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This article mainly introduces what are the basic knowledge points of ASP.NET control development, the article is very detailed, has a certain reference value, interested friends must read it!

Summary of the basics of ASP.NET control development 1.1 where to inherit

Custom controls typically come from the following base classes (data controls are not included here)

1. Control class (the base class of all server controls is a relatively low-level class. If the function of the control is simple and does not require much, you can directly inherit this class.)

II. WebControl class (base class of standard controls, inheriting this class, you can inherit its rich public properties, if the controls in standard controls do not have the controls you need, you can inherit this class)

III. CompositeControl class (2.0new class, which inherits from the WebControl class, if you need to make composite controls, please start by inheriting this class)

four。 Inherit directly from the built-in control (we know that the wheel only needs to be invented once, and if your requirements are similar to the built-in, please consider doing so)

Summary of ASP.NET Control Development Foundation 1.2 rendering controls

The Render method of the Control class is the basic rendering method, and the RenderContent method is on top of the Render method, which adds a label to the control. I think the RenderContent method is prepared for properties in the WebControl class. The basic methods continue to be understood deeply.

Summary of the basics of ASP.NET control development 1.3 interact with users

Pure rendering of controls is not enough, we need to pass data, which inevitably leads us to understand custom control event handling

Summary of ASP.NET Control Development Foundation 1.4 contact Properties

The attribute is relatively simple and easy to understand, but it is more troublesome. When there are too many properties of the control, it is easy to mess up, so we recognize the metadata and classify the properties, as shown in the following figure

In order to make it clearer and classify the attributes, we use another method to define a variety of attributes of the same type in a large attribute, which is called a complex attribute, as shown in the following figure

There are enough attributes, it doesn't matter, we also know that each type of property may be different, and after rendering is rendered in the form of a string, the simple property .net has handled the conversion for you, and when you customize the complex property, you need to define a type converter for the complex properties you define.

Another way to use attributes is to use them as collection properties. It can be said that it is a complex control with special words, and this can provide some list controls to use properties (see article 10).

Summary of ASP.NET Control Development Foundation 1.5 Control Styles

How can controls be short of style? we naturally need it, and here we recognize the WebControl class again. Of course, I also learned about the style class and its subclasses.

As long as you know a few of these methods, you can customize the control style

Summary of the Development Foundation of ASP.NET controls 1.6 Composite controls

The function of the composite control is often more powerful, it uses the existing controls to assemble into a new control, in this process, we learned to define events and styles in the composite control.

Summary of ASP.NET Control Development Foundation 1.7 View State

A topic that has to be discussed.

Generally, the properties we define for controls are saved in the form of view state, but complex property definitions and control style definitions require you to know how to customize view state.

We also discussed how to add client functionality to the control and define a generator for the control. Well, the summary has finally come to an end. The above has been written twice. It is painful to lose the data after being saved.

Let's share some tips, which you may already know. In order to learn better in the future, I will change all named controls to AspDemo.CustomComponents.

The source code of this download includes all the sample code of 1-16 articles. If there are any mistakes, please point out.

Summary and supplement to the basics of ASP.NET control development:

Summary and supplement to the foundation of ASP.NET control development. Use of embedded resources

1. Embedded control icon

Built-in controls all have their own icons, and many people also like to make an icon for their own controls, so how to do that?

We only need to use ToolboxBitmap metadata, you need to know its constructor, the usage is as follows

Namespace AspDemo.CustomComponents {[ToolboxBitmap (typeof (ImageControl), "Resources.Image.bmp")] public class ImageControl: WebControl {}

Note:

(1) the location of the icon is located in the root directory of your default namespace, and specify the location of the icon in the way of dot syntax (that is, the icon path is / Resources), otherwise, the named control of your control type is the root directory (that is, the icon path is CustomComponents/Resources). You can try it.

(2) indicate that the icon file is an embedded resource in the properties panel, as shown in the following figure

two。 Embed other resource files

Remember that we made a control needs a js file, when we need to use this control, then we also need to use js file, so it is very bad for others to use, we can use js file as an embedded resource to solve this problem. The following example is from MSDN, just to let you know how to use it.

[assembly: WebResource ("AspDemo.CustomComponents.Resources.AspDemo.CustomComponents.ResourceLabel.image1.jpg", "image/jpeg")] [assembly: WebResource ("AspDemo.CustomComponents.Resources.AspDemo.CustomComponents.ResourceLabel.help.htm", "text/html", PerformSubstitution = true)] namespace AspDemo.CustomComponents {public class ResourceLabel: Control {protected override void CreateChildControls () {/ / Create a new Image control. Image _ img = new Image (); / / get resource file reference _ img.ImageUrl = this.Page.ClientScript.GetWebResourceUrl (this.GetType (), "AspDemo.CustomComponents.Resources.AspDemo.CustomComponents.ResourceLabel.image1.jpg"); this.Controls.Add (_ img); / / Create a new Label control. Label _ lab = new Label (); _ lab.Text = "A composite control using the WebResourceAttribute class."; this.Controls.Add (_ lab); / / Create a new HtmlAnchor control linking to help.htm. HtmlAnchor a = new HtmlAnchor (); a.HRef = this.Page.ClientScript.GetWebResourceUrl (typeof (ResourceLabel), "AspDemo.CustomComponents.Resources.AspDemo.CustomComponents.ResourceLabel.help.htm"); a.InnerText = "help link"; this.Controls.Add (new LiteralControl ("< / br >")); this.Controls.Add (a);}}

Note:

(1) same as the second point above

(2) the path is based on the default namespace, and then the file path is obtained by dot syntax (AspDemo.CustomComponents is the namespace, Resources is the folder, AspDemo.CustomComponents.ResourceLabel.help.htm is the file name)

OK, it's done.

Summary and supplement to the basis of ASP.NET control development II. Persistent control state

The following is only part of the code (from MSDN), I believe there is already a lot of information, only to add

Protected override void OnInit (EventArgs e) {base.OnInit (e); Page.RegisterRequiresControlState (this);} protected override object SaveControlState () {object obj = base.SaveControlState (); if (indexValue! = 0) {if (obj! = null) {return new Pair (obj, indexValue);} else {return (indexValue) }} else {return obj;}} protected override void LoadControlState (object state) {if (state! = null) {Pair p = state as Pair; if (p! = null) {base.LoadControlState (p.First); indexValue = (int) p.Second } else {if (state is int) {indexValue = (int) state;} else {base.LoadControlState (state);}}

Summary and supplement to the foundation of ASP.NET control development. Client callback

ASP.NET Unleashed lists a separate chapter on the use of JavaScript in custom controls. I think you should read some examples. I feel good and easy to understand. And if you learn this, you can also understand several controls in AtlasControlToolkit, almost all of which use this technology.

Summary and supplement to the foundation of ASP.NET control development. Configuration file

(1) pre-define control labels and register controls in web.config, so that you can omit them on each page

Use the @ Register instruction

< pages > < controls > < add tagPrefix= "aspDemo" namespace= "AspDemo.CustomComponents" assembly= "AspDemo.CustomComponents" / > < / controls > < / pages >

(2) Control mapping

URL can be mapped, and so can controls, which we used when configuring the Ajax environment.

< pages > < tagMapping > < add tagType= "System.Web.UI.WebControls.RequiredFieldValidator" mappedTagType= "System.Web.UI.Compatibility.RequiredFieldValidator, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" / > < / pages >

five。 Hide controls on the toolbar

Let's talk about another little thing. When a defined control does not need to be displayed on the toolbar, you can use this metadata to hide the control.

[ToolboxItem (false)] public class ImageControl: WebControl {}

All right, I have finished this article. If there are any mistakes, please point out that the above is all based on experience.

These are all the contents of this article entitled "what are the basic knowledge points of ASP.NET control development?" Thank you for reading! Hope to share the content to help you, more related knowledge, welcome to follow the industry information channel!

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