download link:
https://github.com/select2/select2
First import:
<link href="select2.css" rel="stylesheet" type="text/css" />
<script src="select2.min.js" type="text/javascript"></script>And, most importantly jq package
<script src="jquery.min.js"></script>Finally, at the bottom of the bottom of the page, or inside the body
<script type="text/javascript">
//Select2
jQuery(".select2").select2({
width : '100%' //这里的width是当前select显示的宽度，可以随便设置，但是不能等于0
});
</script>If it does, then check the above js wrote place, <head> which does not work, then you put the following pages! ! !
Code:
<select class="select2" id="test" name="test" style="width: 450px; margin-top: 12px;"
onchange="selectColumnSecond(this.value);">
<option value="">---请选择---</option>
<c:forEach items="${list}" var="bc">
<option value="${bc.id}">${bc.colname}</option>
</c:forEach>
</select>