bootstrap的下拉多选框如何使用

<select class="selectpicker" data-style="btn-primary">

  ...

</select>

<select class="selectpicker" data-style="btn-info">

  ...

</select>

<select class="selectpicker" data-style="btn-success">

  ...

</select>

<select class="selectpicker" data-style="btn-warning">

  ...

</select>

<select class="selectpicker" data-style="btn-danger">

  ...

</select>

<select class="selectpicker" data-live-search="true">....</select>

<select class="selectpicker form-control" multiple data-max-options="2">...</select>

<select class="selectpicker" multiple data-live-search="true" data-live-search-placeholder="搜索"

data-actions-box="true">

　　<optgroup label="filter1">

　　　　<option>option1</option>

　　　　<option selected>option2</option>

　　　　<option>option3</option>

　　　　<option>option4</option>

　　</optgroup>

　　<optgroup label="filter2">

　　　　<option>option1</option>

　　　　<option>option2</option>

　　　　<option>option3</option>

　　　　<option>option4</option>

　　</optgroup>

　　<optgroup label="filter3">

　　　　<option>option1</option>

　　　　<option>option2</option>

　　　　<option>option3</option>

　　　　<option>option4</option>

　　</optgroup>

</select>

$('.selectpicker').selectpicker('val','mustard');

$('.selectpicker').selectpicker('val',['mustard','relish']);

$('.selectpicker').selectpicker('refresh');

$('.selectpicker').on('changed.bs.select',function(e){

});