<view class='bg'>
<image src='../assets/bg.png' class='full'></image>
</view>
/* 给盒子添加绝对定位，让图片占满全屏幕 */
.bg {
width: 100%;
height: 100%;
position: absolute;
z-index: -99999;
}
.bg image {
width: 100%;
height: 100%;
}