【HarmonyOS 5】鴻蒙星閃NearLink詳解

一、前言

鴻蒙星閃NearLink Kit 是 HarmonyOS 提供的短距離通信服務，支持星閃設備間的連接、數據交互。例如，手機可作為中心設備與外圍設備（如鼠標、手寫筆、智能家電、車鑰匙等）通過星閃進行連接。

二、NearLink Kit 的接入與使用：

點擊跳轉官方文檔地址

鴻蒙星閃（NearLink）的基本接入代碼示例，包含設備發現、連接和數據傳輸的核心流程：

// NearLink設備管理服務示例

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

// 星閃服務管理類
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;
  }
  
  // 初始化星閃服務
  async initNearLinkService() {
    try {
      // 檢查並請求星閃權限
      await this.checkAndRequestNearLinkPermission();
      
      // 創建設備管理器實例
      this.deviceManager = await nearlinkSle.getSleDeviceManager(this.context!);
      
      // 註冊設備狀態變化監聽
      this.registerDeviceStateListener();
      
      console.info('NearLink service initialized successfully');
    } catch (error) {
      console.error(`Failed to initialize NearLink service: ${error}`);
      throw error;
    }
  }
  
  // 檢查並請求星閃權限
  private async checkAndRequestNearLinkPermission() {
    // 權限檢查邏輯
    // ...
  }
  
  // 開始掃描附近的星閃設備
  async startDiscovery() {
    if (!this.deviceManager) {
      throw new Error('Device manager not initialized');
    }
    
    try {
      // 配置掃描參數
      const discoveryConfig = {
        mode: nearlinkSle.SleDiscoveryMode.ACTIVE,
        duration: 30, // 掃描持續時間(秒)
        filter: {
          deviceTypes: [nearlinkSle.SleDeviceType.ALL]
        }
      };
      
      // 註冊設備發現回調
      const callback = {
        onDeviceFound: (device: nearlinkSle.SleDevice) => {
          console.info(`Found device: ${device.deviceName}, type: ${device.deviceType}`);
          // 處理髮現的設備，例如更新UI
          this.onDeviceDiscovered(device);
        },
        onDiscoveryStateChanged: (state: number) => {
          console.info(`Discovery state changed: ${state}`);
        }
      };
      
      // 開始掃描
      await this.deviceManager.startDiscovery(discoveryConfig, callback);
      console.info('NearLink device discovery started');
    } catch (error) {
      console.error(`Failed to start discovery: ${error}`);
      throw error;
    }
  }
  
  // 處理髮現的設備
  private onDeviceDiscovered(device: nearlinkSle.SleDevice) {
    // 這裏可以添加設備過濾邏輯
    // ...
    
    // 通知UI更新設備列表
    // ...
  }
  
  // 連接到指定星閃設備
  async connectToDevice(deviceId: string) {
    if (!this.deviceManager) {
      throw new Error('Device manager not initialized');
    }
    
    try {
      // 創建連接參數
      const connectParams = {
        timeout: 10000, // 連接超時時間(毫秒)
        connectionType: nearlinkSle.SleConnectionType.DATA_CHANNEL
      };
      
      // 連接設備
      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}`);
        
        // 註冊數據接收回調
        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;
    }
  }
  
  // 註冊數據接收監聽器
  private registerDataReceiveListener() {
    if (!this.dataChannel) return;
    
    this.dataChannel.on('dataReceived', (data: ArrayBuffer) => {
      // 處理接收到的數據
      const decoder = new TextDecoder();
      const message = decoder.decode(data);
      console.info(`Received data: ${message}`);
      
      // 通知UI有新數據到達
      // ...
    });
  }
  
  // 發送數據到已連接設備
  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;
      
      // 發送數據
      await this.dataChannel.send(data);
      console.info(`Data sent successfully: ${message}`);
    } catch (error) {
      console.error(`Failed to send data: ${error}`);
      throw error;
    }
  }
  
  // 斷開與設備的連接
  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;
    }
  }
  
  // 註冊設備狀態變化監聽
  private registerDeviceStateListener() {
    if (!this.deviceManager) return;
    
    this.deviceManager.on('deviceStateChanged', (params) => {
      console.info(`Device state changed: ${JSON.stringify(params)}`);
      // 處理設備狀態變化
      // ...
    });
  }
  
  // 釋放資源
  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、鴻蒙星閃指標對比

以下是鴻蒙星閃、藍牙和NFC在技術性能、應用場景、成本與生態系統等方面的區別表格：