ASP.NET 2.0中callback的一些變化＋使用示例(下)－歡迎~ 程式設計學生作業專題製作程式外包家教...

ASP.NET 2.0中callback的一些變化＋使用示例(下)

本文地址：http://qzone.qq.com/blog/101766959-1217964961

Callback.aspx.cs：
using System;
using System.IO;
using System.Collections;
using System.Globalization;
using System.Reflection;
using System.Web;
using System.Web.UI;

public partial class Callback : Page, ICallbackEventHandler
{
    private string _callbackEventArgument;

    protected void Page_Load(object sender, EventArgs e)
    {
               ddlCategory.Attributes.Add("onchange", "CallServer('FillProduct|'+this.value,_span1)");
               ddlProduct.Attributes.Add("onchange", "CallServer('ShowBuy|'+this.value,_span2)");
           }

    ICallbackEventHandler Members#region ICallbackEventHandler Members

    public string GetCallbackResult()
    {
        string[] parts = _callbackEventArgument.Split('|');
        object[] args = null;
        string result = "";

        if (parts.Length > 1)
        {
                   args = new object[parts.Length - 1];
                   Array.Copy(parts, 1, args, 0, args.Length);
               }

               MethodInfo method = this.GetType().GetMethod(parts[0]);

        if (method != null)
        {
                   result = (string)method.Invoke(this, args);
               }

        return result;
           }

    public void RaiseCallbackEvent(string eventArgument)
    {
               _callbackEventArgument = eventArgument;
           }

    void ICallbackEventHandler.RaiseCallbackEvent(string eventArgument)
    {
        this.RaiseCallbackEvent(eventArgument);
           }

    string ICallbackEventHandler.GetCallbackResult()
    {
        return this.GetCallbackResult();
           }

    #endregion

    public string FillProduct(string categoryID)
    {
               ddlCategory.SelectedValue = categoryID;
               ddlProduct.DataBind();

        return RenderControl(ddlProduct);
           }

    public string ShowBuy(string ProductID)
    {
               btnBuy.Enabled = !string.IsNullOrEmpty(ProductID);

        return RenderControl(btnBuy);
           }

    protected void btnBuy_Click(object sender, EventArgs e)
    {
               _div1.Visible = false;
               Label1.Text = "Buy: " + Request.Form[ddlProduct.UniqueID];
           }

    private string RenderControl(Control control)
    {
               StringWriter writer1 = new StringWriter(CultureInfo.InvariantCulture);
               HtmlTextWriter writer2 = new HtmlTextWriter(writer1);

               control.RenderControl(writer2);
               writer2.Flush();
               writer2.Close();

        return writer1.ToString();
           }
}