微信小程序 音频和背景音频的无缝切换播放

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音频播放

微信小程序目前建议要使用音频的功能，推荐使用通过wx.createInnerAudioContext()创建内部 audio 上下文 InnerAudioContext 对象。

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<!--seek：跳转的位置，auto: 是否自动播放-->
handleAudio(seek=0,auto=true){
    const that=this
    this.setData({
      innerAudioContext: wx.createInnerAudioContext()
    })
    this.data.innerAudioContext.seek(seek)
    <!--这里的url指的是音频的地址-->
    this.data.innerAudioContext.src = url
    if(auto){
      this.data.innerAudioContext.autoplay = true
    }
    this.data.innerAudioContext.onPlay(() => {
      console.log('开始播放')
    })
    this.data.innerAudioContext.onTimeUpdate(()=>{
      <!--持续更新已播放的进度-->
      that.setData({
        currentTime: that.formatTime(that.data.innerAudioContext.currentTime)
      })
    })
    this.data.innerAudioContext.onError((res) => {
      console.log(res.errMsg)
      console.log(res.errCode)
    })
  }

接着在页面生命周期onReady里使用wx.request的success里去调用handleAudio函数。

背景音频播放

如果用户离开音频播放页面，如何是音频接着播放，这里就是用到了背景音频。

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playBackground(){
    wx.setStorageSync('work_id', this.data.work_id)
    if (this.data.innerAudioContext.paused == false) {
      <!--销毁音频实例-->
      this.data.innerAudioContext.destroy()
      const backgroundAudioManager = wx.getBackgroundAudioManager()

      <!--this.data.work:从API获取的数据-->
      backgroundAudioManager.title = this.data.work.title
      backgroundAudioManager.epname = this.data.work.title
      backgroundAudioManager.singer = this.data.work.author.name
      backgroundAudioManager.startTime = this.data.innerAudioContext.currentTime
      backgroundAudioManager.coverImgUrl = this.data.work.author.avatar[0].url
      // 设置了 src 之后会自动播放
      backgroundAudioManager.src = this.data.work.audio[0].url
    }
  }

接着在页面生命周期onHide和onUnload里调用playBackground函数。

完整代码

wxml

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    <!--pages/work/index.wxml-->
<view class='container'>
  <i-message id="message" />
  <!-- <image class='poster' src="{{work.poster[0].url}}" mode='widthFix'></image> -->
  <image-loader  
    style="width:100%"
    default-image='/assets/images/def_poster.jpg' 
    mode='widthFix'     
    original-image='{{work.poster[0].url}}'
    width="100%" />
  <view class='active-audio'>
    <view class='audio-left'>
      <!-- <image src='{{work.author.avatar[0].url}}' mode='widthFix'></image> -->
      <image-loader  
        style="width:100%"
        default-image='/assets/images/def_avatar.jpg' 
        mode='widthFix'     
        original-image='{{work.author.avatar[0].url}}'
        width="100%" />
      <view class='play' wx:if="{{!paly_status}}" bindtap='play'>
        <text class='play-btn'></text>
      </view>
      <view class="stop"  wx:if="{{paly_status}}" bindtap='stop'>
        <text class='stop-left'></text>
        <text class='stop-right'></text>
      </view>
    </view>
    <view class='audio-right'>
      <text class='top'>{{work.title}}</text>
      <view class='bottom'>
        <text>{{work.author.name}}</text>
        <view class='time' wx:if="{{duration!='00:00'}}">
          <text>{{currentTime}}/</text>
          <text>{{duration}}</text>
        </view>
      </view>
    </view>
  </view>
  <view class='youtube'>
    <text>YouTube:</text>
    <text class='url'>{{work.video_src}}</text>
  </view>
  <view class="action">
    <view class='action-item' open-type="share">
      <button 
        bindtap="handleTapShareButton" 
        open-type="share" 
        class="button-share" 
        id="share-button">
      </button>
      <label for="share-button"><i-icon size='24' type="send" />
      <text>分享</text></label>
    </view>
    <view class='action-item' bindtap='handleCollect'>
      <i-icon size='24' type="{{collect_status?'collection_fill':'collection'}}" />
      <text>{{collect_status?'已收藏':'收藏'}}</text>
    </view>
  </view>
</view>

wxss

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/* pages/work/index.wxss */

.container {
  text-align: center;
  padding: 0 20rpx;
}

.poster {
  width: 100%;
  border-radius: 5px;
}

.action {
  display: flex;
  justify-content: center;
  margin: 10px 0;
}

image{
  border-radius: 5px;
}
.action-item {
  margin: 0 20px;
  display: flex;
  align-items: center;
}

.action-item label {
  display: flex;
  align-items: center;
}

.action text {
  font-size: 18px;
  color: #515151;
}

.button-share {
  display: none;
}

.youtube {
  margin-top: 20px;
  text-align: left;
}

.youtube .url {
  word-wrap: break-word;
  color: rgb(0, 0, 238);
  text-decoration: underline;
  margin: 5px;
}

.active-audio {
  margin-top: 10px;
  width: 100%;
  display: flex;
  border: 1px solid #e0e0e0;
  border-radius: 2px;
}

.audio-left {
  position: relative;
  width: 80px;
  height: 80px;
}

.audio-left image {
  border-radius: 0;
}

.play {
  position: absolute;
  top: 25px;
  left: 25px;
  border: 1px solid #fff;
  display: inline-block;
  height: 30px;
  width: 30px;
  border-radius: 50%;
}

.play-btn {
  position: absolute;
  top: 7px;
  left: 10px;
  display: inline-block;
  width: 0;
  height: 0;
  border-top: 8px solid transparent;
  border-left: 12px solid rgba(255, 255, 255, 0.9);
  border-bottom: 8px solid transparent;
}

.stop {
  position: absolute;
  top: 25px;
  left: 25px;
  border: 1px solid #fff;
  display: inline-block;
  height: 30px;
  width: 30px;
  border-radius: 50%;
}

.stop-left, .stop-right {
  position: absolute;
  top: 9px;
  display: inline-block;
  width: 0;
  height: 0;
  border-color: rgba(255, 255, 255, 0.9);
  border-style: solid;
  border-width: 6px 2px;
}

.stop-left {
  left: 9px;
}

.stop-right {
  right: 9px;
}

.audio-right {
  position: relative;
  width: calc(100% - 104px);
  margin: 0 12px;
  text-align: left;
  height: 80px;
}
.audio-right .top {
  padding-top: 5px;
  display: -webkit-box;
  overflow: hidden;
  text-overflow: ellipsis;
  word-break: break-all;
  -webkit-box-orient: vertical;
  -webkit-line-clamp: 2;
}

.bottom {
  width: 100%;
  display: flex;
  justify-content: space-between;
  font-size: 14px;
  color: #8b8b8b;
  position: absolute;
  bottom: 5px;
}
.time{
  font-size: 14px;
}

js

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const utils = require('../../utils/util.js')
const { $Message } = require('../../utils/iview/base/index');
const app = getApp()
// pages/work/index.js
Page({

  /**
   * 页面的初始数据
   */
  data: {
    work:{},
    work_id:null,
    collect_status: false,
    innerAudioContext:null,
    time:0,
    duration:"00:00",
    currentTime:'00:00',
    paly_status:false
  },
  
  /**
   * 根据id获取作品
   */
  getWork(id=3,seek=0,auto=true){
    utils.wxRequest(`/work/${id}`,{
      query: {
        qiniu:true
      }
    })
      .then(res => {
        this.setData({
          work:res.data
        });
        this.setData({
          time: res.data.time,
          duration: res.data.formatTime
        })
        // const audioCtx = wx.createAudioContext('myAudio')
        // audioCtx.play()
        this.handleAudio(seek,auto)
      })
  },

  /**
   * 格式化事件
   */
  formatTime(cellValue){
    if (cellValue){
      let hour = parseInt(cellValue / 3600)
      let min = parseInt((cellValue - hour * 3600) / 60)
      min = min < 10 ? '0' + min : min
      let sec = parseInt(cellValue % 60)
      sec = sec < 10 ? '0' + sec : sec
      if (hour > 0) {
        return hour + ':' + min + ':' + sec
      }
      return min + ':' + sec
    }
  },

  /**
   * 播放音频
   */
  handleAudio(seek=0,auto=true){
    const that=this
    this.setData({
      innerAudioContext: wx.createInnerAudioContext()
    })
    this.data.innerAudioContext.seek(seek)
    this.data.innerAudioContext.src = this.data.work.audio[0].url
    if(auto){
      this.data.innerAudioContext.autoplay = true
    }
    this.data.innerAudioContext.onPlay(() => {
      that.setData({
        paly_status:true
      })
      console.log('开始播放')
    })
    this.data.innerAudioContext.onTimeUpdate(()=>{
      that.setData({
        currentTime: that.formatTime(that.data.innerAudioContext.currentTime)
      })
    })
    this.data.innerAudioContext.onError((res) => {
      console.log(res.errMsg)
      console.log(res.errCode)
    })
  },

  /**
   * 播放
   */
  play(){
    this.data.innerAudioContext.play()
    this.setData({
      paly_status: true
    })
  },

  /**
   * 停止
   */
  stop(){
    this.data.innerAudioContext.pause()
    this.setData({
      paly_status: false
    })
  },

  /**
   * 获取收藏状态
   */
  getCollectByUser(id) {
    utils.wxRequest(`/user/collect/${id}`, {
      method: 'GET',
      header: {
        Authorization: 'Bearer ' + app.globalData.token
      }
    }).then(res => {
      if (res.collect == true) {
        this.setData({
          collect_status: true
        })
      }
    }).catch(err => {
      console.log(err)
    })
  },

  /**
   * 收藏操作
   */
  handleCollect(){
    utils.wxRequest('/user/collect', {
      method: 'POST',
      query: {
        work_id: this.data.work.id,
        collect: this.data.collect_status
      },
      header: {
        Authorization: 'Bearer ' + app.globalData.token
      }
    }).then(res => {
      this.setData({
        collect_status: !this.data.collect_status
      })
      $Message({
        content: res.message,
        duration: 1,
        type: 'success'
      });
    }).catch(err => {
      console.log(err)
    })
  },

  /**
   * 后台播放
   */
  playBackground(){
    wx.setStorageSync('work_id', this.data.work_id)
    if (this.data.innerAudioContext.paused == false) {
      this.data.innerAudioContext.destroy()
      const backgroundAudioManager = wx.getBackgroundAudioManager()

      backgroundAudioManager.title = this.data.work.title
      backgroundAudioManager.epname = this.data.work.title
      backgroundAudioManager.singer = this.data.work.author.name
      backgroundAudioManager.startTime = this.data.innerAudioContext.currentTime
      backgroundAudioManager.coverImgUrl = this.data.work.author.avatar[0].url
      // 设置了 src 之后会自动播放
      backgroundAudioManager.src = this.data.work.audio[0].url
    }
  },

  /**
   * 生命周期函数--监听页面加载
   */
  onLoad: function (options) {
    this.setData({
      work_id: options.id
    })
  },

  /**
   * 生命周期函数--监听页面初次渲染完成
   */
  onReady: function () {
    this.getCollectByUser(this.data.work_id)
  },

  /**
   * 生命周期函数--监听页面显示
   * 根据storge判断work_id是否相同,再根据后台播放状态判断
   */
  onShow: function () {
    const work_id = wx.getStorageSync('work_id')||null
    if(work_id!=null && work_id==this.data.work_id){
      const backgroundAudioManager = wx.getBackgroundAudioManager()
      if (backgroundAudioManager.paused==false){
        backgroundAudioManager.pause()
        this.getWork(this.data.work_id, backgroundAudioManager.currentTime)
      }else{
        this.getWork(this.data.work_id)
      }
    }else{
      wx.pauseBackgroundAudio()
      this.getWork(this.data.work_id)
    }
  },

  /**
   * 生命周期函数--监听页面隐藏
   * 根据audio播放状态去启动后台播放
   */
  onHide: function () {
    this.playBackground()
  },

  /**
   * 根据audio播放状态去启动后台播放
   * 生命周期函数--监听页面卸载
   */
  onUnload: function () {
    this.playBackground()
  },

  /**
   * 页面相关事件处理函数--监听用户下拉动作
   */
  onPullDownRefresh: function () {

  },

  /**
   * 页面上拉触底事件的处理函数
   */
  onReachBottom: function () {

  },

  /**
   * 用户点击右上角分享
   */
  onShareAppMessage: function () {

  }
})

实际效果

参考资料

  1. 微信小程序
  2. ECMAScript 6 入门