I. Solution
Literal is most commonly used to dynamically add content to pages.
Ii. Background
The literal control represents one of the several options used to add content to a page. For static content, you can add tags to the page as HTML without using containers. However, to add content dynamically, you must add the content to the container. Typical containers include label controls, literal controls, panel controls, and placeholder controls.
The difference between the literal control and the label control is that the literal control does not add any HTML elements to the text. (The label control presents a span element .) Therefore, the literal control does not support any style attributes including position attributes. However, the literal control allows you to specify whether to encode the content.
The Panel and placeholder controls are rendered as DIV elements, which create discrete blocks on the page, which are different from the labels and literal controls for Embedded rendering.
Generally, you can use the literal control when you want text and controls to be directly displayed on the page without any additional markup.
Encode content in the literal control
The literal control supports the mode attribute, which is used to specify how the control handles the tags you have added. You can set the mode attribute to the following values:
· Transform. converts any tags added to the control to adapt to the protocol of the requesting browser. This setting is useful for rendering content to mobile devices that use other protocols other than HTML.
· Passthrough. Any tag added to the control will be displayed in the browser as is.
· Encode. The htmlencode method will be used to encode any tag added to the control. This will convert HTML encoding into its text representation. For example, the <B> tag is displayed as & lt; B & gt ;. Encoding is useful when you want the browser to display without interpreting the mark. Encoding is also useful for security and helps prevent malicious tags from being executed in browsers. This setting is recommended when displaying strings from untrusted sources.
3. How to: Add literal Web Server Control to the web form page
You can add literal web server controls to web forms pages when you want to set text programmatically without adding additional HTML tags. The literal control is useful when you want to dynamically add text to a page without adding any elements that do not belong to the dynamic text. For example, you can use the literal control to display the HTML that you read from a file or stream.
Note: If you want to display static text, you can use HTML to present it. The literal control is not required. Only when you need to dynamically change the serverCodeThe literal control is used.
1. Drag the literal control from the "standard" tab of the toolbox to the page.
2. Alternatively, set the mode attribute to transform, passthrough, or encode under the "behavior" category in the "properties" window. The mode attribute specifies how the control handles any tag added to it. The following example shows a simple web page that displays the title news at runtime. The body of the page (including the literal control) is similar to the following code.
<Body>
<Form runat = "server">
<H1> <asp: literal id = "headline" runat = Server
Mode = "passthrough"/>
</Form>
</Body>
3. Add the code to the page to set the text attribute of the control at runtime.
The following example shows how to set the text and encoding of the literal control programmatically. This page contains a set of radio buttons that allow users to select between the encoded text and the transmitted text.
Note: If you are setting the text attribute to text from untrusted sources, you must set the mode attribute of the control to encode so that the tag will not form an executable tag.
<% @ Page Language = "C #" %>
<SCRIPT runat = "server">
Protected void page_load (Object sender, eventargs E)
{
Literal1.text = "This <B> text </B> is inserted dynamically .";
If (radioencode. Checked = true)
{
Literal1.mode = literalmode. encode;
}
If (radiopassthrough. Checked = true)
{
Literal1.mode = literalmode. passthrough;
}
}
</SCRIPT>
</SCRIPT>
<HTML>
<Head runat = "server">
<Body>
<Form ID = "form1" runat = "server">
<Div>
<Br/>
<Asp: radiobutton
Id = "radioencode"
Runat = "server"
Groupname = "literalmode"
Checked = "true"
TEXT = "encode"
Autopostback = "true"/>
<Br/>
<Asp: radiobutton
Id = "radiopassthrough"
Runat = "server"
Groupname = "literalmode"
TEXT = "passthrough"
Autopostback = "true"/>
<Br/>
<Br/>
<Asp: literal id = "literal1" runat = "server"> </ASP: literal> & nbsp; </div>
</Form>
</Body>
</Html>
Iv. Literal class
Retain the position where static text is displayed on the webpage.
Use the system. Web. UI. webcontrols. literal control to retain the position of text displayed on the webpage. The literal control is similar to the label control, but the literal control cannot apply a style to the displayed text. You can control the text displayed in the control programmatically by setting the text attribute.
Warning: This control can be used to display user input, which may contain malicious client scripts. In the ApplicationProgramBefore displaying any information sent from the client, check whether they contain executable scripts, SQL statements, or other code. ASP. NET provides the input request verification function to prevent users from entering scripts and HTML. The server control is also provided to verify user input.
Example
The following example shows how to use the literal control to display static text.
Note: The following example uses a single-file code model. If you copy it directly to a hidden code file, it may not work properly. This sample code must be copied to an empty text file with the. aspx extension.
<% @ Page Language = "C #" autoeventwireup = "true" %>
<! Doctype HTML public "-// W3C // dtd xhtml 1.0 transitional // en"
Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd>
<HTML>
<Head>
<Title> literal example </title>
<SCRIPT runat = "server">
Void buttonclick (Object sender, eventargs E)
{
Literal1.text = "Welcome to ASP. NET !! ";
}
</SCRIPT>
</Head>
<Body>
<Form ID = "form1" runat = "server">
<H3> literal example
<Asp: literal id = "literal1"
TEXT = "Hello world !! "
Runat = "server"/>
<Br/>
<Asp: button id = "button1"
TEXT = "Change literal text"
Onclick = "buttonclick"
Runat = "server"/>
</Form>
</Body>
</Html>
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