如何用图片按钮来代替文件上传控件

<style type="text/css">

.fileInputContainer{
height:256px;
background:url(http://images.cnblogs.com/cnblogs_com/dreamback/437546/o_ff6.png);
position:relative;
width: 256px;
}
.fileInput{
height:256px;
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>