<%

String context = request.getContextPath();

String index = (String)request.getAttribute("index");  //获取后台传来下拉框的值

%>

$('select').children('option').each(function(){

    if($(this).val()=='<%=index%>'){

        $(this).prop('selected',true);

    }

});

<div align="center">

    <select>

        <option value="">请选择</option>

        <option value="1">北京</option>

        <option value="2">上海</option>

        <option value="3">深圳</option>

        <option value="4">广州</option>

    </select>

</div>