html:

这里的下拉列表数据从若依字典里取值

<li>
	<input type="hidden" class="form-control" name="channelsList" id="channelsList" >
	渠道：
	<select name="channels" id="channels" th:with="dictList=${@dict.getType('talent_channel')}" class="selectpicker" title="全部" multiple data-live-search="true" data-selected-text-format="count > 2">
		<option th:each="dict : ${dictList}" th:text="${dict.dictLabel}"
				th:value="${dict.dictValue}"></option>
	</select>
</li>
<li style="float: right;padding-right: 60px;">
	<a class="btn btn-primary btn-rounded btn-sm" onclick="doSubmit(),$.table.search()"><i class="fa fa-search"></i>&nbsp;搜索</a>
	<a class="btn btn-warning btn-rounded btn-sm" onclick="$.form.reset(),doReset()"><i class="fa fa-refresh"></i>&nbsp;重置</a>
</li>

js声明两个方法：提交时获取多选数据，重置时重置多选下拉框

function doSubmit(){
	var str=[];
	$("#channels option:selected").each(function () {
		str.push($(this).val());// 收集选中项
	})
	$("#channelsList").val(str);//后端通过获取表单数据channelsList获取多选内容(字符串或数组接收)
}
function doReset() {
	$("#channels").selectpicker('refresh');//重置下拉框
}