
            "0x2A47" -> "Supported New Alert Category"
            "0x2A48" -> "Supported Unread Alert Category"
            "0x2A49" -> "Blood Pressure Feature"
            "0x2A4A" -> "HID Information"
            "0x2A4B" -> "Report Map"
            "0x2A4C" -> "HID Control Point"
            "0x2A4D" -> "Report"
            "0x2A4E" -> "Protocol Mode"
            "0x2A4F" -> "Scan Interval Window"
            "0x2A50" -> "PnP ID"
            "0x2A51" -> "Glucose Feature"
            "0x2A52" -> "Record Access Control Point"
            "0x2A53" -> "RSC Measurement"
            "0x2A54" -> "RSC Feature"
            "0x2A55" -> "SC Control Point"
            "0x2A5A" -> "Aggregate"
            "0x2A5B" -> "CSC Measurement"
            "0x2A5C" -> "CSC Feature"
            "0x2A5D" -> "Sensor Location"
            "0x2A5E" -> "PLX Spot-Check Measurement"
            "0x2A5F" -> "PLX Continuous Measurement"
            "0x2A60" -> "PLX Features"
            "0x2A63" -> "Cycling Power Measurement"
            "0x2A64" -> "Cycling Power Vector"
            "0x2A65" -> "Cycling Power Feature"
            "0x2A66" -> "Cycling Power Control Point"
            "0x2A67" -> "Location and Speed"
            "0x2A68" -> "Navigation"
            "0x2A69" -> "Position Quality"
            "0x2A6A" -> "LN Feature"
            "0x2A6B" -> "LN Control Point"
            "0x2A6C" -> "Elevation"
            "0x2A6D" -> "Pressure"
            "0x2A6E" -> "Temperature"
            "0x2A6F" -> "Humidity"
            "0x2A70" -> "True Wind Speed"
            "0x2A71" -> "True Wind Direction"
            "0x2A72" -> "Apparent Wind Speed"
            "0x2A73" -> "Apparent Wind Direction"
            "0x2A74" -> "Gust Factor"
            "0x2A75" -> "Pollen Concentration"
            "0x2A76" -> "UV Index"
            "0x2A77" -> "Irradiance"
            "0x2A78" -> "Rainfall"
            "0x2A79" -> "Wind Chill"
            "0x2A7A" -> "Heat Index"
            "0x2A7B" -> "Dew Point"
            "0x2A7D" -> "Descriptor Value Changed"
            "0x2A7E" -> "Aerobic Heart Rate Lower Limit"
            "0x2A7F" -> "Aerobic Threshold"
            "0x2A80" -> "Age"
            "0x2A81" -> "Anaerobic Heart Rate Lower Limit"
            "0x2A82" -> "Anaerobic Heart Rate Upper Limit"
            "0x2A83" -> "Anaerobic Threshold"
            "0x2A84" -> "Aerobic Heart Rate Upper Limit"
            "0x2A85" -> "Date of Birth"
            "0x2A86" -> "Date of Threshold Assessment"
            "0x2A87" -> "Email Address"
            "0x2A88" -> "Fat Burn Heart Rate Lower Limit"
            "0x2A89" -> "Fat Burn Heart Rate Upper Limit"
            "0x2A8A" -> "First Name"
            "0x2A8B" -> "Five Zone Heart Rate Limits"
            "0x2A8C" -> "Gender"
            "0x2A8D" -> "Heart Rate Max"
            "0x2A8E" -> "Height"
            "0x2A8F" -> "Hip Circumference"
            "0x2A90" -> "Last Name"
            "0x2A91" -> "Maximum Recommended Heart Rate"
            "0x2A92" -> "Resting Heart Rate"
            "0x2A93" -> "Sport Type for Aerobic and Anaerobic Thresholds"
            "0x2A94" -> "Three Zone Heart Rate Limits"
            "0x2A95" -> "Two Zone Heart Rate Limits"
            "0x2A96" -> "VO2 Max"
            "0x2A97" -> "Waist Circumference"
            "0x2A98" -> "Weight"
            "0x2A99" -> "Database Change Increment"
            "0x2A9A" -> "User Index"
            "0x2A9B" -> "Body Composition Feature"
            "0x2A9C" -> "Body Composition Measurement"
            "0x2A9D" -> "Weight Measurement"
            "0x2A9E" -> "Weight Scale Feature"
            "0x2A9F" -> "User Control Point"
            "0x2AA0" -> "Magnetic Flux Density - 2D"
            "0x2AA1" -> "Magnetic Flux Density - 3D"
            "0x2AA2" -> "Language"
            "0x2AA3" -> "Barometric Pressure Trend"
            "0x2AA4" -> "Bond Management Control Point"
            "0x2AA5" -> "Bond Management Feature"
            "0x2AA6" -> "Central Address Resolution"
            "0x2AA7" -> "CGM Measurement"
            "0x2AA8" -> "CGM Feature"
            "0x2AA9" -> "CGM Status"
            "0x2AAA" -> "CGM Session Start Time"
            "0x2AAB" -> "CGM Session Run Time"
            "0x2AAC" -> "CGM Specific Ops Control Point"
            "0x2AAD" -> "Indoor Positioning Configuration"
            "0x2AAE" -> "Latitude"
            "0x2AAF" -> "Longitude"
            "0x2AB0" -> "Local North Coordinate"
            "0x2AB1" -> "Local East Coordinate"
            "0x2AB2" -> "Floor Number"
            "0x2AB3" -> "Altitude"
            "0x2AB4" -> "Uncertainty"
            "0x2AB5" -> "Location Name"
            "0x2AB6" -> "URI"
            "0x2AB7" -> "HTTP Headers"
            "0x2AB8" -> "HTTP Status Code"
            "0x2AB9" -> "HTTP Entity Body"
            "0x2ABA" -> "HTTP Control Point"
            "0x2ABB" -> "HTTPS Security"
            "0x2ABC" -> "TDS Control Point"
            "0x2ABD" -> "OTS Feature"
            "0x2ABE" -> "Object Name"
            "0x2ABF" -> "Object Type"
            "0x2AC0" -> "Object Size"
            "0x2AC1" -> "Object First -Created"
            "0x2AC2" -> "Object Last - Modified"
            "0x2AC3" -> "Object ID"
            "0x2AC4" -> "Object Properties"
            "0x2AC5" -> "Object Action Control Point"
            "0x2AC6" -> "Object List Control Point"
            "0x2AC7" -> "Object List Filter"
            "0x2AC8" -> "Object Changed"
            "0x2AC9" -> "Resolvable Private Address Only"
            "0x2ACC" -> "Fitness Machine Feature"
            "0x2ACD" -> "Treadmill Data"
            "0x2ACE" -> "Cross Trainer Data"
            "0x2ACF" -> "Step Climber Data"
            "0x2AD0" -> "Stair Climber Data"
            "0x2AD1" -> "Rower Data"
            "0x2AD2" -> "Indoor Bike Data"
            "0x2AD3" -> "Training Status"
            "0x2AD4" -> "Supported Speed Range"
            "0x2AD5" -> "Supported Inclination Range"
            "0x2AD6" -> "Supported Resistance Level Range"
            "0x2AD7" -> "Supported Heart Rate Range"
            "0x2AD8" -> "Supported Power Range"
            "0x2AD9" -> "Fitness Machine Control Point"
            "0x2ADA" -> "Fitness Machine Status"
            "0x2ADB" -> "Mesh Provisioning Data In"
            "0x2ADC" -> "Mesh Provisioning Data Out"
            "0x2ADD" -> "Mesh Proxy Data In"
            "0x2ADE" -> "Mesh Proxy Data Out"
            "0x2AE0" -> "Average Current"
            "0x2AE1" -> "Average Voltage"
            "0x2AE2" -> "Boolean"
            "0x2AE3" -> "Chromatic Distance from Planckian"
            "0x2AE4" -> "Chromaticity Coordinates"
            "0x2AE5" -> "Chromaticity in CCT and Duv Values"
            "0x2AE6" -> "Chromaticity Tolerance"
            "0x2AE7" -> "CIE 13.3 - 1995 Color Rendering Index"
            "0x2AE8" -> "Coefficient"
            "0x2AE9" -> "Correlated Color Temperature"
            "0x2AEA" -> "Count 16"
            "0x2AEB" -> "Count 24"
            "0x2AEC" -> "Country Code"
            "0x2AED" -> "Date UTC"
            "0x2AEE" -> "Electric Current"
            "0x2AEF" -> "Electric Current Range"
            "0x2AF0" -> "Electric Current Specification"
            "0x2AF1" -> "Electric Current Statistics"
            "0x2AF2" -> "Energy"
            "0x2AF3" -> "Energy in a Period of Day"
            "0x2AF4" -> "Event Statistics"
            "0x2AF5" -> "Fixed String 16"
            "0x2AF6" -> "Fixed String 24"
            "0x2AF7" -> "Fixed String 36"
            "0x2AF8" -> "Fixed String 8"
            "0x2AF9" -> "Generic Level"
            "0x2AFA" -> "Global Trade Item Number"
            "0x2AFB" -> "Illuminance"
            "0x2AFC" -> "Luminous Efficacy"
            "0x2AFD" -> "Luminous Energy"
            "0x2AFE" -> "Luminous Exposure"
            "0x2AFF" -> "Luminous Flux"
            "0x2B00" -> "Luminous Flux Range"
            "0x2B01" -> "Luminous Intensity"
            "0x2B02" -> "Mass Flow"
            "0x2B03" -> "Perceived Lightness"
            "0x2B04" -> "Percentage 8"
            "0x2B05" -> "Power"
            "0x2B06" -> "Power Specification"
            "0x2B07" -> "Relative Runtime in a Current Range"
            "0x2B08" -> "Relative Runtime in a Generic Level Range"
            "0x2B09" -> "Relative Value in a Voltage Range"
            "0x2B0A" -> "Relative Value in an Illuminance Range"
            "0x2B0B" -> "Relative Value in a Period of Day"
            "0x2B0C" -> "Relative Value in a Temperature Range"
            "0x2B0D" -> "Temperature 8"
            "0x2B0E" -> "Temperature 8 in a Period of Day"
            "0x2B0F" -> "Temperature 8 Statistics"
            "0x2B10" -> "Temperature Range"
            "0x2B11" -> "Temperature Statistics"
            "0x2B12" -> "Time Decihour 8"
            "0x2B13" -> "Time Exponential 8"
            "0x2B14" -> "Time Hour 24"
            "0x2B15" -> "Time Millisecond 24"
            "0x2B16" -> "Time Second 16"
            "0x2B17" -> "Time Second 8"
            "0x2B18" -> "Voltage"
            "0x2B19" -> "Voltage Specification"
            "0x2B1A" -> "Voltage Statistics"
            "0x2B1B" -> "Volume Flow"
            "0x2B1C" -> "Chromaticity Coordinate"
            "0x2B1D" -> "RC Feature"
            "0x2B1E" -> "RC Settings"
            "0x2B1F" -> "Reconnection Configuration Control Point"
            "0x2B20" -> "IDD Status Changed"
            "0x2B21" -> "IDD Status"
            "0x2B22" -> "IDD Annunciation Status"
            "0x2B23" -> "IDD Features"
            "0x2B24" -> "IDD Status Reader Control Point"
            "0x2B25" -> "IDD Command Control Point"
            "0x2B26" -> "IDD Command Data"
            "0x2B27" -> "IDD Record Access Control Point"
            "0x2B28" -> "IDD History Data"
            "0x2B29" -> "Client Supported Features"
            "0x2B2A" -> "Database Hash"
            "0x2B2B" -> "BSS Control Point"
            "0x2B2C" -> "BSS Response"
            "0x2B2D" -> "Emergency ID"
            "0x2B2E" -> "Emergency Text"
            "0x2B2F" -> "ACS Status"
            "0x2B30" -> "ACS Data In"
            "0x2B31" -> "ACS Data Out Notify"
            "0x2B32" -> "ACS Data Out Indicate"
            "0x2B33" -> "ACS Control Point"
            "0x2B34" -> "Enhanced Blood Pressure Measurement"
            "0x2B35" -> "Enhanced Intermediate Cuff Pressure"
            "0x2B36" -> "Blood Pressure Record"
            "0x2B37" -> "Registered User"
            "0x2B38" -> "BR - EDR Handover Data"
            "0x2B39" -> "Bluetooth SIG Data"
            "0x2B3A" -> "Server Supported Features"
            "0x2B3B" -> "Physical Activity Monitor Features"
            "0x2B3C" -> "General Activity Instantaneous Data"
            "0x2B3D" -> "General Activity Summary Data"
            "0x2B3E" -> "CardioRespiratory Activity Instantaneous Data"
            "0x2B3F" -> "CardioRespiratory Activity Summary Data"
            "0x2B40" -> "Step Counter Activity Summary Data"
            "0x2B41" -> "Sleep Activity Instantaneous Data"
            "0x2B42" -> "Sleep Activity Summary Data"
            "0x2B43" -> "Physical Activity Monitor Control Point"
            "0x2B44" -> "Activity Current Session"
            "0x2B45" -> "Physical Activity Session Descriptor"
            "0x2B46" -> "Preferred Units"
            "0x2B47" -> "High Resolution Height"
            "0x2B48" -> "Middle Name"
            "0x2B49" -> "Stride Length"
            "0x2B4A" -> "Handedness"
            "0x2B4B" -> "Device Wearing Position"
            "0x2B4C" -> "Four Zone Heart Rate Limits"
            "0x2B4D" -> "High Intensity Exercise Threshold"
            "0x2B4E" -> "Activity Goal"
            "0x2B4F" -> "Sedentary Interval Notification"
            "0x2B50" -> "Caloric Intake"
            "0x2B51" -> "TMAP Role"
            "0x2B77" -> "Audio Input State"
            "0x2B78" -> "Gain Settings Attribute"
            "0x2B79" -> "Audio Input Type"
            "0x2B7A" -> "Audio Input Status"
            "0x2B7B" -> "Audio Input Control Point"
            "0x2B7C" -> "Audio Input Description"
            "0x2B7D" -> "Volume State"
            "0x2B7E" -> "Volume Control Point"
            "0x2B7F" -> "Volume Flags"
            "0x2B80" -> "Volume Offset State"
            "0x2B81" -> "Audio Location"
            "0x2B82" -> "Volume Offset Control Point"
            "0x2B83" -> "Audio Output Description"
            "0x2B84" -> "Set Identity Resolving Key"
            "0x2B85" -> "Coordinated Set Size"
            "0x2B86" -> "Set Member Lock"
            "0x2B87" -> "Set Member Rank"
            "0x2B88" -> "Encrypted Data Key Material"
            "0x2B89" -> "Apparent Energy 32"
            "0x2B8A" -> "Apparent Power"
            "0x2B8B" -> "Live Health Observations"
            "0x2B8C" -> "CO \{} text-subscript { 2 } Concentration"
            "0x2B8D" -> "Cosine of the Angle"
            "0x2B8E" -> "Device Time Feature"
            "0x2B8F" -> "Device Time Parameters"
            "0x2B90" -> "Device Time"
            "0x2B91" -> "Device Time Control Point"
            "0x2B92" -> "Time Change Log Data"
            "0x2B93" -> "Media Player Name"
            "0x2B94" -> "Media Player Icon Object ID"
            "0x2B95" -> "Media Player Icon URL"
            "0x2B96" -> "Track Changed"
            "0x2B97" -> "Track Title"
            "0x2B98" -> "Track Duration"
            "0x2B99" -> "Track Position"
            "0x2B9A" -> "Playback Speed"
            "0x2B9B" -> "Seeking Speed"
            "0x2B9C" -> "Current Track Segments Object ID"
            "0x2B9D" -> "Current Track Object ID"
            "0x2B9E" -> "Next Track Object ID"
            "0x2B9F" -> "Parent Group Object ID"
            "0x2BA0" -> "Current Group Object ID"
            "0x2BA1" -> "Playing Order"
            "0x2BA2" -> "Playing Orders Supported"
            "0x2BA3" -> "Media State"
            "0x2BA4" -> "Media Control Point"
            "0x2BA5" -> "Media Control Point Opcodes Supported"
            "0x2BA6" -> "Search Results Object ID"
            "0x2BA7" -> "Search Control Point"
            "0x2BA8" -> "Energy 32"
            "0x2BA9" -> "Media Player Icon Object Type"
            "0x2BAA" -> "Track Segments Object Type"
            "0x2BAB" -> "Track Object Type"
            "0x2BAC" -> "Group Object Type"
            "0x2BAD" -> "Constant Tone Extension Enable"
            "0x2BAE" -> "Advertising Constant Tone Extension Minimum Length"
            "0x2BAF" -> "Advertising Constant Tone Extension Minimum Transmit Count"
            "0x2BB0" -> "Advertising Constant Tone Extension Transmit Duration"
            "0x2BB1" -> "Advertising Constant Tone Extension Interval"
            "0x2BB2" -> "Advertising Constant Tone Extension PHY"
            "0x2BB3" -> "Bearer Provider Name"
            "0x2BB4" -> "Bearer UCI"
            "0x2BB5" -> "Bearer Technology"
            "0x2BB6" -> "Bearer URI Schemes Supported List"
            "0x2BB7" -> "Bearer Signal Strength"
            "0x2BB8" -> "Bearer Signal Strength Reporting Interval"
            "0x2BB9" -> "Bearer List Current Calls"
            "0x2BBA" -> "Content Control ID"
            "0x2BBB" -> "Status Flags"
            "0x2BBC" -> "Incoming Call Target Bearer URI"
            "0x2BBD" -> "Call State"
            "0x2BBE" -> "Call Control Point"
            "0x2BBF" -> "Call Control Point Optional Opcodes"
            "0x2BC0" -> "Termination Reason"
            "0x2BC1" -> "Incoming Call"
            "0x2BC2" -> "Call Friendly Name"
            "0x2BC3" -> "Mute"
            "0x2BC4" -> "Sink ASE"
            "0x2BC5" -> "Source ASE"
            "0x2BC6" -> "ASE Control Point"
            "0x2BC7" -> "Broadcast Audio Scan Control Point"
            "0x2BC8" -> "Broadcast Receive State"
            "0x2BC9" -> "Sink PAC"
            "0x2BCA" -> "Sink Audio Locations"
            "0x2BCB" -> "Source PAC"
            "0x2BCC" -> "Source Audio Locations"
            "0x2BCD" -> "Available Audio Contexts"
            "0x2BCE" -> "Supported Audio Contexts"
            "0x2BCF" -> "Ammonia Concentration"
            "0x2BD0" -> "Carbon Monoxide Concentration"
            "0x2BD1" -> "Methane Concentration"
            "0x2BD2" -> "Nitrogen Dioxide Concentration"
            "0x2BD3" -> "Non -Methane Volatile Organic Compounds Concentration"
            "0x2BD4" -> "Ozone Concentration"
            "0x2BD5" -> "Particulate Matter - PM1 Concentration"
            "0x2BD6" -> "Particulate Matter - PM2.5 Concentration"
            "0x2BD7" -> "Particulate Matter - PM10 Concentration"
            "0x2BD8" -> "Sulfur Dioxide Concentration"
            "0x2BD9" -> "Sulfur Hexafluoride Concentration"
            "0x2BDA" -> "Hearing Aid Features"
            "0x2BDB" -> "Hearing Aid Preset Control Point"
            "0x2BDC" -> "Active Preset Index"
            "0x2BDD" -> "Stored Health Observations"
            "0x2BDE" -> "Fixed String 64"
            "0x2BDF" -> "High Temperature"
            "0x2BE0" -> "High Voltage"
            "0x2BE1" -> "Light Distribution"
            "0x2BE2" -> "Light Output"
            "0x2BE3" -> "Light Source Type"
            "0x2BE4" -> "Noise"
            "0x2BE5" -> "Relative Runtime in a Correlated Color Temperature Range"
            "0x2BE6" -> "Time Second 32"
            "0x2BE7" -> "VOC Concentration"
            "0x2BE8" -> "Voltage Frequency"
            "0x2BE9" -> "Battery Critical Status"
            "0x2BEA" -> "Battery Health Status"
            "0x2BEB" -> "Battery Health Information"
            "0x2BEC" -> "Battery Information"
            "0x2BED" -> "Battery Level Status"
            "0x2BEE" -> "Battery Time Status"
            "0x2BEF" -> "Estimated Service Date"
            "0x2BF0" -> "Battery Energy Status"
            "0x2BF1" -> "Observation Schedule Changed"
            "0x2BF2" -> "Current Elapsed Time"
            "0x2BF3" -> "Health Sensor Features"
            "0x2BF4" -> "GHS Control Point"
            "0x2BF5" -> "LE GATT Security Levels"
            "0x2BF6" -> "ESL Address"
            "0x2BF7" -> "AP Sync Key Material"
            "0x2BF8" -> "ESL Response Key Material"
            "0x2BF9" -> "ESL Current Absolute Time"
            "0x2BFA" -> "ESL Display Information"
            "0x2BFB" -> "ESL Image Information"
            "0x2BFC" -> "ESL Sensor Information"
            "0x2BFD" -> "ESL LED Information"
            "0x2BFE" -> "ESL Control Point"
            "0x2BFF" -> "UDI for Medical Devices"
            else -> "Unknown Characteristics"
        }

同修改一下原有的getServiceUUID()为getShortUUID()，只改名字而已，之前命名有点不太严谨。

四、特性适配器

首先我们在layout下创建一个item_characteristic.xml，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="wrap_content"
    android:layout_marginBottom="1dp"
    android:foreground="?attr/selectableItemBackground"
    android:paddingStart="16dp">

    <TextView
        android:id="@+id/tv_character_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="8dp"
        android:text="特性"
        android:textColor="@color/black"
        android:textSize="16sp"
        android:textStyle="bold"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/tv_uuid_title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="UUID："
        app:layout_constraintStart_toStartOf="@+id/tv_character_name"
        app:layout_constraintTop_toBottomOf="@+id/tv_character_name" />

    <TextView
        android:id="@+id/tv_character_uuid"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="UUID"
        android:textColor="@color/black"
        app:layout_constraintBottom_toBottomOf="@+id/tv_uuid_title"
        app:layout_constraintStart_toEndOf="@+id/tv_uuid_title"
        app:layout_constraintTop_toTopOf="@+id/tv_uuid_title" />

    <TextView
        android:id="@+id/tv_property_title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:text="Properties："
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="@+id/tv_character_name"
        app:layout_constraintTop_toBottomOf="@+id/tv_uuid_title" />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/rv_property"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_constraintBottom_toBottomOf="@+id/tv_property_title"
        app:layout_constraintStart_toEndOf="@+id/tv_property_title"
        app:layout_constraintTop_toTopOf="@+id/tv_property_title" />
        
</androidx.constraintlayout.widget.ConstraintLayout>

  这里显示特性的名称和UUIID，同时加载属性列表，然后写适配器，因为需要操作属性的缘故，这些写一个接口，在adapter包下新建一个OperateCallback接口，代码如下所示：

interface OperateCallback {
    /**
     * 属性操作
     */
    fun onPropertyOperate(characteristic: BluetoothGattCharacteristic, operateName: String)
}

通过这个接口可以知道当前操作的是那个特性和属性名称。下面我们写适配器，在adapter包下新建一个CharacteristicAdapter类，代码如下所示：

class CharacteristicAdapter(
    private val characteristics: List,
    private val callback: OperateCallback
) : RecyclerView.Adapter() {

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        return ViewHolder(ItemCharacteristicBinding.inflate(LayoutInflater.from(parent.context), parent, false))
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        holder.binding.tvCharacterName.text = BleUtils.getCharacteristicsName(characteristics[position].uuid)
        holder.binding.tvCharacterUuid.text = BleUtils.getShortUUID(characteristics[position].uuid)
        //加载特性下的属性
        holder.binding.rvProperty.apply {
            layoutManager = LinearLayoutManager(context).apply { orientation = LinearLayoutManager.HORIZONTAL }
            val properties: List = BleUtils.getProperties(characteristics[position].properties)
            adapter = PropertyAdapter(properties, object : OnItemClickListener {
                //点击属性
                override fun onItemClick(view: View?, position: Int) { callback.onPropertyOperate(characteristics[position], properties[position]) }
            })
        }
    }

    override fun getItemCount() = characteristics.size

    class ViewHolder(itemView: ItemCharacteristicBinding) : RecyclerView.ViewHolder(itemView.root) {
        var binding: ItemCharacteristicBinding

        init {
            binding = itemView
        }
    }
}

在这里我们就可以处理特性的名称和UUID显示，同时加载属性适配器，显示出来。

五、加载特性

  因为特性是在服务下的，所以我们可以在服务适配器中加载特性适配器。首先我们修改一下item_service.xml，代码如下所示：

<?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:orientation="vertical"
    android:background="@color/white"
    android:layout_height="wrap_content">

    <androidx.constraintlayout.widget.ConstraintLayout
        android:id="@+id/item_service"
        android:layout_width="match_parent"
        android:foreground="?attr/selectableItemBackground"
        android:layout_height="wrap_content"
        android:orientation="vertical">

        <TextView
            android:id="@+id/tv_service_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="16dp"
            android:layout_marginTop="8dp"
            android:text="服务"
            android:textColor="@color/black"
            android:textSize="16sp"
            android:textStyle="bold"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <TextView
            android:id="@+id/tv_uuid_title"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="UUID："
            app:layout_constraintStart_toStartOf="@+id/tv_service_name"
            app:layout_constraintTop_toBottomOf="@+id/tv_service_name" />

        <TextView
            android:id="@+id/tv_service_uuid"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="UUID"
            android:textColor="@color/black"
            app:layout_constraintBottom_toBottomOf="@+id/tv_uuid_title"
            app:layout_constraintStart_toEndOf="@+id/tv_uuid_title"
            app:layout_constraintTop_toTopOf="@+id/tv_uuid_title" />

        <TextView
            android:id="@+id/tv_service_info"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginBottom="8dp"
            android:text="PRIMARY SERVICE"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintStart_toStartOf="@+id/tv_service_name"
            app:layout_constraintTop_toBottomOf="@+id/tv_uuid_title" />

        <ImageView
            android:id="@+id/iv_state"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginEnd="16dp"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:srcCompat="@drawable/ic_right_24" />

    </androidx.constraintlayout.widget.ConstraintLayout>

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/rv_characteristics"
        android:visibility="gone"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingStart="16dp" />
</LinearLayout>

  整体上变化不大，只是加了一个RecyclerView，同时增加了一个ImageView，用于显示当前的服务是否展开，可以通过当前的服务item的方式控制是否显示特性列表，这里用到两个图标，在drawable下创建ic_right_24.xml，代码如下所示：

<vector xmlns:android="http://schemas.android.com/apk/res/android"
    android:width="24dp"
    android:height="24dp"
    android:tint="#000000"
    android:viewportWidth="24"
    android:viewportHeight="24">
    <path
        android:fillColor="@android:color/white"
        android:pathData="M10,17l5,-5 -5,-5v10z" />
</vector>

还有一个ic_down_24.xml

<vector xmlns:android="http://schemas.android.com/apk/res/android"
    android:width="24dp"
    android:height="24dp"
    android:tint="#000000"
    android:viewportWidth="24"
    android:viewportHeight="24">
    <path
        android:fillColor="@android:color/white"
        android:pathData="M7,10l5,5 5,-5z" />
</vector>

下面修改一下ServiceAdapter，代码如下所示：

class ServiceAdapter(
    private val services: List,
    private val callback: OperateCallback
) : RecyclerView.Adapter() {

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        val viewHolder = ViewHolder(ItemServiceBinding.inflate(LayoutInflater.from(parent.context), parent, false))
        viewHolder.binding.itemService.setOnClickListener {
            //显示特性列表
            viewHolder.binding.rvCharacteristics.visibility = if (viewHolder.binding.rvCharacteristics.visibility == View.VISIBLE) View.GONE else View.VISIBLE
            //更换图标
            viewHolder.binding.ivState.setImageDrawable(
                if (viewHolder.binding.rvCharacteristics.visibility == View.VISIBLE) ContextCompat.getDrawable(parent.context, R.drawable.ic_down_24)
                else ContextCompat.getDrawable(parent.context, R.drawable.ic_right_24)
            )
        }
        return viewHolder
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        holder.binding.tvServiceName.text = BleUtils.getServiceName(services[position].uuid)
        holder.binding.tvServiceUuid.text = BleUtils.getShortUUID(services[position].uuid)
        //加载服务下的特性
        holder.binding.rvCharacteristics.apply {
            layoutManager = LinearLayoutManager(context)
            adapter = CharacteristicAdapter(services[position].characteristics, callback)
        }
    }

    override fun getItemCount() = services.size

    class ViewHolder(itemView: ItemServiceBinding) : RecyclerView.ViewHolder(itemView.root) {
        var binding: ItemServiceBinding

        init {
            binding = itemView
        }
    }
}

  和之前的区别就在于构造的时候增加了一个回调，并且在onCreateViewHolder()函数中就处理了服务Item的点击事件，而不是像之前一样回调到Activity中，在服务Item的点击事件中判断是否显示特性列表同时修改图标资源。最后再将接口回调到Activity中。

六、显示特性和属性

  现在要做的就是修改MainActivity中的代码，首先修改activity_main.xml中的代码，主要是修改之前的rv_service中的属性值，修改后如下所示：

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/rv_service"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/tv_device_info" />

主要就是让RecyclerView占满剩下的空间，避免内容过多导致无法滑动的情况，最后我们修改一下MainActivity中代码，如下所示：

class MainActivity : BaseActivity(), BleCallback, OperateCallback {

    ...

    override fun onServicesDiscovered(services: List) {
        runOnUiThread {
            mServiceList.clear()
            mServiceList.addAll(services)
            mServiceAdapter ?: run {
                mServiceAdapter = ServiceAdapter(mServiceList, this@MainActivity)
                binding.rvService.apply {
                    (itemAnimator as SimpleItemAnimator).supportsChangeAnimations = false
                    layoutManager = LinearLayoutManager(this@MainActivity)
                    adapter = mServiceAdapter
                    //增加分隔线
                    addItemDecoration(DividerItemDecoration(this@MainActivity, DividerItemDecoration.VERTICAL))
                }
                mServiceAdapter
            }
            mServiceAdapter!!.notifyDataSetChanged()
        }
    }

    /**
     * 属性操作
     */
    override fun onPropertyOperate(characteristic: BluetoothGattCharacteristic, operateName: String) {
        showMsg(operateName)
    }
}

  修改的地方有三个，第一个就是MainActivity实现OnItemClickListener改成OperateCallback ，第二个是onServicesDiscovered()函数中，构建ServiceAdapter适配器中实现接口，然后添加分隔线，最后一个就是去掉之前onItemClick()函数改成onPropertyOperate()函数，运行一下看看效果。

文章来源于互联网:Android Ble蓝牙App（三）特性和属性