Asp.net callback technique Callback study notes
- 2021-01-02 21:48:14
- OfStack
.aspx:
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title> No title page </title>
<script type="text/javascript">
// Pass parameters to the server
function DoSearch(){
var firstName=document.getElementById("TextBox1").value;
CallServer(firstName,"");
}
// Get the data from the server
function ReceiveServerData(txtUserInfo){
Results.innerHTML=txtUserInfo;
}
// Set each 1 Seconds to perform 1 time
setInterval("DoSearch()",1000);
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
The name :<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<br />
<span id="Results" style=" width:500px;"></span>
</div>
</form>
</body>
</html>
[/code]
.aspx.cs
[code]
using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Data.SqlClient;
public partial class _Default : System.Web.UI.Page, ICallbackEventHandler
{
protected string txtUserInfo;
protected void Page_Load(object sender, EventArgs e)
{
// To obtain 1 A reference to a client function
string cbReference = Page.ClientScript.GetCallbackEventReference(this, "arg", "ReceiveServerData", "context");
// Dynamically registers callback functions
string callbackScript = "function CallServer(arg,context)" + "{" + cbReference + "};";
// trigger callbackScript
Page.ClientScript.RegisterStartupScript(this.GetType(), "CallServer", callbackScript, true);
}
// trigger Callback The event processing
public void RaiseCallbackEvent(string txtFirstName)
{
if (txtFirstName != null)
{
String connString = System.Configuration.ConfigurationManager.ConnectionStrings["sqlserver2008"].ToString();
SqlConnection conn = new SqlConnection(connString);
conn.Open();
SqlCommand comm = new SqlCommand("select * from zzx where [name]=@name", conn);
comm.Parameters.Add("@name", SqlDbType.VarChar).Value = txtFirstName;
SqlDataReader reader = comm.ExecuteReader(CommandBehavior.CloseConnection);
if (reader.Read())
{
txtUserInfo = " Employee number :" + reader["id"].ToString() + "<br>";
txtUserInfo += " Employee name :" + reader["name"].ToString() + "<br>";
txtUserInfo += " address :" + reader["address"].ToString() + "<br>";
txtUserInfo += " Server query time :" + DateTime.Now.ToString();
}
else
{
if (string.IsNullOrEmpty(txtFirstName))
{
txtUserInfo = " Please enter your name ";
}
else
{
txtUserInfo = " No such person ";
}
}
comm.Dispose();
reader.Dispose();
conn.Dispose();
}
}
// Get the result of the callback , Return to the client
public string GetCallbackResult()
{
return txtUserInfo;
}
}
Simplified version (lazy 1):
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title> No title page </title>
<script type="text/javascript">
function OnCallBack(txtUserInfo,context){
Results.innerHTML=txtUserInfo;
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
The name :<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<input id="Button2" type="button" value="button"
onclick="<%=Page.ClientScript.GetCallbackEventReference(this, "document.getElementById('TextBox1').value", "OnCallBack",null)%>" />
<br />
<span id="Results" style="pink; width: 500;"></span>
</div>
</form>
</body>
</html>
.aspx.cs
using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Data.SqlClient;
using System.Text;
public partial class _Default : System.Web.UI.Page, ICallbackEventHandler
{
protected StringBuilder txtUserInfo;
protected void Page_Load(object sender, EventArgs e)
{
}
public string GetCallbackResult()
{
return txtUserInfo.ToString();
}
public void RaiseCallbackEvent(string txtFirstName)
{
txtUserInfo = new StringBuilder();
String connString = ConfigurationManager.ConnectionStrings["sqlserver2008"].ToString();
SqlConnection conn = new SqlConnection(connString);
conn.Open();
SqlCommand comm = new SqlCommand("select * from zzx where [name]=@name", conn);
comm.Parameters.Add("@name", SqlDbType.VarChar).Value = txtFirstName;
SqlDataReader reader = comm.ExecuteReader(CommandBehavior.CloseConnection);
if (reader.Read())
{
txtUserInfo.Append(" Employee number :" + reader["id"].ToString() + "<br>");
txtUserInfo.Append(" Employee name :" + reader["name"].ToString() + "<br>");
txtUserInfo.Append(" address :" + reader["address"].ToString() + "<br>");
txtUserInfo.Append(" The query time :" + DateTime.Now.ToString());
}
else
{
if (txtFirstName == string.Empty)
{
txtUserInfo.Append(" Please enter your name ");
}
else
{
txtUserInfo.Append(" No such person ");
}
reader.Dispose();
comm.Dispose();
conn.Dispose();
}
}
}Example 3:
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default3.aspx.cs" Inherits="Default3" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title> No title page </title>
<script type="text/javascript">
// Methods executed by the client
// The following method receives and processes the results returned by the server method
function Success(args,context){
message.innerHTML=args;
}
// The following method is called when an exception occurs to the result handled by the receiving server method
function Error(){
message.innerHTML=" Something is wrong !";
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
The user name :<input type="text" id="txtUserName" onblur="CallServerMethod(txtUserName.value,null)" />
<span id="message"></span>
<br />
password :<input type="password" size="10" maxlength="20" id="txtPwd" />
</div>
</form>
</body>
</html>
[code]
public partial class Default3 : System.Web.UI.Page,ICallbackEventHandler // implementation ICallbackEventHandler interface
{
String result = String.Empty;
protected void Page_Load(object sender, EventArgs e)
{
// Gets the current page of ClientScriptManager A reference to the
ClientScriptManager csm = Page.ClientScript;
/* Gets a reference to the callback . Will be generated on the client side WebForm_DoCallback methods ,
* Call it to make an asynchronous call . This method is the method written by Microsoft , Will be sent
To the client */
/* Notice that the "Success" and Error The two strings are in the client code
* Two definitions javascript function */
// The following method is final 1 The meaning of the parameters :true Means to perform an asynchronous callback ,false Flags perform a synchronous callback
String reference = csm.GetCallbackEventReference(this, "args", "Success", "", "Error", true);
String callbackScript = "function CallServerMethod(args,context){\n"+
reference+";\n }";
// Register with the current page javascript Script code
csm.RegisterClientScriptBlock(this.GetType(), "CallServerMethod",callbackScript,true);
}
#region ICallbackEventHandler Members of the
/// <summary>
/// A method that returns the result of a callback method execution
/// </summary>
public string GetCallbackResult()
{
return result;
}
/// <summary>
/// Run the callback method on the server side
/// </summary>
public void RaiseCallbackEvent(string eventArgument)
{
if (eventArgument.ToLower().IndexOf("admin")!=-1)
{
result =eventArgument+ " Cannot be registered as a user .";
}
else
{
result = eventArgument + " You can register .";
}
}
#endregion
}