解决小程序在线上无法显示背景图的问题

 <view class="bannerbj" style="background-image:url({{background}})">

  </view>

data: {
    background: "/img/banner.png",
  },
  onLoad() {
    var that = this;
    let base64 = wx.getFileSystemManager().readFileSync(that.data.background, 'base64');
    that.setData({
      background: 'data:image/jpg;base64,' + base64,
    });
  },