File input 的样式和文字的更改方法
<style>
#uploadImg{ font-size:12px; overflow:hidden; position:absolute}
#file{ position:absolute; z-index:100; margin-left:-180px; font-size:60px;opacity:0;filter:alpha(opacity=0); margin-top:-5px;}
</style>

<span id="uploadImg">
<input type="file" id="file" size="1" >
<a href="#">上传图片</a> </span>