WEB自定义控件问题

Question

呈现控件时出错
发生了处理的异常
未将对像引用设置到对像的实例这是什么意思 呢      protected override void RenderContents(HtmlTextWriter output)
        {
           // output.Write(Text);
            //将要呈现的HTML属性添加到指定的System.Web.HtmlTextWriter中
           // AddAttributesToRender(output);
          //  output.AddAttribute(System.Web.UI.HtmlTextWriterAttribute.Cellpadding, "0", false);
            //制定一个表，把子控件排在一行上            output.RenderBeginTag(HtmlTextWriterTag.Table);  //表            output.RenderBeginTag(HtmlTextWriterTag.Tr);     //行
            output.RenderBeginTag(HtmlTextWriterTag.Td);     //列
            this._LBname.RenderControl(output);
            output.RenderEndTag();
            output.RenderBeginTag(HtmlTextWriterTag.Td);     //列
            this._TBname.RenderControl(output);
            output.RenderEndTag();
            output.RenderEndTag();            output.RenderBeginTag(HtmlTextWriterTag.Tr);     //行
            output.RenderBeginTag(HtmlTextWriterTag.Td);     //列
            this._LBPwd.RenderControl(output);
            output.RenderEndTag();
            output.RenderBeginTag(HtmlTextWriterTag.Td);     //列
            this._TBPwd.RenderControl(output);
            output.RenderEndTag();
            output.RenderEndTag();
            output.RenderBeginTag(HtmlTextWriterTag.Tr);     //行
            output.RenderBeginTag(HtmlTextWriterTag.Td);     //列
            this._BTLogOn.RenderControl(output);
            output.RenderEndTag();
            output.RenderBeginTag(HtmlTextWriterTag.Td);     //列
            this._BTCancel.RenderControl(output);
            output.RenderEndTag();
            output.RenderEndTag();            output.RenderEndTag();            output.WriteEncodedText("AA");
        }那位帮忙 呢 谢谢啦！！

Answer 1

如果 把 上面的 注解 output.WriteEncodedText("AA"); 
有时也能 打印出 

Answer 2

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}:WebLogonForm runat=server></{0}:WebLogonForm>")]
    public class WebLogonForm : System.Web.UI.WebControls.WebControl, INamingContainer
    {        private  System.Web.UI.WebControls.Label _LBname;        /// <summary>
        /// 设置或获取“用户名”这个文字 
        /// </summary>
        public string LBNameText
        {
            get { return _LBname.Text; }
            set { _LBname.Text = value; }
        }
        private  System.Web.UI.WebControls.Label _LBPwd;
        /// <summary>
        ///设置或获取“密码”这个文字 
        /// </summary>
        public string  LBPwdText
        {
            get { return _LBPwd.Text; }
            set { _LBPwd.Text = value; }
        }
        private System.Web.UI.WebControls.TextBox _TBname;
        /// <summary>
        /// 设置或获取用户名
        /// </summary>
        public string  TBNameText
        {
            get { return _TBname.Text; }
            set { _TBname.Text = value; }
        }
        private System.Web.UI.WebControls.TextBox _TBPwd;
        /// <summary>
        /// 设置或获取用户密码
        /// </summary>
        public string TBPwdText
        {
            get { return _TBPwd.Text; }
            set { _TBPwd.Text = value; }
        }
        private System.Web.UI.WebControls.Button _BTLogOn;
        /// <summary>
        /// 设置或获取登录按钮的文字
        /// </summary>
        public System.Web.UI.WebControls.Button BTLogOn
        {
            get { return _BTLogOn; }
            set { _BTLogOn = value; }
        }
        private System.Web.UI.WebControls.Button _BTCancel;
        /// <summary>
        /// 设置或获取取消按钮的文字
        /// </summary>
        public System.Web.UI.WebControls.Button BTCancel
        {
            get { return _BTCancel; }
            set { _BTCancel = value; }
        }        public event WebLogonButtonEventHandler BTLogOnOnClick;
       //{
       //    add
       //    {
       //        this.BTLogOnOnClick+=new WebLogonButtonEventHandler(value);
       //        //this.BTLogOn.Click+= new (EventHandler)WebLogonButtonEventHandler(value);
       //    }
       //    remove
       //    {
       //        this.BTLogOnOnClick -= new WebLogonButtonEventHandler(value);
       //    }
       //}        public event WebLogonButtonEventHandler BTCancelOnClick;
        //{
        //    add
        //    {
        //        this.BTCancelOnClick += new WebLogonButtonEventHandler(value);
        //    }
        //    remove
        //    {
        //        this.BTCancelOnClick += new WebLogonButtonEventHandler(value);
        //    }
        //}        //重载Controls属性，取得ControlCollection对象，该对象表示UI层次结构中的服务器控件的子控件
        //public override ControlCollection Controls
        //{
        //    get
        //    {
        //        //确定服务器是否包含子控件
        //        EnsureChildControls();
        //        return base.Controls;
        //    }
        //}       //动态创建子控件
        protected override void CreateChildControls()
        {
            
            this.Controls.Clear();
            this._TBname = new TextBox();
            this._TBPwd = new TextBox();
            this._LBname = new Label();
            this._LBPwd = new Label();
            this._BTLogOn = new Button();
            this._BTCancel = new Button();            this._BTLogOn.Click += new EventHandler(_BTLogOn_Click);
            this._BTCancel.Click += new EventHandler(_BTCancel_Click);
            base.CreateChildControls();
        }        void _BTCancel_Click(object sender, EventArgs e)
        {
            if (this.BTCancelOnClick!=null)
            {
                this.BTCancelOnClick(this,e);
            }
        }        void _BTLogOn_Click(object sender, EventArgs e)
        {
            if (this.BTLogOnOnClick!=null)
            {
                this.BTLogOnOnClick(this,e); 
            }
        }        /// <summary>
        ///  将此控件呈现给指定的输出参数
        /// </summary>
        /// <param name="output">要写出到的 HTML 编写器</param>
        protected override void RenderContents(HtmlTextWriter output)
        {
            output.Write(Text);
           // 将要呈现的HTML属性添加到指定的System.Web.HtmlTextWriter中
            AddAttributesToRender(output);
            output.AddAttribute(System.Web.UI.HtmlTextWriterAttribute.Cellpadding, "0", false);
            //制定一个表，把子控件排在一行上            output.RenderBeginTag(HtmlTextWriterTag.Table);  //表            output.RenderBeginTag(HtmlTextWriterTag.Tr);     //行
            output.RenderBeginTag(HtmlTextWriterTag.Td);     //列
            this._LBname.RenderControl(output);
            output.RenderEndTag();
            output.RenderBeginTag(HtmlTextWriterTag.Td);     //列
            this._TBname.RenderControl(output);
            output.RenderEndTag();
            output.RenderEndTag();            output.RenderBeginTag(HtmlTextWriterTag.Tr);     //行
            output.RenderBeginTag(HtmlTextWriterTag.Td);     //列
            this._LBPwd.RenderControl(output);
            output.RenderEndTag();
            output.RenderBeginTag(HtmlTextWriterTag.Td);     //列
            this._TBPwd.RenderControl(output);
            output.RenderEndTag();
            output.RenderEndTag();
            output.RenderBeginTag(HtmlTextWriterTag.Tr);     //行
            output.RenderBeginTag(HtmlTextWriterTag.Td);     //列
            this._BTLogOn.RenderControl(output);
            output.RenderEndTag();
            output.RenderBeginTag(HtmlTextWriterTag.Td);     //列
            this._BTCancel.RenderControl(output);
            output.RenderEndTag();
            output.RenderEndTag();            output.RenderEndTag();
            output.WriteEncodedText("AAA");
        }
        [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;
            }
        }    }
}
那位帮我看看呢 真的 不知道错在那里 是一 个 用户登录的 FORM  

Answer 3

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}:WebLogonForm runat=server></{0}:WebLogonForm>")]
    public class WebLogonForm : System.Web.UI.WebControls.WebControl, INamingContainer
    {        private  System.Web.UI.WebControls.Label _LBname;        /// <summary>
        /// 设置或获取“用户名”这个文字 
        /// </summary>
        public string LBNameText
        {
            get { return _LBname.Text; }
            set { _LBname.Text = value; }
        }
        private  System.Web.UI.WebControls.Label _LBPwd;
        /// <summary>
        ///设置或获取“密码”这个文字 
        /// </summary>
        public string  LBPwdText
        {
            get { return _LBPwd.Text; }
            set { _LBPwd.Text = value; }
        }
        private System.Web.UI.WebControls.TextBox _TBname;
        /// <summary>
        /// 设置或获取用户名
        /// </summary>
        public string  TBNameText
        {
            get { return _TBname.Text; }
            set { _TBname.Text = value; }
        }
        private System.Web.UI.WebControls.TextBox _TBPwd;
        /// <summary>
        /// 设置或获取用户密码
        /// </summary>
        public string TBPwdText
        {
            get { return _TBPwd.Text; }
            set { _TBPwd.Text = value; }
        }
        private System.Web.UI.WebControls.Button _BTLogOn;
        /// <summary>
        /// 设置或获取登录按钮的文字
        /// </summary>
        public System.Web.UI.WebControls.Button BTLogOn
        {
            get { return _BTLogOn; }
            set { _BTLogOn = value; }
        }
        private System.Web.UI.WebControls.Button _BTCancel;
        /// <summary>
        /// 设置或获取取消按钮的文字
        /// </summary>
        public System.Web.UI.WebControls.Button BTCancel
        {
            get { return _BTCancel; }
            set { _BTCancel = value; }
        }        public event WebLogonButtonEventHandler BTLogOnOnClick;
       //{
       //    add
       //    {
       //        this.BTLogOnOnClick+=new WebLogonButtonEventHandler(value);
       //        //this.BTLogOn.Click+= new (EventHandler)WebLogonButtonEventHandler(value);
       //    }
       //    remove
       //    {
       //        this.BTLogOnOnClick -= new WebLogonButtonEventHandler(value);
       //    }
       //}        public event WebLogonButtonEventHandler BTCancelOnClick;
        //{
        //    add
        //    {
        //        this.BTCancelOnClick += new WebLogonButtonEventHandler(value);
        //    }
        //    remove
        //    {
        //        this.BTCancelOnClick += new WebLogonButtonEventHandler(value);
        //    }
        //}        //重载Controls属性，取得ControlCollection对象，该对象表示UI层次结构中的服务器控件的子控件
        //public override ControlCollection Controls
        //{
        //    get
        //    {
        //        //确定服务器是否包含子控件
        //        EnsureChildControls();
        //        return base.Controls;
        //    }
        //}       //动态创建子控件
        protected override void CreateChildControls()
        {
            
            this.Controls.Clear();
            this._TBname = new TextBox();
            this._TBPwd = new TextBox();
            this._LBname = new Label();
            this._LBPwd = new Label();
            this._BTLogOn = new Button();
            this._BTCancel = new Button();            this._BTLogOn.Click += new EventHandler(_BTLogOn_Click);
            this._BTCancel.Click += new EventHandler(_BTCancel_Click);
            base.CreateChildControls();
        }        void _BTCancel_Click(object sender, EventArgs e)
        {
            if (this.BTCancelOnClick!=null)
            {
                this.BTCancelOnClick(this,e);
            }
        }        void _BTLogOn_Click(object sender, EventArgs e)
        {
            if (this.BTLogOnOnClick!=null)
            {
                this.BTLogOnOnClick(this,e); 
            }
        }        /// <summary>
        ///  将此控件呈现给指定的输出参数
        /// </summary>
        /// <param name="output">要写出到的 HTML 编写器</param>
        protected override void RenderContents(HtmlTextWriter output)
        {
            output.Write(Text);
           // 将要呈现的HTML属性添加到指定的System.Web.HtmlTextWriter中
            AddAttributesToRender(output);
            output.AddAttribute(System.Web.UI.HtmlTextWriterAttribute.Cellpadding, "0", false);
            //制定一个表，把子控件排在一行上            output.RenderBeginTag(HtmlTextWriterTag.Table);  //表            output.RenderBeginTag(HtmlTextWriterTag.Tr);     //行
            output.RenderBeginTag(HtmlTextWriterTag.Td);     //列
            this._LBname.RenderControl(output);
            output.RenderEndTag();
            output.RenderBeginTag(HtmlTextWriterTag.Td);     //列
            this._TBname.RenderControl(output);
            output.RenderEndTag();
            output.RenderEndTag();            output.RenderBeginTag(HtmlTextWriterTag.Tr);     //行
            output.RenderBeginTag(HtmlTextWriterTag.Td);     //列
            this._LBPwd.RenderControl(output);
            output.RenderEndTag();
            output.RenderBeginTag(HtmlTextWriterTag.Td);     //列
            this._TBPwd.RenderControl(output);
            output.RenderEndTag();
            output.RenderEndTag();
            output.RenderBeginTag(HtmlTextWriterTag.Tr);     //行
            output.RenderBeginTag(HtmlTextWriterTag.Td);     //列
            this._BTLogOn.RenderControl(output);
            output.RenderEndTag();
            output.RenderBeginTag(HtmlTextWriterTag.Td);     //列
            this._BTCancel.RenderControl(output);
            output.RenderEndTag();
            output.RenderEndTag();            output.RenderEndTag();
            output.WriteEncodedText("AAA");
        }
        [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;
            }
        }    }
}
那位帮我看看呢 真的 不知道错在那里 是一 个 用户登录的 FORM  

Answer 4

可以了 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}:WebLogonForm runat=server></{0}:WebLogonForm>")]
    public class WebLogonForm : CompositeControl
    {
        private Table containerTable=null;
        private  System.Web.UI.WebControls.Label _LBname;        /// <summary>
        /// 设置或获取“用户名”这个文字 
        /// </summary>
        public string LBNameText
        {
            get { return _LBname.Text; }
            set { _LBname.Text = value; }
        }
        private  System.Web.UI.WebControls.Label _LBPwd;
        /// <summary>
        ///设置或获取“密码”这个文字 
        /// </summary>
        public string  LBPwdText
        {
            get { return _LBPwd.Text; }
            set { _LBPwd.Text = value; }
        }
        private System.Web.UI.WebControls.TextBox _TBname;
        /// <summary>
        /// 设置或获取用户名
        /// </summary>
        public string  TBNameText
        {
            get { return _TBname.Text; }
            set { _TBname.Text = value; }
        }
        private System.Web.UI.WebControls.TextBox _TBPwd;
        /// <summary>
        /// 设置或获取用户密码
        /// </summary>
        public string TBPwdText
        {
            get { return _TBPwd.Text; }
            set { _TBPwd.Text = value; }
        }
        private System.Web.UI.WebControls.Button _BTLogOn;
        /// <summary>
        /// 设置或获取登录按钮的文字
        /// </summary>
        public System.Web.UI.WebControls.Button BTLogOn
        {
            get { return _BTLogOn; }
            set { _BTLogOn = value; }
        }
        private System.Web.UI.WebControls.Button _BTCancel;
        /// <summary>
        /// 设置或获取取消按钮的文字
        /// </summary>
        public System.Web.UI.WebControls.Button BTCancel
        {
            get { return _BTCancel; }
            set { _BTCancel = value; }
        }        public event WebLogonButtonEventHandler BTLogOnOnClick;
       //{
       //    add
       //    {
       //        this.BTLogOnOnClick+=new WebLogonButtonEventHandler(value);
       //        //this.BTLogOn.Click+= new (EventHandler)WebLogonButtonEventHandler(value);
       //    }
       //    remove
       //    {
       //        this.BTLogOnOnClick -= new WebLogonButtonEventHandler(value);
       //    }
       //}        public event WebLogonButtonEventHandler BTCancelOnClick;
        //{
        //    add
        //    {
        //        this.BTCancelOnClick += new WebLogonButtonEventHandler(value);
        //    }
        //    remove
        //    {
        //        this.BTCancelOnClick += new WebLogonButtonEventHandler(value);
        //    }
        //}        //重载Controls属性，取得ControlCollection对象，该对象表示UI层次结构中的服务器控件的子控件
        //public override ControlCollection Controls
        //{
        //    get
        //    {
        //        //确定服务器是否包含子控件
        //        EnsureChildControls();
        //        return base.Controls;
        //    }
        //}       //动态创建子控件
        //protected override void CreateChildControls()
        //{
            
        //    //this.Controls.Clear();        //    //base.CreateChildControls();
        //}
        public WebLogonForm()
        {
            this._TBname = new TextBox();
            this._TBPwd = new TextBox();            this._LBname = new Label();
            this._LBname.Text = "用户名：";
            this._LBPwd = new Label();
            this._LBPwd.Text = "密码：";            this._BTLogOn = new Button();
            this._BTLogOn.Text = "登录";
            this._BTCancel = new Button();
            this._BTCancel.Text = "取消";            this.containerTable = new Table();            this._BTLogOn.Click += new EventHandler(_BTLogOn_Click);
            this._BTCancel.Click += new EventHandler(_BTCancel_Click);
        }        protected override void CreateChildControls()
        {
            TableCell cell00 = new TableCell();
            cell00.Controls.Add(this._LBname);
            TableCell cell01 = new TableCell();
            cell01.Controls.Add(this._TBname);
            TableRow row0 = new TableRow();
            row0.Cells.Add(cell00);
            row0.Cells.Add(cell01);
            this.containerTable.Rows.Add(row0);
            TableCell cell10 = new TableCell();
            cell10.Controls.Add(this._LBPwd);
            TableCell cell11 = new TableCell();
            cell11.Controls.Add(this._TBPwd);
            TableRow row1 = new TableRow();
            row1.Cells.Add(cell10);
            row1.Cells.Add(cell11);
            this.containerTable.Rows.Add(row1);            TableCell cell20 = new TableCell();
            cell20.Controls.Add(this._BTLogOn);
            TableCell cell21 = new TableCell();
            cell21.Controls.Add(this._BTCancel);
            TableRow row2 = new TableRow();
            row2.Cells.Add(cell20);
            row2.Cells.Add(cell21);
            this.containerTable.Rows.Add(row2);            this.Controls.Add(this.containerTable);
        }        void _BTCancel_Click(object sender, EventArgs e)
        {
            if (this.BTCancelOnClick!=null)
            {
                this.BTCancelOnClick(this,e);
            }
        }        void _BTLogOn_Click(object sender, EventArgs e)
        {
            if (this.BTLogOnOnClick!=null)
            {
                this.BTLogOnOnClick(this,e); 
            }
        }    }
}