Harmony Ble蓝牙App(四)描述符

Harmony Ble蓝牙App(四)描述符

  • 前言
  • 正文
    • 一、优化
    • 二、描述
      • ① 概念
      • ② 描述提供者
      • ③ 显示描述符
    • 三、源码

前言

  上一篇中了解了特性和属性,同时显示设备蓝牙服务下的特性和属性,本文中就需要来使用这些特性和属性来完成一些功能。

正文

  上一篇完成了特性,这一篇中我们增加描述符的处理,以及一些简单的优化。

一、优化

  这样看起来主页面在没有设备信息的时候不会显得单调,那么还有一个小细节就是,当设备的蓝牙服务和特性不属于SIG定义的,是厂商自定义时,我们最好就显示完整的UUID,为了方便使用,在BleUtils类中增加如下代码:

	public static final String APP_NAME = "GoodBle";

    public static final String UNKNOWN_DEVICE = "Unknown device";

    public static final String UNKNOWN_SERVICE = "Unknown Service";

    public static final String UNKNOWN_CHARACTERISTICS = "Unknown Characteristics";

    public static final String UNKNOWN_DESCRIPTOR = "Unknown Descriptor";

    public static final String BROADCAST = "Broadcast";

    public static final String READ = "Read";

    public static final String WRITE_NO_RESPONSE = "Write No Response";

    public static final String WRITE = "Write";

    public static final String NOTIFY = "Notify";

    public static final String INDICATE = "Indicate";

    public static final String AUTHENTICATED_SIGNED_WRITES = "Authenticated Signed Writes";

    public static final String EXTENDED_PROPERTIES = "Extended Properties";

  这里定义了一些常量,包括未知服务、未知特性,和一些其他的属性,这样做在修改的时候修改一个常量就可以了。下面我们分别修改一下BleUtils中的getServiceName()getCharacteristicsName()方法的else的值为UNKNOWN_SERVICEUNKNOWN_CHARACTERISTICS,剩下的就可以在服务适配器和特性适配器中去修改了,首先是服务适配器,修改

    @Override
    public Component getComponent(int position, Component component, ComponentContainer componentContainer) {
        ...

        String serviceName = BleUtils.getServiceName(service.getUuid());
        holder.txServiceName.setText(serviceName);
        holder.txUuid.setText(serviceName.equals(BleUtils.UNKNOWN_SERVICE) ? service.getUuid().toString() : BleUtils.getShortUUID(service.getUuid()));
        return cpt;
    }

在设置uuid的时候根据服务的名称进行判断,如果是标准的SIG服务则使用短UUID,不是则使用完整的UUID。默认是小写的,你也可以改成大写。

那么同样特性适配器也改一下:

    @Override
    public Component getComponent(int position, Component component, ComponentContainer componentContainer) {
        ...

        String characteristicsName = BleUtils.getCharacteristicsName(characteristic.getUuid());
        holder.txCharacterName.setText(characteristicsName);
        holder.txUuid.setText(BleUtils.getShortUUID(characteristic.getUuid()));
        holder.txUuid.setText(characteristicsName.equals(BleUtils.UNKNOWN_CHARACTERISTICS) ? characteristic.getUuid().toString() : BleUtils.getShortUUID(characteristic.getUuid()));
        return cpt;
    }

再运行一下,对于未知设备服务和特性的UUID就会显示完整的值。

二、描述

  在上一篇中提到了特性和属性,特性有那些功能是属性决定的,那么描述又是做什么的呢?

① 概念

在蓝牙低功耗(BLE)中,Descriptor(描述符)是用于提供有关特征值的额外信息的数据结构。Descriptor 提供了特定特征的更详细描述和配置选项。Descriptor 是特征(Characteristics)的子项,用于描述特征的特定属性或行为。每个特征可以有一个或多个 Descriptor。

以下是一些常见的 BLE Descriptor 类型及其含义:

  1. 声明 Descriptor:这个 Descriptor 用于描述特征的声明信息,包括特征的唯一标识符、权限、值的格式和其他标志。它提供了特征的基本信息供其他设备了解。

  2. 用户描述(User Description)Descriptor:用于提供特征的人类可读描述信息。这个描述可以是特征的名称、标签或其他有关特征的说明性文字。

  3. 配置 Descriptor:用于描述特征的配置选项。这个 Descriptor 可以包含特征的可选设置,例如采样率、测量单位或阈值等。

  4. 通知 Descriptor:用于配置特征是否支持通知功能。这个 Descriptor 可以用于使设备可以接收特征值变化的通知。

  5. 线性区间 Descriptor:用于描述特征值的线性关系,例如数值范围和步长等。

  6. 客户端配置 Descriptor:用于允许远程设备(例如中心设备)订阅特征值的变化通知,这个很重要。
    这些只是一些常见的 BLE Descriptor 类型和其含义的示例,实际上可以根据应用需求定义自定义的 Descriptor。

    Descriptor 提供了对特征更详细的描述和配置,它们可以通过蓝牙协议进行传输和访问。在 BLE 应用中,Descriptor 充当了配置和元数据信息的重要角色,帮助设备之间准确地交换和理解数据。

那么现在你已经了解了描述符的作用了,而我们目前的特性下还没有描述符的,注意不是每一个特性都有描述符,下面我们就来把描述符写出来了。首先我们在item_characteristic.xml中增加一个描述的列表控件,代码如下所示:


<DependentLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:height="match_content"
    ohos:width="match_parent"
    ohos:background_element="#FFFFFF"
    ohos:bottom_margin="2vp"
    ohos:bottom_padding="8vp"
    ohos:end_padding="16vp"
    ohos:start_padding="16vp"
    ohos:top_padding="8vp">

    <Text
        ohos:id="$+id:tx_character_name"
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:background_element="$color:black"
        ohos:text="服务"
        ohos:text_size="16fp"/>

    <Text
        ohos:id="$+id:tx_uuid_title"
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:below="$id:tx_character_name"
        ohos:text="UUID:"
        ohos:text_color="$color:gray"
        ohos:text_size="16fp"
        ohos:top_margin="2vp"/>

    <Text
        ohos:id="$+id:tx_uuid"
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:background_element="$color:black"
        ohos:below="$id:tx_character_name"
        ohos:end_of="$id:tx_uuid_title"
        ohos:text="UUID"
        ohos:text_size="16fp"
        ohos:top_margin="2vp"/>

    <Text
        ohos:id="$+id:tx_property_title"
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:below="$id:tx_uuid_title"
        ohos:text="Properties:"
        ohos:text_color="$color:gray"
        ohos:text_size="16fp"
        ohos:top_margin="2vp"/>

    <ListContainer
        ohos:id="$+id:lc_property"
        ohos:height="match_content"
        ohos:width="match_parent"
        ohos:align_bottom="$id:tx_property_title"
        ohos:align_top="$id:tx_property_title"
        ohos:end_of="$id:tx_property_title"
        ohos:orientation="horizontal"/>

    <DirectionalLayout
        ohos:id="$+id:lay_descriptors"
        ohos:height="match_content"
        ohos:width="match_parent"
        ohos:below="$id:tx_property_title"
        ohos:orientation="vertical">

        <Text
            ohos:height="match_content"
            ohos:width="match_content"
            ohos:text="Descriptors:"
            ohos:text_color="#000000"
            ohos:text_size="16fp"
            ohos:top_margin="2vp"/>

        <ListContainer
            ohos:id="$+id:lc_descriptor"
            ohos:height="match_content"
            ohos:width="match_parent"/>

    DirectionalLayout>

DependentLayout>

下面我们就可以正式去写描述符的提供者了。

② 描述提供者

  首先在layout下增加一个item_descriptor.xml,代码如下所示:


<DependentLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:height="match_content"
    ohos:width="match_parent"
    ohos:background_element="#FFFFFF"
    ohos:bottom_margin="2vp"
    ohos:bottom_padding="4vp"
    ohos:top_padding="4vp">

    <Text
        ohos:id="$+id:tx_descriptor_name"
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:background_element="$color:black"
        ohos:text="描述"
        ohos:text_size="16fp"/>

    <Text
        ohos:id="$+id:tx_uuid_title"
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:below="$id:tx_descriptor_name"
        ohos:text="UUID:"
        ohos:text_color="$color:gray"
        ohos:text_size="16fp"
        ohos:top_margin="2vp"/>

    <Text
        ohos:id="$+id:tx_uuid"
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:background_element="$color:black"
        ohos:below="$id:tx_descriptor_name"
        ohos:end_of="$id:tx_uuid_title"
        ohos:text="UUID"
        ohos:text_size="16fp"
        ohos:top_margin="2vp"/>

DependentLayout>

然后关于描述符的名称,我们可以在BleUtils中写一个函数,代码如下所示:

    public static String getDescriptorName(UUID uuid) {
        String targetUuid = getShortUUID(uuid);
        switch (targetUuid) {
            case "0x2900":
                return "Characteristic Extended Properties";
            case "0x2901":
                return "Characteristic User Description";
            case "0x2902":
                return "Client Characteristic Configuration";
            case "0x2903":
                return "Server Characteristic Configuration";
            case "0x2904":
                return "Characteristic Presentation Format";
            case "0x2905":
                return "Characteristic Aggregate Format";
            case "0x2906":
                return "Valid Range";
            case "0x2907":
                return "External Report Reference";
            case "0x2908":
                return "Report Reference";
            case "0x2909":
                return "Number of Digitals";
            case "0x290A":
                return "Value Trigger Setting";
            case "0x290B":
                return "Environmental Sensing Configuration";
            case "0x290C":
                return "Environmental Sensing Measurement";
            case "0x290D":
                return "Environmental Sensing Trigger Setting";
            case "0x290E":
                return "Time Trigger Setting";
            case "0x290F":
                return "Complete BR-EDR Transport Block Data";
            case "0x2910":
                return "Observation Schedule";
            case "0x2911":
                return "Valid Range and Accuracy";
            default:
                return UNKNOWN_DESCRIPTOR;
        }
    }

  下面我们写描述符适配器,在provider包下新建一个DescriptorProvider类,代码如下所示:

public class DescriptorProvider extends BaseItemProvider {

    private final List<GattDescriptor> descriptorList;
    private final AbilitySlice slice;

    public DescriptorProvider(List<GattDescriptor> list, AbilitySlice slice) {
        this.descriptorList = list;
        this.slice = slice;
    }

    @Override
    public int getCount() {
        return descriptorList == null ? 0 : descriptorList.size();
    }

    @Override
    public Object getItem(int position) {
        if (descriptorList != null && position >= 0 && position < descriptorList.size()) {
            return descriptorList.get(position);
        }
        return null;
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public Component getComponent(int position, Component component, ComponentContainer componentContainer) {
        final Component cpt;
        DescriptorHolder holder;

        GattDescriptor descriptor = descriptorList.get(position);
        if (component == null) {
            cpt = LayoutScatter.getInstance(slice).parse(ResourceTable.Layout_item_descriptor, null, false);
            holder = new DescriptorHolder(cpt);
            //将获取到的子组件信息绑定到列表项的实例中
            cpt.setTag(holder);
        } else {
            cpt = component;
            // 从缓存中获取到列表项实例后,直接使用绑定的子组件信息进行数据填充。
            holder = (DescriptorHolder) cpt.getTag();
        }

        String descriptorName = BleUtils.getDescriptorName(descriptor.getUuid());
        holder.txDescriptorName.setText(descriptorName);
        holder.txUuid.setText(descriptorName.equals(BleUtils.UNKNOWN_DESCRIPTOR) ? descriptor.getUuid().toString() : BleUtils.getShortUUID(descriptor.getUuid()));
        return cpt;
    }

    /**
     * 用于保存列表项的子组件信息
     */
    public static class DescriptorHolder {
        Text txDescriptorName;
        Text txUuid;
        ListContainer lcProperty;

        public DescriptorHolder(Component component) {
            txDescriptorName = (Text) component.findComponentById(ResourceTable.Id_tx_descriptor_name);
            txUuid = (Text) component.findComponentById(ResourceTable.Id_tx_uuid);
            lcProperty = (ListContainer) component.findComponentById(ResourceTable.Id_lc_property);
        }
    }
}

可以看这里的代码同样对于自定义UUID展示完整数据,对于SIG的展示短UUID。

③ 显示描述符

  接下来就是在特性适配器中去加载显示描述符数据,修改CharacteristicProvider中代码,所示代码:

public class CharacteristicProvider extends BaseItemProvider {

    private final List<GattCharacteristic> characteristicList;
    private final AbilitySlice slice;
    private final OperateCallback operateCallback;

    public CharacteristicProvider(List<GattCharacteristic> list, AbilitySlice slice, OperateCallback operateCallback) {
        this.characteristicList = list;
        this.slice = slice;
        this.operateCallback = operateCallback;
    }

    @Override
    public int getCount() {
        return characteristicList == null ? 0 : characteristicList.size();
    }

    @Override
    public Object getItem(int position) {
        if (characteristicList != null && position >= 0 && position < characteristicList.size()) {
            return characteristicList.get(position);
        }
        return null;
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public Component getComponent(int position, Component component, ComponentContainer componentContainer) {
        final Component cpt;
        CharacteristicHolder holder;

        GattCharacteristic characteristic = characteristicList.get(position);
        if (component == null) {
            cpt = LayoutScatter.getInstance(slice).parse(ResourceTable.Layout_item_characteristic, null, false);
            holder = new CharacteristicHolder(cpt);
            //将获取到的子组件信息绑定到列表项的实例中
            cpt.setTag(holder);
        } else {
            cpt = component;
            // 从缓存中获取到列表项实例后,直接使用绑定的子组件信息进行数据填充。
            holder = (CharacteristicHolder) cpt.getTag();
        }

        String characteristicsName = BleUtils.getCharacteristicsName(characteristic.getUuid());
        holder.txCharacterName.setText(characteristicsName);
        holder.txUuid.setText(BleUtils.getShortUUID(characteristic.getUuid()));
        holder.txUuid.setText(characteristicsName.equals(BleUtils.UNKNOWN_CHARACTERISTICS) ? characteristic.getUuid().toString() : BleUtils.getShortUUID(characteristic.getUuid()));

        List<String> properties = BleUtils.getProperties(characteristic.getProperties());
        //加载属性
        holder.lcProperty.setItemProvider(new PropertyProvider(properties, slice));
        //属性列表点击
        holder.lcProperty.setItemClickedListener((listContainer, component1, propertyPosition, l) -> {
            if (operateCallback != null) {
                //属性操作回调
                operateCallback.onPropertyOperate(characteristic, properties.get(propertyPosition));
            }
        });
        //加载特性下的描述
        if (characteristic.getDescriptors().size() > 0) {
            holder.lcDescriptor.setItemProvider(new DescriptorProvider(characteristic.getDescriptors(), slice));
        } else {
            holder.layDescriptor.setVisibility(Component.HIDE);
        }

        return cpt;
    }

    /**
     * 用于保存列表项的子组件信息
     */
    public static class CharacteristicHolder {
        Text txCharacterName;
        Text txUuid;
        ListContainer lcProperty;
        DirectionalLayout layDescriptor;
        ListContainer lcDescriptor;

        public CharacteristicHolder(Component component) {
            txCharacterName = (Text) component.findComponentById(ResourceTable.Id_tx_character_name);
            txUuid = (Text) component.findComponentById(ResourceTable.Id_tx_uuid);
            lcProperty = (ListContainer) component.findComponentById(ResourceTable.Id_lc_property);
            layDescriptor = (DirectionalLayout) component.findComponentById(ResourceTable.Id_lay_descriptors);
            lcDescriptor = (ListContainer) component.findComponentById(ResourceTable.Id_lc_descriptor);
        }
    }
}

请注意这一段代码:

        //加载特性下的描述
        if (characteristic.getDescriptors().size() > 0) {
            holder.lcDescriptor.setItemProvider(new DescriptorProvider(characteristic.getDescriptors(), slice));
        } else {
            holder.layDescriptor.setVisibility(Component.HIDE);
        }

  这个判断和重要,因为不是每一个特性都有描述符,这个前面已经说过了,没有的我们就直接隐藏对应的描述符布局,否则就加载描述符数据,同时我们还需要修改一下服务UUID和特性UUID的Text控件的属性,因为UUID过长的话可能一行无法显示出来。

改动如下:

服务uuid:

        <Text
            ohos:id="$+id:tx_uuid"
            ohos:height="match_content"
            ohos:width="match_content"
            ohos:background_element="$color:black"
            ohos:below="$id:tx_service_name"
            ohos:truncation_mode="ellipsis_at_middle"
            ohos:end_margin="24vp"
            ohos:text="UUID"
            ohos:end_of="$id:tx_uuid_title"
            ohos:align_end="$id:iv_state"
            ohos:text_size="16fp"
            ohos:top_margin="2vp"/>

特性uuid:

    <Text
        ohos:id="$+id:tx_uuid"
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:background_element="$color:black"
        ohos:below="$id:tx_character_name"
        ohos:end_of="$id:tx_uuid_title"
        ohos:truncation_mode="ellipsis_at_middle"
        ohos:text="UUID"
        ohos:text_size="16fp"
        ohos:top_margin="2vp"/>

下面运行看一下。

Harmony Ble蓝牙App(四)描述符_第1张图片

通过这个图就可以清晰的的看到特性下的描述符,本文就到这里了。

三、源码

如果对你有所帮助的话,不妨 StarFork,山高水长,后会有期~

源码地址:HarmonyBle-Java

你可能感兴趣的:(蓝牙,鸿蒙,java,鸿蒙,BLE蓝牙)