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.net2.0客户端回调实现 (C#) 示例

2006-06-05 18:39 302 查看

照搬MSDN2005的代码实现无刷回调，老是提示：
错误1“ClientCallback”不会实现接口成员“System.Web.UI.ICallbackEventHandler.RaiseCallbackEvent(string)”。“ClientCallback.RaiseCallbackEvent(string)”或者是静态、非公共的，或者有错误的返回类型。
错误2“ClientCallback”不会实现接口成员“System.Web.UI.ICallbackEventHandler.GetCallbackResult()”

<%@ Page Language="C#" AutoEventWireup="true"
CodeFile="ClientCallback.aspx.cs" Inherits="ClientCallback" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML
1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<script type="text/javascript">
    function LookUpStock()
    {
        var lb = document.forms[0].ListBox1;
        var product = lb.options[lb.selectedIndex].text
        CallServer(product, "");
    }

    function ReceiveServerData(rValue)
    {
        Results.innerText = rValue;
    }
</script>
</head>
<body>
<form id="form1" runat="server">
    <div>
      <asp:ListBox ID="ListBox1" Runat="server"></asp:ListBox>
      <br />
      <br />
      <button onclick="LookUpStock()">Look Up Stock</button>
      <br />
      <br />
      Items in stock: <span ID="Results"></span>
      <br />
    </div>
</form>
</body>
</html>

// ClientCallback.aspx.cs code-behind page
using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class ClientCallback : System.Web.UI.Page,
     System.Web.UI.ICallbackEventHandler
{
    protected System.Collections.Specialized.ListDictionary catalog;
    protected void Page_Load(object sender, EventArgs e)
    {
        String cbReference =
            Page.ClientScript.GetCallbackEventReference(this,
            "arg", "ReceiveServerData", "context");
        String callbackScript;
        callbackScript = "function CallServer(arg, context)" +
            "{ " + cbReference + "} ;";
        Page.ClientScript.RegisterClientScriptBlock(this.GetType(),
            "CallServer", callbackScript, true);

        catalog = new System.Collections.Specialized.ListDictionary();
        catalog.Add("monitor", 12);
        catalog.Add("laptop", 10);
        catalog.Add("keyboard", 23);
        catalog.Add("mouse", 17);

        ListBox1.DataSource = catalog;
        ListBox1.DataTextField = "key";
        ListBox1.DataBind();
    }

    public String RaiseCallbackEvent(String eventArgument)
    {
        String returnValue;
        if (catalog[eventArgument] == null)
        {
            returnValue = "-1";
        }
        else
        {
            returnValue = catalog[eventArgument].ToString();
        }
        return returnValue;
    }
}

更改后的

//////////////////////////////

    public String RaiseCallbackEvent(String eventArgument)
    {
        String returnValue;
        if (catalog[eventArgument] == null)
        {
            returnValue = "-1";
        }
        else
        {
            returnValue = catalog[eventArgument].ToString();
        }
        return returnValue;
    }

//////////////////////////////

改成如下：

    string earg = "";

    #region ICallbackEventHandler 成员

    public string GetCallbackResult()
    {
        String returnValue;
        if (catalog[earg] == null)
        {
            returnValue = "-1";
        }
        else
        {
            returnValue = catalog[earg].ToString();
        }
        return returnValue;
    }

    public void RaiseCallbackEvent(string eventArgument)
    {
        //throw new Exception("The method or operation is not implemented.");
        earg = eventArgument;
    }

    #endregion

可以体验到了回调的感觉了。。。。。。。。。。。。

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标签： c# .net string function exception keyboard

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