用jquery ajax做的select菜单，选中的效果

//用server端语言赋值给js变量
    var departmentId = '<%=提交的值 %>', deviceId='<%=提交的值 %>'
    $(function () {
        $.ajax({
            url: "deJson.action",
            type: 'POST',
            dataType: 'JSON',
            timeout: 5000,
            //error: function() {alert('载入数据异常，请重试!');},
            success: function (data) {
                //$("#departmentId").empty();
                $.each(eval(data), function (i, item) {
                    $("<option value='" + item.id + "'"+(item.id==departmentId?

' selected':'')+">" + item.name + "</option>").appendTo($("#departmentId"));
                });
            }
        });
        $("#departmentId").click(function () {
            loadDevice($("#departmentId").val());
        });

        function loadDevice(departmentId) {
            $.ajax({
                url: 'dJson.action?

departmentId=' + departmentId,
                type: 'POST',
                dataType: 'JSON',
                timeout: 5000,
                error: function () { alert('载入数据异常，请重试!'); },
                success: function (msg) {
                    if (msg == "{[]}") {
                        $("#deviceId").empty();
                        $("<option value='0'>查询全部</option>").appendTo($("#deviceId"));
                    } else {
                        $("#deviceId").empty();
                        $("<option value='0'>查询全部</option>").appendTo($("#deviceId"));
                        $.each(eval(msg), function (i, item) {
                            $("<option value='" + item.deviceId + "'" + (item.id == deviceId ?

 ' selected' : '') + ">" + item.name + "</option>").appendTo($("#deviceId"));
                        });
                    }
                }
            });
        }
    })

问题描写叙述：
用jquery ajax做的二级联动菜单。联动效果实现了，如今想实现另外一个效果,怎样在表单提交后让刚才选择的下拉菜单项为选中状态？
脚本部分