Web實現點擊圖片彈出上傳文件窗口

<style>
 .fileInputContainer{
        height:256px;
        background:url(upfile.png);
        position:relative;
        width: 256px;
    }
    .fileInput{
        height:256px;
        overflow: hidden;
        font-size: 300px;
        position:absolute;
        right:0;
        top:0;
        opacity: 0;
        filter:alpha(opacity=0);
        cursor:pointer;
    }
</style>

<div class="fileInputContainer">
    <input class="fileInput" type="file" name="" id="" />
</div>