【原】 Web Forums FAQ【JavaScript，User control，Dynamic controls，Mail等10个方面】

这是一篇我和我同事在1年前对Web Fourms 方面的经验总结，本来打算花点时间翻译的，由于目前手头工作实在太多，所以暂且就不翻译了，忘读者多多见谅。具体内容涉及 10 个方面：JavaScript，Pass data between pages，File Upload，Calendar，List controls，User control，Dynamic controls，Style，Print，Mail，具体内容如下：

1 JavaScript

1.1 How to get client date and time

1.2 How to access a control by using JavaScript

1.3 How to invoke a server-side function with JavaScript

1.4 How to retrieve server side variables using JavaScript code

1.5 How to assign a value to a hidden field using JavaScript in ASP.NET

1.6 How to register the JavaScript function at Code-Behind

1.7 How to display images with a delay of five seconds

1.8 How to get browser screen settings and apply it to page controls

1.9 How to clear the session when the user closes a window

2 Ways to pass data between pages

2.1 How to use cookies

2.2 How to use QueryString

2.3 How to use Session

2.4 How to use Context

2.5 How to use PreviousPage

2.6 How to use Submit Form

2.7 How to use Server.Transfer

3 File Upload

3.1 How to upload a file

3.2 How to upload multiple files at once

3.3 Why upload fails when using an ASP.NET FileUpload control to upload large files

3.4 How to upload an image files only

3.5 How to get a File Upload control work with an UpdatePanel

4 Calendar

4.1 How to change the culture settings for a Calendar

4.2 How to select multiple non-sequential dates at Code-Behind

4.3 How to disable some dates in Calendar control

4.4 How to extend Calendar control for Server-Side validation

4.5 How to set ToolTips and links in Calendar control’s DayRender event

4.6 How to give some dates different appearances

5 List controls

5.1 How to enable ASP.NET DropDownList with OptionGroup support

5.2 How to disable an item in DropDownList

5.3 How to hold the selected value for a DropDownList

6 User control

6.1 How to add a new property to UserControl

6.2 How to access a dynamically created UserControl

6.3 How to access a control inside a UserControl

7 Dynamic controls

7.1 How to create a dynamic control

7.2 How to access a user entered value in a dynamic created TextBox control

7.3 Dynamic controls accessed by JavaScript

7.4 How to retain all added server controls dynamically after post back

7.5 Why dynamically created controls disappear after a post back

8 Style

8.1 How to use with Code-Behind

8.2 How to use with JavaScript

8.3 How to remove a space

8.4 How to use with html

8.5 How to set an image as Button’s background

8.6 How to color items in ListBox

9 Print

9.1 How to print a part of a web page with CSS

9.2 How to print a part of a web page with JavaScript (1)

9.3 How to print a part of a web page with JavaScript (2)

10 Mail

10.1 What classes are needed to send e-mails in ASP.NET

10.2 How to send emails by using System.Net.Mail

10.3 How to configure a SMTP Server

10.4 How to send an email with Gmail server

1. JavaScript

1.1 How to get client date and time [top]

You can use java script function to show the date and time.

function displayTime()

{

var localTime = new Date();

var year= localTime.getYear();

var month= localTime.getMonth() +1;

var date = localTime.getDate();

var hours = localTime .getHours();

var minutes = localTime .getMinutes();

var seconds = localTime .getSeconds();

var div=document.getElementById("div1");

div.innerText=year+"-"+month+"-"+date+" "+hours+":"+minutes+":"+seconds;

}

</script>

Then you can call it at web page.

</form>

</body>

http://forums.asp.net/p/1247758/2303034.aspx

1.2 How to access a control by using JavaScript [top]

Reference the ClientID property (or UniqueID) of the control in the JavaScript.

protected void Page_Load(object sender, EventArgs e)

{

Button btn= new Button();

btn.ID = "btn5";

btn.Attributes.Add("runat", "server");

btn.Attributes.Add("onclick", "pop('" + btn.ClientID + "')");

btn.Text = "Test";

this.form1.Controls.Add(btn);

}

function pop(InputBoxID)

{

var InputControl = document.getElementById(InputBoxID);

alert(InputControl.value);

}

Or you can use the following method:

btn.Attributes.Add("onclick", "pop(this)");

function pop(InputBox)

{

alert(InputBox.value);

}

http://forums.asp.net/p/1239593/2260331.aspx#2260331

1.3 How to invoke a server-side function with JavaScript [top]

Firstly, you can drag a server button and put the server function into the button Click even,

protected void Button1_Click(object sender, EventArgs e)

{

FunctionName();

}

Secondly, you can call the server function at JavaScript by using the following code,

document.getElementById("Button1").click();

http://forums.asp.net/p/1242420/2274228.aspx

1.4 How to retrieve server side variables using JavaScript code [top]

<asp:HiddenField ID="HiddenField1" runat="server" />

public partial class LoginDemo : System.Web.UI.Page

{

private string str="hello";

protected void Page_Load(object sender, EventArgs e)

{

HiddenField1.Value=str;

}

Then you can access the control HiddenField1 using javascipt:

Var tt=document.getElementByID(“HiddenField1”);

alert(tt.value);

</script>

http://forums.asp.net/p/1000655/1319119.aspx

1.5 How to assign a value to a hidden field using JavaScript in ASP.NET [top]

We can use JavaScript to set the value of a hidden control and get its value at the server after a post back.

var str=”hello”

document.getElementByID(“Hidden1”).value=str

</script>

protected void Page_Load(object sender, EventArgs e)

{

string str=request["Hidden1"].ToString();

}

http://forums.asp.net/p/1262153/2362090.aspx

1.6 How to register the JavaScript function at Code-Behind [top]

Use ResterStartupScript

this.Page.ClientScript.RegisterStartupScript(this.GetType(),"alert","<script>alert(‘hello’);</script>");

Use Literal control,

private void Button2_Click(object sender, System.EventArgs e)

{

string str;

str="<script language='JavaScript'>";

str+="selectRange()";

str+="<script>";

Literal1.Text=str;

}

http://forums.asp.net/p/981603/1257057.aspx#1257057

1.7 How to display images with a delay of five seconds [top]

With this script you can see clickable images rotating in real-time without requiring banner rotation software or page reloads/refreshes .You should see a new banner rotating every 5 seconds:

<%@ Page Language="C#" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

</script>

<title>JavaScript</title>

var image="";

var banners=0;

function loadbanners() {

if (banners==1)

{

image="images/AJAX.gif";

}

if (banners==2)

{

image="images/ASPDotNet.gif";

}

if (banners==3)

{

image=" images/MSDN.gif";

}

function cycle()

{

if (++banners > 3)

banners=1;

loadbanners();

document.getElementById("banner1").src =image;

window.setTimeout('cycle();',5000);

}

</script>

</head>

<div>

</div>

</form>

</body>

</html>

http://forums.asp.net/p/1213103/2147140.aspx

1.8 How to get browser screen settings and apply it to page controls [top]

You can use the JavaScript, suppose the control type is <image>, see the code below:

<html>

<body>

var winWidth = 0;

var winHeight = 0;

function resizeImage(){

var img=document.getElementById("testImage")

if (window.innerWidth)

winWidth = window.innerWidth;

else if ((document.body) && (document.body.clientWidth))

winWidth = document.body.clientWidth;

if (window.innerHeight)

winHeight = window.innerHeight;

else if ((document.body) && (document.body.clientHeight))

winHeight = document.body.clientHeight;

if (document.documentElement && document.documentElement.clientHeight &&

document.documentElement.clientWidth)

{

winHeight = document.documentElement.clientHeight;

winWidth = document.documentElement.clientWidth;

}

img.width= winHeight;

img.width= winWidth;

}

</script>

</body>

</html>

Please remove the control style if it is present.

http://forums.asp.net/p/1228180/2212987.aspx

1.9 How to clear the session when the user closes a window [top]

Use the code,

function window.onbeforeunload()

{

var xmlHttp;

try

{

// Firefox, Opera 8.0+, Safari

xmlHttp=new XMLHttpRequest();

}

catch (e)

{

// Internet Explorer

try

{

xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");

}

catch (e)

{

try

{

xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");

}

catch (e)

{

alert("Your browser does not support AJAX!");

return false;

}

if(event.clientX>document.body.clientWidth&&event.clientY<0||event.altKey)

{

xmlhttp.open("GET","exit.aspx",false);

xmlhttp.send();

}

</script>

http://forums.asp.net/p/1237752/2255401.aspx

2. Ways to pass data between pages

2.1 How to use cookies [top]

Create a page named page1.aspx, and then drag a button and a TextBox onto the page. Double click the button and then add the following code:

protected void Button1_Click(object sender, EventArgs e)

{

HttpCookie cookie = new HttpCookie("UserName");

cookie.Value = TextBox1.Text;

cookie.Expires = DateTime.Now.AddDays(1);

Response.Cookies.Add(cookie);

Response.Redirect("Page2.aspx");

}

page1.aspx,

<div>

<asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Button" />

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

</div>

On page2.aspx, double click the form and put the following code in it:

protected void Page_Load(object sender, EventArgs e)

{

if (Request.Cookies["UserName"] != null)

Response.Write(Request.Cookies["UserName"].Value);

}

http://forums.asp.net/t/1223291.aspx

Asp.Net Cookies Overview

How to: Read a Cookie

How to: Delete a Cookie

ASP.NET State Management Overview

ASP.NET State Management Recommendations

2.2 How to use QueryString [top]

private void Button1_Click (object sender, System.EventArgs e)

{

string url;

url="anotherwebform.aspx?name=" +

TextBox1.Text + "&email=" + TextBox2.Text;

Response.Redirect(url);

}

Destination web form

private void Page_Load (object sender, System.EventArgs e)

{

Label1.Text=Request.QueryString["name"];

Label2.Text=Request.QueryString["email"];

}

http://forums.asp.net/p/1223291/2191155.aspx

ASP.NET State Management Overview

ASP.NET State Management Recommendations

2.3 How to use Session [top]

private void Button1_Click(object sender, System.EventArgs e)

{

//Drag TextBox1 and TextBox2 onto a web form

Session["name"]=TextBox1.Text;

Session["email"]=TextBox2.Text;

Server.Transfer("anotherwebform.aspx");

}

Destination web form

private void Page_Load(object sender, System.EventArgs e)

{

Label1.Text=Session["name"].ToString();

Label2.Text=Session["email"].ToString();

Session.Remove("name");

Session.Remove("email");

}

http://forums.asp.net/p/1255625/2333723.aspx

How to: Read Values from Session State

How to: Save Values in Session State

HttpSessionState Class

ASP.NET State Management Overview

ASP.NET State Management Recommendations

2.4 How to use Context [top]

//Page1.aspx stores value in context before transferring

Context.Items("UserName") = txtName.Text;

Server.Transfer("Page2.aspx");

//Page2.aspx retrieves the value from Page1’s context

string sName;

sName = Context.Items("UserName").ToString;

Response.Write("Your name is " + sName);

http://forums.asp.net/t/1238286.aspx

HttpContext Class

ASP.NET State Management Overview

ASP.NET State Management Recommendations

2.5 How to use PreviousPage [top]

FirstForm.aspx

<asp:Button id="buttonPassValue" runat="server" Text="Button" PostBackUrl="~/SecondForm.aspx">

</asp:Button>

SecondForm.aspx.cs

TextBox1.Text = Request.Form["TextBox1"].ToString();

Or SecondForm.aspx.cs

TextBox textBoxTemp = (TextBox) PreviousPage.FindControl("TextBox1");

TextBox1.Text = textBoxTemp.Text;

As you’ve noticed, this is a simple and clean implementation of passing values between pages.

http://forums.asp.net/p/1048041/1474374.aspx

Page.PreviousPage Property

How to: Pass Values Between ASP.NET Web Pages

2.6 How to use Submit Form [top]

page1.aspx,

<%@ Page Language="C#" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

</script>

<head>

function CopyTextToHiddenField()

{

var textbox1Value = document.getElementById("<%=TextBox1.ClientID%>").value;

document.forms[1].document.getElementById("Hidden1").value = textbox1Value;

}

</script>

</head>

<body>

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

</form>

</form>

</body>

</html>

page2.aspx,

<%@ Page Language="C#" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

protected void Page_Load(object sender, EventArgs e)

{

Response.Write(Request.Form["Hidden1"]);

}

</script>

</head>

<body>

<div>

</div>

</form>

</body>

</html>

http://forums.asp.net/p/1257184/2339923.aspx

2.7 How to use Server.Transfer [top]

page1.aspx,

<%@ Page Language="C#" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

protected void Button_Click(object sender, EventArgs e)

{

Server.Transfer("page2.aspx", true);

}

</script>

</head>

<body>

<div>

<asp:Button ID="Button1" runat="server" Text="Button" OnClick="Button_Click" />

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

</div>

</form>

</body>

</html>

page2.aspx,

<%@ Page Language="C#" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

protected void Page_Load(object sender, EventArgs e)

{

Response.Write(Request.Form["TextBox1"]);

}

</script>

</head>

<body>

<div>

</div>

</form>

</body>

</html>

http://forums.asp.net/p/1262144/2362078.aspx

http://msdn.microsoft.com/en-us/library/6c3yckfw.aspx

http://dotnetslackers.com/community/blogs/haissam/archive/2007/11/26/ways-to-pass-data-between-webforms.aspx

Cross-Page Posting in ASP.NET Web Pages

How to: Determine How ASP.NET Web Pages Were Invoked

3. File Upload

3.1 How to upload a file [top]

if (FileUpLoad1.HasFile)

{

FileUpLoad1.SaveAs(Server.MapPath("upload")+ "\\" + FileUpLoad1.FileName);

}

FileUpload Web Server Control Overview FileUpload Class

3.2 How to upload multiple files at once [top]

Please check the following article, in the article, Haissam Abdul Malak will explain how to upload multiple files in an organized way using HtmlInputFile control.

http://forums.asp.net/t/1263738.aspx

http://aspalliance.com/1221_CodeSnip_Uploading_Multiple_Files_At_Once.all

3.3 Why upload fails when using an ASP.NET FileUpload control to upload large files [top]

For security reasons, ASP.NET is limited in terms of an uploaded file size. The default maximum file size is 4 MB but this can be changed by modifying the MaxRequestLength attribute of Machine.config's <httpRuntime> element.

http://forums.asp.net/t/1074332.aspx

http://forums.asp.net/p/1106754/1696069.aspx#1696069

3.4 How to upload an image files only [top]

See the code,

Fileupload.aspx:

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

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<title>Upload Image Demo</title>

</head>

<body>

<div>

<asp:Image ID="Image1" runat="server" />

<asp:FileUpload ID="FileUpload1" runat="server" />

<asp:Button ID="btnSubmit" runat="server" Text="Submit" OnClick="btnSubmit_Click" />

</div>

</form>

</body>

</html>

Fileupload.aspx.cs:

using System;

using System.Collections;

using System.Configuration;

using System.Data;

using System.Linq;

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.Xml.Linq;

public partial class FileuploadDemo : System.Web.UI.Page

{

protected void btnSubmit_Click(object sender, EventArgs e)

{

string fileFullname = this.FileUpload1.PostedFile.FileName;

string dataName = DateTime.Now.ToString("yyyy-MM-dd hh-mm-ss");

string fileName = fileFullname.Substring(fileFullname.LastIndexOf("\\") + 1);

string type = fileFullname.Substring(fileFullname.LastIndexOf(".") + 1);

if (FileUpload1.PostedFile.ContentType.ToUpper().IndexOf("IMAGE") > -1)

{

System.Drawing.Image img = System.Drawing.Image.FromStream(FileUpload1.PostedFile.InputStream);

int Width = img.Width;

int Height = img.Height;

if (Width > 1000 || Height > 1000 || FileUpload1.PostedFile.ContentLength > 1024 * 1024 * 200)

{

this.ClientScript.RegisterStartupScript(this.GetType(), "Startup",
"<script language='javascript'>alert('The image size is too large!');</script>");

}

else

{

if (type == "jpg" || type == "gif" || type == "bmp" || type == "JPG" || type == "GIF")

{

string ImagePath = "images/";

string sPath = Server.MapPath(ImagePath) + dataName + fileName;

string imgPath = ImagePath + dataName + fileName;

this.FileUpload1.PostedFile.SaveAs(sPath);

this.ClientScript.RegisterStartupScript(this.GetType(),
"Startup", "<script language='javascript'>alert('Success!');</script>");

this.Image1.ImageUrl = imgPath;

this.btnSubmit.Enabled = false;

this.btnSubmit.Text = "Success!";

this.btnSubmit.Enabled = true;

}

else

{

this.ClientScript.RegisterStartupScript(this.GetType(), "Startup",
"<script language='javascript'>alert('File type is not right!');</script>");

}

else

{

this.ClientScript.RegisterStartupScript(this.GetType(), "Startup",
"<script language='javascript'>alert('The uploaded file is not a image file!');</script>");

}

http://forums.asp.net/p/1051895/2171502.aspx

3.5 How to get a File Upload control work with an UpdatePanel [top]

The FileUpload control does not work with asynchronous post backs and therefore does not work from within an AJAX UpdatePanel.

The trick to make the FileUpload to work within an Ajax UpdatePanel is to setup a PostBackTrigger in the UpdatePanel control.

Demo code:

<asp:UpdatePanel ID="UpdatePanel1" runat="server">

<asp:PostBackTrigger ControlID ="Button1" />

</Triggers>

<asp:FileUpload ID ="fileupload1" runat ="server" /><br />

<asp:Button ID ="Button1" runat ="server" Text ="Upload" OnClick="Button1_Click" /><br />

<asp:Label ID ="Lable1" runat ="server" Text =""></asp:Label>

<asp:LinkButton ID ="LinkButton1" runat="server" Text ="Click Here" OnClick="LinkButton1_Click"></asp:LinkButton>

</ContentTemplate>

</asp:UpdatePanel>

http://forums.asp.net/p/1105208/1689084.aspx

4. Calendar

4.1 How to change the culture settings for a Calendar [top]

In calendar.aspx.cs:

private void Page_Load(object sender, System.EventArgs e)

{

System.Globalization.CultureInfo culture = System.Globalization.CultureInfo.CreateSpecificCulture("ens");

System.Threading.Thread.CurrentThread.CurrentCulture = culture;
System.Threading.Thread.CurrentThread.CurrentUICulture = culture;

}

http://forums.asp.net/t/1133896.aspx

4.2 How to select multiple non-sequential dates at Code-Behind [top]

Invoke the member function ‘Add’ of the control's SelectedDates collection. You can add dates in any sequence, because the collection will automatically arrange them in order for you.

protected void Calendar1_SelectionChanged(object sender, EventArgs e)

{

Calendar1.SelectedDates.Clear();

Calendar1.SelectedDates.Add(new DateTime(2008, 8, 1));

Calendar1.SelectedDates.Add(new DateTime(2008, 8, 7));

Calendar1.SelectedDates.Add(new DateTime(2008, 8, 15));

}

http://forums.asp.net/t/1260917.aspx

4.3 How to disable some dates in Calendar control [top]

protected void Calendar1_DayRender(object sender, DayRenderEventArgs e)

{

string date="02/01/2008";

DateTime dt = DateTime.Parse(date);

if (e.Day.Date == dt)

e.Day.IsSelectable = false;

}

http://forums.asp.net/t/1230073.aspx

How to: Customize Individual Days in a Calendar Web Server Control

4.4 How to extend Calendar control for Server-Side validation [top]

Refer to:

http://support.microsoft.com/default.aspx?scid=kb;en-us;310145

4.5 How to set ToolTips and links in Calendar control’s DayRender event [top]

protected void Calendar1_DayRender(object sender, DayRenderEventArgs e)

{

e.Cell.Controls.Clear();

HyperLink link = new HyperLink();

link.Text = e.Day.Date.Day;

link.ToolTip = "anything you want here!";

link.NavigateUrl = url;

e.Cell.Controls.Add(link);

}

http://forums.asp.net/p/1036174/1800067.aspx

4.6 How to give some dates different appearances [top]

We can do this with the following code:

protected void Calendar1_DayRender(object sender, DayRenderEventArgs e)

{

if (e.Day.Date.Month == 2 && e.Day.Date.Day == 25)

{

e.Cell.BackColor = System.Drawing.Color.Yellow;

}

if (e.Day.Date.DayOfWeek == DayOfWeek.Friday || e.Day.Date.DayOfWeek == DayOfWeek.Saturday)

{

e.Cell.Controls.Clear();

e.Cell.Text = "today isweekend";

}

http://forums.asp.net/p/1036174/1800067.aspx

How to: Customize Individual Days in a Calendar Web Server Control

How to: Format Calendar Web Server Control Elements Using Styles

5. List controls

5.1 How to enable ASP.NET DropDownList with OptionGroup support [top]

We can override the function of DropDownList, and add the additional property for it.

Here are some good articles about it.

Refer to:

http://www.codeproject.com/KB/custom-controls/xlist.aspx

http://www.codeproject.com/KB/custom-controls/DropDownListOptionGroup.aspx

5.2 How to disable an item in DropDownList [top]

<asp:DropDownList ID="DropDownList1" runat ="server" Width="235px" AutoPostBack="False">

<asp:ListItem>1</asp:ListItem>

<asp:ListItem>2</asp:ListItem>

<asp:ListItem>3</asp:ListItem>

<asp:ListItem>4</asp:ListItem>

</asp:DropDownList>

protected void Page_Load(object sender, EventArgs e)

{

DropDownList1.Attributes.Add("onchange", "change();");

}

function change()

{

var dd=document.getElementById ('<%=DropDownList1.ClientID %>');

var value=dd.options[dd.selectedIndex].value;

if(value!="2") //supose you want to disable the item numbered 2

{

setTimeout("__doPostBack('DropDownList1','')", 0);

}

</script>

http://forums.asp.net/p/1041568/1451492.aspx

5.3 How to hold the selected value for a DropDownList [top]

You should place your data binding code for the dropdownlist in the !page.Ispostback block.

the !postback block will ensure it will only be filled once during post backs.

if(!Page.IsPostBack)

{

//bind template drop down here

}

http://forums.asp.net/p/1251081/2312321.aspx

6. User control

6.1 How to add a new property to UserControl [top]

You can setup new properties inside the class definition of the user control at its .ascx.cs file.Example:

ascx file,

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="WebUserControl.ascx.cs" Inherits="WebUserControl" %>

<asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>

<asp:Calendar ID="Calendar1" runat="server"></asp:Calendar>

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

ascx.cs file,

public partial class WebUserControl : System.Web.UI.UserControl

{

String text2 = String.Empty;

public String Text

{

get

{

return Label1 .Text ;

}

set

{

Label1 .Text = value;

}

public String Text2

{

get

{

return text2;

}

set

{

text2 = value;

}

protected void Page_Load(object sender, EventArgs e)

{

TextBox1.Text = text2;

}

aspx file

<%@ Register src="WebUserControl.ascx" mce_src="WebUserControl.ascx" TagName="WebUserControl" TagPrefix="uc1" %>

<uc1:WebUserControl id="WebUserControl1" runat="server" Text="Hello world" Text2="Hello world.">

</uc1:WebUserControl>

http://forums.asp.net/t/349580.aspx

6.2 How to access a dynamically created UserControl [top]

You can use FindControl method to get a reference to the target child control of your user control and then use it just like any other controls.

Example:

UC.ascx,

<%@ Control Language="C#" ClassName="UC" %>

</script>

<asp:TextBox ID="txtName" runat="server"></asp:TextBox>

Page.aspx:

<%@ Page Language="C#" %>

<%@ Register src="UC.ascx" tagname="UC" tagprefix="uc1" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

protected void btnLoad_Click(object sender, EventArgs e)

{

UC uc = new UC();

uc.LoadControl("~/uc/UC.ascx");

uc.ID = "MyUC";

form1.Controls.Add(uc);

(form1.FindControl("MyUC").FindControl("txtName") as TextBox).Text = "ASP.NET";

}

</script>

<title>User Control Demo</title>

</head>

<body>

<div>

<asp:Button ID="btnLoad" runat="server" Text="Loading user control ..."

onclick="btnLoad_Click" />

</div>

</form>

</body>

</html>

6.3 How to access a control inside a UserControl [top]

Assume there is a user control called UC and there is only a TextBox control inside it. Now drag this user control into a web page, you can use the following code to visit the TextBox control.

((TextBox)UC1.FindControl("TextBox1")).Text = "demo";

To known the basic principle, please refer to INamingContainer:

http://msdn.microsoft.com/en-us/library/system.web.ui.inamingcontainer.aspx

7. Dynamic controls

7.1 How to create a dynamic control [top]

We can create the dynamic control in the Page_Init() event or Page_Load() event,

protected void Page_Load(object sender, EventArgs e)

{

TextBox dynamicTextBox = new TextBox();

dynamicTextBox.ID = "DynamicTextBox";

dynamicTextBox.AutoPostBack = true;

dynamicTextBox.Text = "InitData";

dynamicTextBox.TextChanged += new EventHandler(dynamicTextBox_TextChanged);

this.Form.Controls.Add(dynamicTextBox);

}

void dynamicTextBox_TextChanged(object sender, EventArgs e)

{

Response.Write("hello");

}

http://forums.asp.net/t/1152363.aspx

7.2 How to access a user entered value in a dynamic created TextBox control [top]

a. Get the value from the form's POST data. Here is the code:

if(Request.Form["dynamicTextBox"] != null)

selectedValue = Request.Form["dynamicTextBox"].ToString();

b. Get the value by finding the control at the webpage.

TextBox txt=this.form1.FindControl("dynamicTextBox") as TextBox;

See the whole demo code,

<%@ Page Language="C#" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

public string Res = string.Empty;

protected void Page_Load(object sender, EventArgs e)

{

TextBox dynamicTextBox = new TextBox();

dynamicTextBox.ID = "dynamicTextBox";

form1.Controls.Add(dynamicTextBox);

}

protected void btnForm_Click(object sender, EventArgs e)

{

lblMsg.Text += "<br /> Form way:";

if (Request.Form["dynamicTextBox"] != null)

Res = Request.Form["dynamicTextBox"].ToString();

lblMsg.Text += Res;

}

protected void btnFindControl_Click(object sender, EventArgs e)

{

lblMsg.Text += "<br /> FindControl way: ";

TextBox dynamicTextBox = this.form1.FindControl("dynamicTextBox") as TextBox;

Res = dynamicTextBox.Text;

lblMsg.Text += Res;

}

</script>

</head>

<body>

<div>

<asp:Label ID="lblMsg" runat="server" Text=""></asp:Label>

<asp:Button ID="btnForm" runat="server" Text="Form Way" OnClick="btnForm_Click" />

<asp:Button ID="btnFindControl" runat="server" Text="FindControl Way" OnClick="btnFindControl_Click" />

</div>

</form>

</body>

</html>

http://forums.asp.net/p/1119972/1745762.aspx

7.3 Dynamic controls accessed by JavaScript [top]

Reference the ClientID property (or UniqueID) of the control in the Javascript.

protected void Page_Load(object sender, EventArgs e)

{

Button btn= new Button();

btn.ID = "btn5";

btn.Attributes.Add("runat", "server");

btn.Attributes.Add("onclick", "pop('" + btn.ClientID + "')");

btn.Text = "Test";

this.form1.Controls.Add(btn);

}

function pop(InputBoxID)

{

var InputControl = document.getElementById(InputBoxID);

alert(InputControl.value);

}

Or,

Use the following method.

btn.Attributes.Add("onclick", "pop(this)");

function pop(InputBox)

{

alert(InputBox.value);

}

http://forums.asp.net/p/1239593/2260331.aspx#2260331

7.4 How to retain all added server controls dynamically after post back [top]

You should recreate these dynamic control at Page_load or Page_init() function everytime.

protected void Page_Load(object sender, EventArgs e)

{

//recreate these dynamic control.

}

http://forums.asp.net/p/1242809/2280514.aspx

7.5 Why dynamically created controls disappear after a post back [top]

The dynamic button must be re-created on each post back, so remove the if(!Page.IsPostBack). It's probably better if you create the controls at the Page_Init event.

http://forums.asp.net/p/1080863/1598618.aspx

8. Style

8.1 How to use with Code-Behind [top]

Label1.Attributes.Add("style", "background-color:Red");

8.2 How to use with JavaScript [top]

document.getElementById("Label1").style.backgroundColor = "Red";

8.3 How to remove a space [top]

Add the following code inside of the “head” tag,

body

{

padding: 0px;

margin: 0px;

}

</style>

8.4 How to use with html [top]

Note: CSS is valuable

Linked style sheet usually lives in <head> tag, but there is no need to worry if it is put inside <body> tag. As well, <head> tag must have a runat=”server” attribute.

http://forums.asp.net/p/1197909/2076464.aspx

8.5 How to set an image as Button’s background [top]

http://forums.asp.net/t/299555.aspx

8.6 How to color items in ListBox [top]

Demo code:

.optred{background-color:red;}

.optblue{background-color:blue;}

</style>

protected void Page_PreRender(object sender, EventArgs e)

{

bool flag=false;

foreach (ListItem li in ListBox1.Items)

{

if (flag)

{

li.Attributes.Add("class", "optred");

flag = false;

}

else

{

li.Attributes.Add("class", "optblue");

flag = true;

}

Please refer to:

http://www.codeproject.com/KB/webforms/ColorListBox.aspx

9. Print

9.1 How to print a part of a web page with CSS [top]

CSS CODE:

.Noprint

{

display: none;

}

.Print

{

page-break-after: always;

}

</style>

HTML CODE:

I am not print;

</div>

I will print;

</div>

http://forums.asp.net/t/981539.aspx

9.2 How to print a part of a web page with JavaScript (1) [top]

JavaScript CODE:

function doPrint() {

bdhtml=window.document.body.innerHTML;

sprnstr="";

eprnstr="";

prnhtml=bdhtml.substr(bdhtml.indexOf(sprnstr)+17);

prnhtml=prnhtml.substring(0,prnhtml.indexOf(eprnstr));

window.document.body.innerHTML=prnhtml;

window.print();

}

</script>

HTML CODE:

This area will print!

<br />

I will not print?

http://forums.asp.net/p/1234564/2256428.aspx

9.3 How to print a part of a web page with JavaScript (2) [top]

JavaScript CODE:

function printdiv(divID)

{

var headstr = "<html><head><title></title></head><body>";

var footstr = "</body>";

var newstr = document.all.item(divID).innerHTML;

var oldstr = document.body.innerHTML;

document.body.innerHTML = headstr+newstr+footstr;

window.print();

document.body.innerHTML = oldstr;

return false;

}

</script>

HTML CODE:

The Div content which you want to print</h1>

</div>

http://forums.asp.net/t/1263912.aspx

10. Mail

10.1 What classes are needed to send e-mails in ASP.NET [top]

Class MailMessage and SmtpMail are used to send emails from an ASP.NET application. MailMessage and SmtpMail are from System.Web.Mail namespace of .NET Framework 1.1 Class Library. Also, you can use System.Net.Mail instead of System.Web.Mail if you have .NET Framework version 2.0 installed.

10.2 How to send emails by using System.Net.Mail [top]

CODE-BEHIND:

MailMessage message = new MailMessage();

message.From = new MailAddress("fromusername@DomainName");

message.To.Add(new MailAddress("tousername@DomainName"));

message.CC.Add(new MailAddress("ccusername@DomainName"));

message.Subject = "Subject";

message.Body = "Content";

SmtpClient client = new SmtpClient();

client.Send(message);

web.config:

<system.net>

</smtp>

</mailSettings>

</system.net>

http://forums.asp.net/t/971802.aspx

10.3 How to configure a SMTP Server [top]

Taking the IIS as an example, please review the following links:

http://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/56c94d38-b10f-4a1b-a1cd-3714387a042a.mspx?mfr=true

http://www.codeproject.com/KB/winsdk/ConfigServerSmtp.aspx

10.4 How to send an email with Gmail server [top]

Please read FAQ “How to send email by using System.Net.Mail?” first. Please note that you need to be aware of the following points while configuring the following settings:

· SMTP server name

· Port number

· SSL authentication

Gmail SMTP server name is “smpt.gmail.com”;

Gmail port is 465, not the default port 25;

The SSL authentication should be set to true;

So the secret of sending mails successfully with Gmail is: port 465, server name “smtp.gmail.com” and SSL = true.

http://forums.asp.net/p/1167140/1944223.aspx

http://forums.asp.net/p/1234241/2235990.aspx

官方地址：http://forums.asp.net/t/1360420.aspx

posted @ 2009-02-12 11:54 海洋——海纳百川,有容乃大. 阅读(2041) 评论(6) 编辑收藏举报

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【原】 Web Forums FAQ【JavaScript，User control，Dynamic controls，Mail等10个方面】

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