AVplayer开发音频播放功能

import media from '@ohos.multimedia.media'; 
import fs from '@ohos.file.fs'; 
import common from '@ohos.app.ability.common'; 
import { BusinessError } from '@ohos.base'; 
  
export class AVPlayerDemo { 
  private count: number = 0; 
  private isSeek: boolean = true; // 用于区分模式是否支持seek操作 
  private fileSize: number = -1; 
  private fd: number = 0; 
  // 注册avplayer回调函数 
  setAVPlayerCallback(avPlayer: media.AVPlayer) { 
    // seek操作结果回调函数 
    avPlayer.on('seekDone', (seekDoneTime: number) => { 
      console.info(`AVPlayer seek succeeded, seek time is ${seekDoneTime}`); 
    }) 
    // error回调监听函数,当avPlayer在操作过程中出现错误时调用 reset接口触发重置流程 
    avPlayer.on('error', (err: BusinessError) => { 
      console.error(`Invoke avPlayer failed, code is ${err.code}, message is ${err.message}`); 
      avPlayer.reset(); // 调用reset重置资源，触发idle状态 
    }) 
    // 状态机变化回调函数 
    avPlayer.on('stateChange', async (state: string, reason: media.StateChangeReason) => { 
      switch (state) { 
        case 'idle': // 成功调用reset接口后触发该状态机上报 
          console.info('AVPlayer state idle called.'); 
          avPlayer.release(); // 调用release接口销毁实例对象 
          break; 
        case 'initialized': // avplayer 设置播放源后触发该状态上报 
          console.info('AVPlayer state initialized called.'); 
          avPlayer.prepare(); 
          break; 
        case 'prepared': // prepare调用成功后上报该状态机 
          console.info('AVPlayer state prepared called.'); 
          avPlayer.play(); // 调用播放接口开始播放 
          break; 
        case 'playing': // play成功调用后触发该状态机上报 
          console.info('AVPlayer state playing called.'); 
          if (this.count !== 0) { 
            if (this.isSeek) { 
              console.info('AVPlayer start to seek.'); 
              avPlayer.seek(avPlayer.duration); //seek到音频末尾 
            } else { 
              // 当播放模式不支持seek操作时继续播放到结尾 
              console.info('AVPlayer wait to play end.'); 
            } 
          } else { 
            avPlayer.pause(); // 调用暂停接口暂停播放 
          } 
          this.count++; 
          break; 
        case 'paused': // pause成功调用后触发该状态机上报 
          console.info('AVPlayer state paused called.'); 
          avPlayer.play(); // 再次播放接口开始播放 
          break; 
        case 'completed': // 播放结束后触发该状态机上报 
          console.info('AVPlayer state completed called.'); 
          avPlayer.stop(); //调用播放结束接口 
          break; 
        case 'stopped': // stop接口成功调用后触发该状态机上报 
          console.info('AVPlayer state stopped called.'); 
          avPlayer.reset(); // 调用reset接口初始化avplayer状态 
          break; 
        case 'released': 
          console.info('AVPlayer state released called.'); 
          break; 
        default: 
          console.info('AVPlayer state unknown called.'); 
          break; 
      } 
    }) 
  } 
  
  // 以下demo为使用fs文件系统打开沙箱地址获取媒体文件地址并通过url属性进行播放示例 
  async avPlayerUrlDemo() { 
    // 创建avPlayer实例对象 
    let avPlayer: media.AVPlayer = await media.createAVPlayer(); 
    // 创建状态机变化回调函数 
    this.setAVPlayerCallback(avPlayer); 
    let fdPath = 'fd://'; 
    // 通过UIAbilityContext获取沙箱地址filesDir，以Stage模型为例 
    let context = getContext(this) as common.UIAbilityContext; 
    let pathDir = context.filesDir; 
    let path = pathDir + '/01.mp3'; 
    // 打开相应的资源文件地址获取fd，并为url赋值触发initialized状态机上报 
    let file = await fs.open(path); 
    fdPath = fdPath + '' + file.fd; 
    this.isSeek = true; // 支持seek操作 
    avPlayer.url = fdPath; 
  } 
  
  // 以下demo为使用资源管理接口获取打包在HAP内的媒体资源文件并通过fdSrc属性进行播放示例 
  async avPlayerFdSrcDemo() { 
    // 创建avPlayer实例对象 
    let avPlayer: media.AVPlayer = await media.createAVPlayer(); 
    // 创建状态机变化回调函数 
    this.setAVPlayerCallback(avPlayer); 
    // 通过UIAbilityContext的resourceManager成员的getRawFd接口获取媒体资源播放地址 
    // 返回类型为{fd,offset,length},fd为HAP包fd地址，offset为媒体资源偏移量，length为播放长度 
    let context = getContext(this) as common.UIAbilityContext; 
    let fileDescriptor = await context.resourceManager.getRawFd('01.mp3'); 
    let avFileDescriptor: media.AVFileDescriptor = 
      { fd: fileDescriptor.fd, offset: fileDescriptor.offset, length: fileDescriptor.length }; 
    this.isSeek = true; // 支持seek操作 
    // 为fdSrc赋值触发initialized状态机上报 
    avPlayer.fdSrc = avFileDescriptor; 
  } 
  
  // 以下demo为使用fs文件系统打开沙箱地址获取媒体文件地址并通过dataSrc属性进行播放(seek模式)示例 
  async avPlayerDataSrcSeekDemo() { 
    // 创建avPlayer实例对象 
    let avPlayer: media.AVPlayer = await media.createAVPlayer(); 
    // 创建状态机变化回调函数 
    this.setAVPlayerCallback(avPlayer); 
    // dataSrc播放模式的的播放源地址，当播放为Seek模式时fileSize为播放文件的具体大小，下面会对fileSize赋值 
    let src: media.AVDataSrcDescriptor = { 
      fileSize: -1, 
      callback: (buf: ArrayBuffer, length: number, pos: number | undefined) => { 
        let num = 0; 
        if (buf == undefined || length == undefined || pos == undefined) { 
          return -1; 
        } 
        num = fs.readSync(this.fd, buf, { offset: pos, length: length }); 
        if (num > 0 && (this.fileSize >= pos)) { 
          return num; 
        } 
        return -1; 
      } 
    } 
    let context = getContext(this) as common.UIAbilityContext; 
    // 通过UIAbilityContext获取沙箱地址filesDir，以Stage模型为例 
    let pathDir = context.filesDir; 
    let path = pathDir  + '/01.mp3'; 
    await fs.open(path).then((file: fs.File) => { 
      this.fd = file.fd; 
    }) 
    // 获取播放文件的大小 
    this.fileSize = fs.statSync(path).size; 
    src.fileSize = this.fileSize; 
    this.isSeek = true; // 支持seek操作 
    avPlayer.dataSrc = src; 
  } 
  
  // 以下demo为使用fs文件系统打开沙箱地址获取媒体文件地址并通过dataSrc属性进行播放(No seek模式)示例 
  async avPlayerDataSrcNoSeekDemo() { 
    // 创建avPlayer实例对象 
    let avPlayer: media.AVPlayer = await media.createAVPlayer(); 
    // 创建状态机变化回调函数 
    this.setAVPlayerCallback(avPlayer); 
    let context = getContext(this) as common.UIAbilityContext; 
    let src: media.AVDataSrcDescriptor = { 
      fileSize: -1, 
      callback: (buf: ArrayBuffer, length: number) => { 
        let num = 0; 
        if (buf == undefined || length == undefined) { 
          return -1; 
        } 
        num = fs.readSync(this.fd, buf); 
        if (num > 0) { 
          return num; 
        } 
        return -1; 
      } 
    } 
    // 通过UIAbilityContext获取沙箱地址filesDir，以Stage模型为例 
    let pathDir = context.filesDir; 
    let path = pathDir  + '/01.mp3'; 
    await fs.open(path).then((file: fs.File) => { 
      this.fd = file.fd; 
    }) 
    this.isSeek = false; // 不支持seek操作 
    avPlayer.dataSrc = src; 
  } 
  
  // 以下demo为通过url设置网络地址来实现播放直播码流的demo 
  async avPlayerLiveDemo() { 
    // 创建avPlayer实例对象 
    let avPlayer: media.AVPlayer = await media.createAVPlayer(); 
    // 创建状态机变化回调函数 
    this.setAVPlayerCallback(avPlayer); 
    this.isSeek = false; // 不支持seek操作 
    avPlayer.url = 'http://xxx.xxx.xxx.xxx:xx/xx/index.m3u8'; 
  } 
}
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