这个是demo，我就直接上代码和需求了，复制粘贴就能用。
先附上效果图：
需要三张图片：
wxml代码：
<view>
<image src="{{shifouplay?'/images/music-stop.png':'/images/music-start.png'}}" class='pic' catchtap='playMusic'></image>
</view>
wxss代码：
.pic{
height: 100rpx;
width: 100rpx;
float: right;
}
js代码：
playMusic: function(ev) {
var shifouplay = this.data.shifouplay;
if (shifouplay) {
wx.pauseBackgroundAudio();
this.setData({
shifouplay: false
})
} else {
wx.playBackgroundAudio({
dataUrl: 'http://ws.stream.qqmusic.qq.com/M500001VfvsJ21xFqb.mp3?guid=ffffffff82def4af4b12b3cd9337d5e7&uin=346897220&vkey=6292F51E1E384E061FF02C31F716658E5C81F5594D561F2E88B854E81CAAB7806D5E4F103E55D33C16F3FAC506D1AB172DE8600B37E43FAD&fromtag=46',
title: '这是歌名',
coverImgUrl: 'http://y.gtimg.cn/music/photo_new/T002R300x300M000003rsKF44GyaSk.jpg?max_age=2592000'
})
this.setData({
shifouplay: true
})
}
}
