bootstrap 下拉框多选

$(".selectpicker" ).selectpicker('refresh'); 一定要加这句，要不然动态获取不到数据

    <!-- Bootstrap 3.3.7 -->
    <link href="https://cdn.bootcss.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet">
    <!--bootstrap下拉框选择-->
    <link rel="stylesheet" href="js/select/bootstrap-select.min.css">
    <!-- Bootstrap 3.3.7 -->
    <script src="https://cdn.bootcss.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
    <!--bootstrap下拉框选择-->
    <script src="js/select/bootstrap-select.js"></script>   
    <script src="js/select/defaults-zh_CN.min.js"></script>


<select class="form-control selectpicker" id="obj-scan-people" data-style="btn-select" data-live-search="true" multiple title="请选择扫码人">

</select>

<script>
//获取选中的value
 var selectedValues = [];    
$("#obj-scan-people").each(function(){
    selectedValues.push($(this).val()); 
});
function getScanPeople(){
            $('#obj-scan-people').selectpicker('val', ' ');
            var orgCode = $('#obj-school').val();
            ContactsService.getTeachersByOrg(orgCode,function(res){
                if(res.responseCode == 0){
                    var data = JSON.parse(res.responseText);        
                    var htmlItem = '';
                    console.log(data)
                    htmlItem += '<option value="" selected="selected">请选择</option>';
                    for( var i=0;i<data.rows.length;i++ ){
                        var row = data.rows[i]; 
                        htmlItem += '<option value="'+row.field12+'">'+row.field4+'</option>';
                    }
                    $("#obj-scan-people").html(htmlItem);
                    $(".selectpicker" ).selectpicker('refresh'); 
                }else{
                    toastr.error(res.responseText);
                }
            });
        }
</script>