实际上,您只能在服务器上创建服务器控件。所以问题是如何将 AJAX 调用响应传递给服务器并强制它刷新页面上的所需区域。
第一个变体
<script type="text/javascript">
$(function () {
$.getJSON("http://www.carqueryapi.com/api/0.3/?callback=?", { cmd: "getMakes", year: "2009" },
function (data) {
//The 'data' variable contains all response data.
var makes = $.map(data.Makes, function (make) { return make.make_display; }).join(";");
document.getElementById("<%= CarMakersHiddenField.ClientID %>").value = makes;
__doPostBack("<%= CarMakersUpdatePanel.ClientID %>", "");
});
});
</script>
<asp:UpdatePanel runat="server" ID="CarMakersUpdatePanel" UpdateMode="Conditional">
<ContentTemplate>
<asp:HiddenField runat="server" ID="CarMakersHiddenField" />
<asp:BulletedList runat="server" ID="MakersList" DisplayMode="LinkButton">
</asp:BulletedList>
</ContentTemplate>
</asp:UpdatePanel>
服务器代码:
protected void Page_Load(object sender, EventArgs e)
{
MakersList.Items.Clear();
foreach (var maker in CarMakersHiddenField.Value.Split(';'))
{
MakersList.Items.Add(maker);
}
}
如果您需要将一些复杂的对象(如制造商对象数组)传递给服务器,则第二种方法更适合。在这种情况下,您可以在客户端将此对象序列化为 JSON 字符串,并在服务器上对其进行反序列化。看起来像以前的版本有一些变化:
<script type="text/javascript">
$(function () {
$.getJSON("http://www.carqueryapi.com/api/0.3/?callback=?", { cmd: "getMakes", year: "2009" },
function (data) {
//The 'data' variable contains all response data.
var serializedString = Sys.Serialization.JavaScriptSerializer.serialize(data.Makes);
document.getElementById("<%= CarMakersHiddenField.ClientID %>").value = serializedString;
__doPostBack("<%= CarMakersUpdatePanel.ClientID %>", "");
});
});
</script>
标记与第一个版本相同。服务器代码:
[Serializable]
public class Make
{
public string make_id;
public string make_display;
public bool make_is_common;
public string make_country;
}
protected void Page_Load(object sender, EventArgs e)
{
MakersList.Items.Clear();
if (!String.IsNullOrEmpty(CarMakersHiddenField.Value))
{
var serializer = new DataContractJsonSerializer(typeof(Make[]));
using (var stream = new MemoryStream(Encoding.Unicode.GetBytes(CarMakersHiddenField.Value)))
{
var makes = serializer.ReadObject(stream) as Make[];
if (makes != null)
{
foreach (var maker in makes)
{
MakersList.Items.Add(new ListItem(maker.make_display, maker.make_id));
}
}
}
}
}