flex实现图片垂直居中

方案一：flex

.imgview_inner{height: 500px;
    display: -webkit-box;
    display: -webkit-flex;
    display: flex;
    -webkit-box-align: center;
    -webkit-align-items: center;
    align-items: center;
    -webkit-box-pack: center;
    -webkit-justify-content: center;
    justify-content: center;
}

<div class="imgview_inner"><img src="http://gameweb-img.qq.com/gad/20170317/phphgAjtN.1489739479.jpg"></div>

方案二：transform

<div>
    <img src="img.png" alt="">
</div>

div{
    position:relative;
}
img{
    position: absolute;
    left: 50%;top: 50%;
    transform: translate(-50%,-50%);
}