一个复合控件的简单例子

 CompositeLogin.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace myControl
...{
    [DefaultProperty("Text")]
    [ToolboxData("<{0}:CompositeLogin runat='server'></{0}:CompositeLogin>")]
    public class CompositeLogin : WebControl,INamingContainer
    ...{
    Text attribute#region Text attribute
        [Bindable(true)]
        [Category("Appearance")]
        [DefaultValue("")]
        [Localizable(true)]
        public string Text
        ...{
            get
            ...{
                String s = (String)ViewState["Text"];
                return ((s == null) ? String.Empty : s);
            }

            set
            ...{
                ViewState["Text"] = value;
            }
        }
    #endregion
        private TextBox _nameTextbox;
        private TextBox _passwordTextbox;
        private Label _nameLabel;
        private Label _passwordLabel;
        private Button _button;
        private RequiredFieldValidator _namevalidator;
        private RequiredFieldValidator _passwordValidator;

        private static readonly object EventLogin = new object();

        Override Properties#region Override Properties
        public override ControlCollection Controls
        ...{
            get
            ...{
                EnsureChildControls();
                return base.Controls;
            }
        }
        #endregion Override Properties

        Properties delegate to child controls#region Properties delegate to child controls
        public string ButtonText
        ...{
            get ...{
                EnsureChildControls();
                return _button.Text;
            }
            set ...{
                EnsureChildControls();
                this._button.Text = value;
            }
        }

        public string Name
        ...{
            get ...{
                EnsureChildControls();
                return this._nameTextbox.Text;
            }
            set ...{
                this._nameTextbox.Text = value;
            }
        }

        public string NameErrorMessage
        ...{
            get ...{
                EnsureChildControls();
                return this._namevalidator.ErrorMessage;
            }
            set ...{
                EnsureChildControls();
                _namevalidator.ErrorMessage = value;
                _namevalidator.ToolTip = value;
            }
        }

        public string NameLabel
        ...{
            get ...{
                EnsureChildControls();
                return this._nameLabel.Text;
            }
            set ...{
                EnsureChildControls();
                this._nameLabel.Text = value;
            }
        }

        public string Password
        ...{
            get ...{
                EnsureChildControls();
                return this._passwordTextbox.Text;
            }
        }

        public string PasswordErrorMessage
        ...{
            get ...{
                EnsureChildControls();
                return this._passwordValidator.ErrorMessage;
            }
            set ...{
                EnsureChildControls();
                this._passwordValidator.ErrorMessage = value;
                this._passwordValidator.ToolTip = value;
            }
        }

        public string PasswordLabel
        ...{
            get ...{
                EnsureChildControls();
                return this._passwordLabel.Text;
            }
            set ...{
                EnsureChildControls();
                this._passwordLabel.Text = value;
            }
        }
        #endregion

        Event#region Event
        public event EventHandler Login
        ...{
            add ...{
                Events.AddHandler(EventLogin, value);
            }
            remove ...{
                Events.RemoveHandler(EventLogin, value);
            }
        }

        protected virtual void OnLogion(EventArgs e)
        ...{
            EventHandler onlogionEvent = (EventHandler)Events[EventLogin];
            if (onlogionEvent != null)
            ...{
                onlogionEvent(this, e);
            }
        }
        //???????????????????????
        protected override bool OnBubbleEvent(object source, EventArgs args)
        ...{
            bool handled = false;
            if (args is CommandEventArgs) ...{ 
                CommandEventArgs ce=(CommandEventArgs)args;
                if(ce.CommandName=="Logon")...{
                    OnLogion(EventArgs.Empty);
                    handled=true;
                }
            }
            return handled;
        }
        //???????????????????????
        #endregion

        Override CreateChildControls#region Override CreateChildControls
        protected override void CreateChildControls()
        ...{
            base.CreateChildControls();
            Controls.Clear();
            _nameLabel = new Label();
            _passwordLabel = new Label();

            _nameTextbox = new TextBox();
            _passwordTextbox = new TextBox();
            _nameTextbox.ID = "nametextbox";
            _passwordTextbox.ID = "pswtextbox";
            _passwordTextbox.TextMode = TextBoxMode.Password;

            _passwordValidator = new RequiredFieldValidator();
            _namevalidator = new RequiredFieldValidator();
            _passwordValidator.ID = "val1";
            _passwordValidator.ControlToValidate = _passwordTextbox.ID;
            _passwordValidator.Text = "*";
            _passwordValidator.Display = ValidatorDisplay.Static;

            _namevalidator.ID = "val2";
            _namevalidator.ControlToValidate = _nameTextbox.ID;
            _namevalidator.Text = "*";
            _namevalidator.Display = ValidatorDisplay.Static;


            _button = new Button();
            _button.ID = "button1";
            _button.CommandName = "Logon";

            this.Controls.Add(_nameLabel);
            this.Controls.Add(_passwordLabel);
            this.Controls.Add(_nameTextbox);
            this.Controls.Add(_passwordTextbox);
            this.Controls.Add(_namevalidator);
            this.Controls.Add(_passwordValidator);
            this.Controls.Add(_button);
        }
        #endregion
        Override Render#region Override Render
        protected override void Render(HtmlTextWriter writer)
        ...{
            //base.Render(writer);
            AddAttributesToRender(writer);
            writer.AddAttribute(HtmlTextWriterAttribute.Cellpadding, "1", false);
            writer.RenderBeginTag(HtmlTextWriterTag.Table);
            writer.RenderBeginTag(HtmlTextWriterTag.Tr);
                writer.RenderBeginTag(HtmlTextWriterTag.Td);
                _nameLabel.RenderControl(writer);   //label name
                writer.RenderEndTag();
                writer.RenderBeginTag(HtmlTextWriterTag.Td);
                _nameTextbox.RenderControl(writer);     //textbox name
                writer.RenderEndTag();
                writer.RenderBeginTag(HtmlTextWriterTag.Td);
                _namevalidator.RenderControl(writer);   //*
                writer.RenderEndTag();
            writer.RenderEndTag();

            writer.RenderBeginTag(HtmlTextWriterTag.Tr);
                writer.RenderBeginTag(HtmlTextWriterTag.Td);
                _passwordLabel.RenderControl(writer);   //label psw
                writer.RenderEndTag();
                writer.RenderBeginTag(HtmlTextWriterTag.Td);
                _passwordTextbox.RenderControl(writer); //textbox psw  
                writer.RenderEndTag();
                writer.RenderBeginTag(HtmlTextWriterTag.Td);
                _passwordValidator.RenderControl(writer);   //*
                writer.RenderEndTag();
            writer.RenderEndTag();

            writer.RenderBeginTag(HtmlTextWriterTag.Tr);
                writer.AddAttribute(HtmlTextWriterAttribute.Colspan, "2");
                writer.AddAttribute(HtmlTextWriterAttribute.Align, "right");
                writer.RenderBeginTag(HtmlTextWriterTag.Td);
                _button.RenderControl(writer);  //button submit
                writer.RenderEndTag();
            writer.RenderEndTag();
            writer.RenderEndTag();
        }
        #endregion
      
    }
}

样式如下：

//？？？？？？？？？？内的方法不知道什么作用？？