【HarmonyOS 5】鸿蒙星闪NearLink详解

一、前言

鸿蒙星闪NearLink Kit 是 HarmonyOS 提供的短距离通信服务，支持星闪设备间的连接、数据交互。例如，手机可作为中心设备与外围设备（如鼠标、手写笔、智能家电、车钥匙等）通过星闪进行连接。

二、NearLink Kit 的接入与使用：

点击跳转官方文档地址

鸿蒙星闪（NearLink）的基本接入代码示例，包含设备发现、连接和数据传输的核心流程：

// NearLink设备管理服务示例

import nearlink from '@ohos.nearlink';
import nearlinkSle from '@ohos.nearlink.sle';
import common from '@ohos.app.ability.common';

// 星闪服务管理类
export class NearLinkManager {
  private context: common.UIAbilityContext | undefined;
  private deviceManager: nearlinkSle.SleDeviceManager | undefined;
  private connectedDeviceId: string | null = null;
  private dataChannel: nearlinkSle.SleDataChannel | undefined;
  
  constructor(context: common.UIAbilityContext) {
    this.context = context;
  }
  
  // 初始化星闪服务
  async initNearLinkService() {
    try {
      // 检查并请求星闪权限
      await this.checkAndRequestNearLinkPermission();
      
      // 创建设备管理器实例
      this.deviceManager = await nearlinkSle.getSleDeviceManager(this.context!);
      
      // 注册设备状态变化监听
      this.registerDeviceStateListener();
      
      console.info('NearLink service initialized successfully');
    } catch (error) {
      console.error(`Failed to initialize NearLink service: ${error}`);
      throw error;
    }
  }
  
  // 检查并请求星闪权限
  private async checkAndRequestNearLinkPermission() {
    // 权限检查逻辑
    // ...
  }
  
  // 开始扫描附近的星闪设备
  async startDiscovery() {
    if (!this.deviceManager) {
      throw new Error('Device manager not initialized');
    }
    
    try {
      // 配置扫描参数
      const discoveryConfig = {
        mode: nearlinkSle.SleDiscoveryMode.ACTIVE,
        duration: 30, // 扫描持续时间(秒)
        filter: {
          deviceTypes: [nearlinkSle.SleDeviceType.ALL]
        }
      };
      
      // 注册设备发现回调
      const callback = {
        onDeviceFound: (device: nearlinkSle.SleDevice) => {
          console.info(`Found device: ${device.deviceName}, type: ${device.deviceType}`);
          // 处理发现的设备，例如更新UI
          this.onDeviceDiscovered(device);
        },
        onDiscoveryStateChanged: (state: number) => {
          console.info(`Discovery state changed: ${state}`);
        }
      };
      
      // 开始扫描
      await this.deviceManager.startDiscovery(discoveryConfig, callback);
      console.info('NearLink device discovery started');
    } catch (error) {
      console.error(`Failed to start discovery: ${error}`);
      throw error;
    }
  }
  
  // 处理发现的设备
  private onDeviceDiscovered(device: nearlinkSle.SleDevice) {
    // 这里可以添加设备过滤逻辑
    // ...
    
    // 通知UI更新设备列表
    // ...
  }
  
  // 连接到指定星闪设备
  async connectToDevice(deviceId: string) {
    if (!this.deviceManager) {
      throw new Error('Device manager not initialized');
    }
    
    try {
      // 创建连接参数
      const connectParams = {
        timeout: 10000, // 连接超时时间(毫秒)
        connectionType: nearlinkSle.SleConnectionType.DATA_CHANNEL
      };
      
      // 连接设备
      const connectionResult = await this.deviceManager.connect(deviceId, connectParams);
      if (connectionResult.resultCode === 0) {
        this.connectedDeviceId = deviceId;
        this.dataChannel = connectionResult.dataChannel;
        console.info(`Connected to device: ${deviceId}`);
        
        // 注册数据接收回调
        this.registerDataReceiveListener();
      } else {
        console.error(`Failed to connect device, error code: ${connectionResult.resultCode}`);
        throw new Error(`Connection failed: ${connectionResult.resultCode}`);
      }
    } catch (error) {
      console.error(`Failed to connect device: ${error}`);
      throw error;
    }
  }
  
  // 注册数据接收监听器
  private registerDataReceiveListener() {
    if (!this.dataChannel) return;
    
    this.dataChannel.on('dataReceived', (data: ArrayBuffer) => {
      // 处理接收到的数据
      const decoder = new TextDecoder();
      const message = decoder.decode(data);
      console.info(`Received data: ${message}`);
      
      // 通知UI有新数据到达
      // ...
    });
  }
  
  // 发送数据到已连接设备
  async sendData(message: string) {
    if (!this.dataChannel) {
      throw new Error('Data channel not initialized');
    }
    
    try {
      const encoder = new TextEncoder();
      const data = encoder.encode(message).buffer;
      
      // 发送数据
      await this.dataChannel.send(data);
      console.info(`Data sent successfully: ${message}`);
    } catch (error) {
      console.error(`Failed to send data: ${error}`);
      throw error;
    }
  }
  
  // 断开与设备的连接
  async disconnect() {
    if (!this.deviceManager || !this.connectedDeviceId) return;
    
    try {
      await this.deviceManager.disconnect(this.connectedDeviceId);
      this.connectedDeviceId = null;
      this.dataChannel = undefined;
      console.info('Device disconnected');
    } catch (error) {
      console.error(`Failed to disconnect device: ${error}`);
      throw error;
    }
  }
  
  // 注册设备状态变化监听
  private registerDeviceStateListener() {
    if (!this.deviceManager) return;
    
    this.deviceManager.on('deviceStateChanged', (params) => {
      console.info(`Device state changed: ${JSON.stringify(params)}`);
      // 处理设备状态变化
      // ...
    });
  }
  
  // 释放资源
  async release() {
    await this.disconnect();
    
    if (this.deviceManager) {
      try {
        await this.deviceManager.release();
        console.info('NearLink resources released');
      } catch (error) {
        console.error(`Failed to release resources: ${error}`);
      }
    }
  }
}

三、鸿蒙星闪指标对比

以下是鸿蒙星闪、蓝牙和NFC在技术性能、应用场景、成本与生态系统等方面的区别表格：