微信小程序实现音乐播放器（4）（使用pubsubjs实现页面间通信）

前情提要

消息订阅与发布的基本使用

1. npm install --save pubsub-js，安装第三方库pubsub-js。
2. import PubSub from "pubsub-js"，引入第三方库pubsub。
3. 订阅消息：id = PubSub.subscribe(消息名,callback)，且callback的第一个形参默认是消息名，后面则是开发者自己传入的参数。
4. 发布消息：PubSub.publish(消息名,开发者的参数)。
5. 取消订阅：PubSub.unsubscribe(id)。

小程序项目

1. 初始化项目。小程序根目录下执行npm init -y，自动生成package.json。
2. 下载安装依赖。npm install --save pubsub-js。
3. 页面pages/music/music.js中引入依赖。import PusSub from "pubsub-js"。
   遇到如下报错：页面【pages/music/music]错误:
   Error: module ‘pages/music/pubsub-js.js’ is not defined, require args is ‘pubsub-js’。
4. 微信开发者工具中，工具 > 构建npm，会自动把node_modules中的第三方依赖转换成小程序可以使用的包，并保存在同级文件夹miniprogram_npm中。
   
5. 消息订阅：消息ID=PubSub.subscribe(消息名,(msgName,接收的数据) => {})
   取消订阅：PubSub.unsubscribe(消息ID)
   消息发布：PubSub.publish(消息名,发送的数据)

小程序代码涉及的主要文件有：

1. app.json
2. app.wxss
3. app.js
4. pages/index/index.json
5. pages/index/index.wxml
6. pages/index/index.wxss
7. pages/index/index.js
8. pages/music/music.json
9. pages/music/music.wxml
10. pages/music/music.wxss
11. pages/music/music.js

app.json

{
    
  "pages": [
    "pages/index/index",
    "pages/music/music"
  ],
  "window": {
    
    "navigationBarBackgroundColor": "#624d2e",
    "navigationBarTitleText": "首页",
    "navigationBarTextStyle": "white"
  },
  "requiredBackgroundModes": [
    "audio"
  ],
  "style": "v2",
  "sitemapLocation": "sitemap.json"
}

app.wxss

page{
    
  height: 100%;
}

app.js

App({
    
  globalData:{
    
    isPlayGlobal:false,   //当前是否有歌曲在播放
    musicIdGlobal:''     //当前正在播放的歌曲是哪首
  }
})

pages/index/index.json

{
    
  "usingComponents": {
    },
  "navigationBarTitleText": "播放列表"
}

pages/index/index.wxml

<view class="index-container">
  <view class="header">
    <image src="/static/images/icon-play-square.png"></image>
    <text>播放全部</text>
    <text>{
   {musicList.length}}</text>
  </view>
  <scroll-view class="music-list" enable-flex scroll-y >
    <view class="music-item" wx:for="{
     {musicList}}" wx:key="id" bindtap="handleTap" data-musicindex="{
     {index}}" data-musicitem="{
     {item}}">
      <view class="music-index">{
   {index+1}}</view>
      <image class="music-image" src="{
     {item.picUrl}}"></image>
      <view class="music-info">
        <view class="musci-name">{
   {item.name}}</view>
        <view class="music-author">{
   {item.author}}</view>
      </view>
      <image class="btn-more" src="/static/images/icon-more.png"></image>
    </view>
  </scroll-view>
</view>

pages/index/index.wxss

.index-container{
    
  padding: 20rpx;
  background:#624d2e
}
.header{
    
  display: flex;
  align-items: center;
}
.header image{
    
  width: 28rpx;
  height: 28rpx;
  margin-right: 20rpx;
}
.header text{
    
  color: #fff;
  height: 28rpx;
  line-height: 28rpx;
  margin-right: 20rpx;
  font-size: 28rpx;
}
.music-list{
    
  margin-top: 20rpx;
  color: #fff;
  height: calc(100vh - 88rpx);
}
.music-item{
    
  display: flex;
  align-items: center;
  height: 100rpx;
  margin: 20rpx 0;
  position: relative;
}
.music-item .music-index{
    
  width: 50rpx;
  font-size: 28rpx;
  color: #aaa;
}
.music-item .music-image{
    
  width: 80rpx;
  height: 80rpx;
  border-radius: 6rpx;
  margin-right: 20rpx;
}
.music-item .music-info{
    
  display: flex;
  flex-direction: column;
}
.music-item .music-info .music-author{
    
  font-size: 24rpx;
  color: #aaa;
  margin-top: 10rpx;
}
.music-item .btn-more{
    
  width: 36rpx;
  height: 36rpx;
  position: absolute;
  right: 0;
}

pages/index/index.js

import PubSub from "pubsub-js";
const host = "http://localhost:3000";

Page({
    
  data:{
    
    musicList:[], //歌曲列表
    musicindex:0  //进入某首歌曲后，记录该歌曲在列表中的索引
  },
  onLoad(){
    
    this.getDataFromServer();

    //接收消息，接收来自页面pages/music/music的消息，根据“上一首”or“下一首”，确定当前应该显示哪首歌曲
    PubSub.subscribe("switchsong",(msgName,type) => {
    
      // console.log(msgName,type);
      let {
    musicindex,musicList} = this.data;
      if(type === "prev"){
    
        if(musicindex===0) {
    
          musicindex = musicList.length-1;
        }else{
    
          musicindex--;
        }
      }else if(type === "next"){
    
        if(musicindex === musicList.length-1){
    
          musicindex = 0;
        }else{
    
          musicindex++;
        }
      }
      this.setData({
    musicindex});
      const music = musicList[musicindex];
      //发送消息，告诉页面pages/music/music，告诉它切换完成后的歌曲的详细消息。
      PubSub.publish("refreshmusic",music);
    })
  },
  getDataFromServer(){
    
    const result = [
      {
    id:"001",name:"滂沱大雨里","author":"李若溪","picUrl":host+"/images/滂沱大雨里.jpg","url":host+"/audios/滂沱大雨里.mp3",duration:161000},
      {
    id:"002",name:"Last Dance","author":"伍佰","picUrl":host+"/images/Last Dance.jpg","url":host+"/audios/Last Dance.mp3",duration:271000},
      {
    id:"003",name:"国王与乞丐","author":"华晨宇","picUrl":host+"/images/国王与乞丐.jpg","url":host+"/audios/国王与乞丐.mp3",duration:178000},
      {
    id:"004",name:"奇洛李维斯回信","author":"薛凯琪","picUrl":host+"/images/奇洛李维斯回信.jpg","url":host+"/audios/奇洛李维斯回信.mp3",duration:243000},
      {
    id:"005",name:"红日","author":"李克勤","picUrl":host+"/images/红日.jpg","url":host+"/audios/红日.mp3",duration:291000},
      {
    id:"006",name:"快乐崇拜","author":"潘玮柏 张韶涵","picUrl":host+"/images/快乐崇拜.jpg","url":host+"/audios/快乐崇拜.mp3",duration:329000},
      {
    id:"007",name:"门没锁","author":"黄品冠","picUrl":host+"/images/门没锁.jpg","url":host+"/audios/门没锁.mp3",duration:233000},
      {
    id:"008",name:"就是爱你","author":"陶喆","picUrl":host+"/images/就是爱你.jpg","url":host+"/audios/就是爱你.mp3",duration:340000},
      {
    id:"009",name:"快乐的小青蛙","author":"刘士鸣","picUrl":host+"/images/快乐的小青蛙.jpg","url":host+"/audios/快乐的小青蛙.mp3",duration:130000},
      {
    id:"0010",name:"友情岁月","author":"陈小春 郑伊健 谢天华 林晓峰 钱嘉乐","picUrl":host+"/images/友情岁月.jpg","url":host+"/audios/友情岁月.mp3",duration:209000},
      {
    id:"0011",name:"温柔","author":"五月天","picUrl":host+"/images/温柔.jpg","url":host+"/audios/温柔.mp3",duration:269000}
    ];
    this.setData({
    musicList:result});
  },
  handleTap(event){
    
    const {
    musicitem,musicindex} = event.currentTarget.dataset;
    this.setData({
    musicindex})
    wx.navigateTo({
    
      url: '/pages/music/music?musicitem='+JSON.stringify(musicitem),
    })
  }
})

pages/music/music.json

{
    
  "usingComponents": {
    },
  "navigationBarBackgroundColor": "#2f434e",
  "navigationBarTitleText": "音乐详情"
}

pages/music/music.wxml

<view class="music-container">
  <view class="music-name">{
   {music.name}}</view>
  <view class="music-author">{
   {music.author}}</view>
  <image class="arm {
     {isPlay&&'arm-reset'}}" src="/static/images/arm.png"></image>
  <view class="disc-container {
     {isPlay&&'disc-animate'}}">
    <image class="disc" src="/static/images/disc.png"></image>
    <image class="music-image" src="{
     {music.picUrl}}"></image>
  </view>
  <view class="player">
    <view class="btns">
      <image class="loop-btn" src="/static/images/loop.png"></image>
      <image class="prev-btn" src="/static/images/prev.png" id="prev" bindtap="handleSwitch"></image>
      <image class="play-btn" src="{
     {isPlay?'/static/images/stop.png':'/static/images/play.png'}}" bindtap="handlePlay"></image>
      <image class="next-btn" src="/static/images/next.png" id="next" bindtap="handleSwitch"></image>
      <image class="list-btn" src="/static/images/list.png"></image>
    </view>
  </view>
</view>

pages/music/music.wxss

.music-container{
    
  height: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  background: #2f434e;
  position: relative;
}
.music-container .music-name{
    
  margin: 10rpx 0;
  color: #fff;
  font-size: 36rpx;
}
.music-container .music-author{
    
  color: #bbb;
  font-size: 28rpx;
  margin: 6rpx 0;
}
.music-container .arm{
    
  width:204rpx;
  height: 358rpx;
  position: relative;
  left: 72rpx;
  z-index: 99;
  transform: rotate(-15deg);
  transform-origin: 30rpx 30rpx;
  transition: transform .7s linear;
}
.disc-container{
    
  position: relative;
  top: -128rpx;
  width: 490rpx;
  height: 490rpx;
}
.disc-container .disc{
    
  width: 100%;
  height: 100%;
}
.disc-container .music-image{
    
  width: 270rpx;
  height: 270rpx;
  border-radius: 100%;
  position: absolute;
  left: 0;right: 0;top: 0;bottom: 0;
  margin: auto;
}
.music-container .arm-reset{
    
  transform: rotate(0deg);
}
.disc-animate{
    
  animation: rotate 2.5s 1s linear infinite;
}
@keyframes rotate{
    
  from{
    
    transform: rotate(0deg);
  }
  to{
    
    transform: rotate(360deg);
  }
}
.player{
    
  width: 100%;
  position: absolute;
  bottom: 60rpx;
}
.btns{
    
  display: flex;
  align-items: center;
  justify-content: space-evenly;
}
.btns image{
    
  width: 36rpx;
  height: 36rpx;
}
.btns .play-btn,.btns .stop-btn{
    
  width: 90rpx;
  height: 90rpx;
}

pages/music/music.js

import PubSub from "pubsub-js";
const appInstance = getApp();

Page({
    
  data:{
    
    isPlay:false,
    music:{
    }
  },
  onLoad(options){
    
    const music = JSON.parse(options.musicitem);
    this.setData({
    music})
    const {
    isPlayGlobal,musicIdGlobal} = appInstance.globalData;
    const {
    id} = this.data.music;
    if(isPlayGlobal && musicIdGlobal === id) {
    
      this.setData({
    isPlay:true});
    }
  
    this.bam = wx.getBackgroundAudioManager();
    this.bam.onPlay(() => {
    
      this.setData({
    isPlay:true})
      appInstance.globalData.isPlayGlobal = true;
      appInstance.globalData.musicIdGlobal = this.data.music.id;
    })
    this.bam.onPause(() => {
    
      this.setData({
    isPlay:false})
      appInstance.globalData.isPlayGlobal = false;
    })
    this.bam.onStop(() => {
    
      this.setData({
    isPlay:false})
      appInstance.globalData.isPlayGlobal = false;
    })
    this.bam.onEnded(() => {
    
      this.setData({
    isPlay:false});
      appInstance.globalData.isPlayGlobal = false;
    })
  },
  handlePlay(){
    
    const isPlay = !this.data.isPlay;
    this.setData({
    isPlay});
    this.musicControl();
  },
  musicControl(){
    
    const {
    isPlay} = this.data;
    if(isPlay){
    
      this.bam.src = this.data.music.url;
      this.bam.title = this.data.music.name;
    }else{
    
      this.bam.pause();
    }
  },
  handleSwitch(event){
    
    const type = event.target.id;
    //发送消息，告诉pages/index/index：切上一首还是下一首。prev代表切上一首，next代表切下一首。
    PubSub.publish("switchsong",type);

    //接收消息，接收来自pages/index/index的消息，显示切换后的歌曲详情
    const eventId = PubSub.subscribe("refreshmusic",(msgName,music) => {
    
      // console.log(msgName,music);
      PubSub.unsubscribe(eventId);
      this.setData({
    music})
      this.musicControl();
    })
  }
})

相关链接

todoList案例（vue版本）（消息订阅与发布实现组件通信）
pubsubjs