<form>
<span style="width:0;overflow:hidden"><input type=file name=f></span>
<button onclick="f.click()">open</button>
</form>
<span style="width:0;overflow:hidden"><input type=file name=f></span>
<button onclick="f.click()">open</button>
</form>
<input type=file name=ff id=ff style="display: none" onChange="document.form1.f1.value=this.value">
<input name=f1 readonly><input type=button value=浏览文件 onclick="document.form1.ff.click()">
</form>