效果如图：
代码如下：
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Demo</title>
<script type="text/javascript">
function F_Open_dialog() {
document.getElementById("btn_file").click();
}
</script>
</head>
<body>
<div>
<input type="file" id="btn_file" style="display:none">
<button type="button" onclick="F_Open_dialog()">选择文件</button>
</div>
</body>
</html>
![没救了! 困扰程序员一辈子的5个魔咒, 改掉比登天还难！[图]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=)