web控件给button添加事件问题

Question

 代码如下[Bindable(true)]
        [Category("Appearance")]
        [DefaultValue("")]
        [Localizable(true)]
        public String ButtonControlID
        {
            get
            {
                String s = (String)ViewState["ButtonControlID"];
                return ((s == null) ? String.Empty : s);
            }            set
            {
                ViewState["ButtonControlID"] = value;
            }
        }
        
        protected virtual Button GetButton()
        {
            if (string.IsNullOrEmpty(this.ButtonControlID))
                throw new HttpException("缺少ButtonControlID属性!");            Button btn=this.FindControl(this.ButtonControlID) as Button;            if (btn==null)
                throw new HttpException ("缺少控制控件!");
            return btn;
        }        protected override void OnPreRender(EventArgs e)
        {
            base.OnPreRender(e);            if (this.Enabled)
            {
                Button btn = GetButton();
                btn.Click+=new System.EventHandler(btn_Click);            }
        }
        public void btn_Click(object sender, EventArgs e)
        {
        } 
这么做是否可以???或者按此思路是否可行???

Answer 1

如果要绑定事件，应该在LoadComplete事件执行完毕之前就绑定。当页面回发处理时，在LoadComplete执行完就要开始触发事件了。如果在PreRender才绑定事件，永远也不会触发。

Answer 2

你这个应该属于复合控件。
应该继承WebControl, INamingContainer
然后重写CreateChildControls()，在里面生成控件，
比如： #region 生成控件
        protected override void CreateChildControls()
        {
            this.Controls.Clear();
            _btnChangePage = new Button();
            _btnChangePage.ID = "btnChangePage";
            _btnChangePage.Click += new EventHandler(BtnChangePage_Click);
            _lblCurrentPage = new Label();
            _lblCurrentPage.ID = "lblCurrentPage";
            _lblPageCount = new Label();
            _lblPageCount.ID = "lblPageCount";
            _lblRecodeCount = new Label();
            _lblRecodeCount.ID = "lblRecodeCount";
            _lnkbtnFrist = new LinkButton();
            _lnkbtnFrist.ID = "lnkbtnFrist";
            _lnkbtnFrist.Click += new EventHandler(lnkbtnFrist_Click);
            _lnkbtnLast = new LinkButton();
            _lnkbtnLast.ID = "lnkbtnLast";
            _lnkbtnLast.Click += new EventHandler(lnkbtnLast_Click);
            _lnkbtnNext = new LinkButton();
            _lnkbtnNext.ID = "lnkbtnNext";
            _lnkbtnNext.Click += new EventHandler(lnkbtnNext_Click);
            _lnkbtnPre = new LinkButton();
            _lnkbtnPre.ID = "lnkbtnPre";
            _lnkbtnPre.Click += new EventHandler(lnkbtnPre_Click);
            _page_0 = new LinkButton();
            _page_0.ID = "_page_0";
            _page_0.Click += new EventHandler(CurrentPage_Click);
            _page_1 = new LinkButton();
            _page_1.ID = "_page_1";
            _page_1.Click += new EventHandler(CurrentPage_Click);
            _page_2 = new LinkButton();
            _page_2.ID = "_page_2";
            _page_2.Click += new EventHandler(CurrentPage_Click);
            _page_3 = new LinkButton();
            _page_3.ID = "_page_3";
            _page_3.Click += new EventHandler(CurrentPage_Click);
            _page_4 = new LinkButton();
            _page_4.ID = "_page_4";
            _page_4.Click += new EventHandler(CurrentPage_Click);
            _page_5 = new LinkButton();
            _page_5.ID = "_page_5";
            _page_5.Click += new EventHandler(CurrentPage_Click);
            _page_6 = new LinkButton();
            _page_6.ID = "_page_6";
            _page_6.Click += new EventHandler(CurrentPage_Click);
            _page_7 = new LinkButton();
            _page_7.ID = "_page_7";
            _page_7.Click += new EventHandler(CurrentPage_Click);
            _page_8 = new LinkButton();
            _page_8.ID = "_page_8";
            _page_8.Click += new EventHandler(CurrentPage_Click);
            _page_9 = new LinkButton();
            _page_9.ID = "_page_9";
            _page_9.Click += new EventHandler(CurrentPage_Click);
            _txtPageIndex = new TextBox();
            _txtPageIndex.ID = "txtPageIndex";
            _lblPageSize = new Label();
            _lblPageSize.ID = "lblPageSize";
            this.Controls.Add(_page_0);
            this.Controls.Add(_page_1);
            this.Controls.Add(_page_2);
            this.Controls.Add(_page_3);
            this.Controls.Add(_page_4);
            this.Controls.Add(_page_5);
            this.Controls.Add(_page_6);
            this.Controls.Add(_page_7);
            this.Controls.Add(_page_8);
            this.Controls.Add(_page_9);
            this.Controls.Add(_btnChangePage);
            this.Controls.Add(_lblCurrentPage);
            this.Controls.Add(_lblPageCount);
            this.Controls.Add(_lblRecodeCount);
            this.Controls.Add(_lnkbtnFrist);
            this.Controls.Add(_lnkbtnLast);
            this.Controls.Add(_lnkbtnNext);
            this.Controls.Add(_lnkbtnPre);
            this.Controls.Add(_txtPageIndex);
            base.CreateChildControls();
            ChildControlsCreated = true; //指示控件已经生成，避免多次重复生成控件
        }
        #endregion

Answer 3

如果属性用到里面的子控件，
则需要判断是否已经生成该控件，比如：
 [Category("Appearance"), Description("设置跳转按钮的文本"),
      DefaultValue(":"), Bindable(true)]
        public virtual string ButtonText
        {
            get
            {
                EnsureChildControls();//判断控件是否已经生成，如果未生成，则调用CreateChildControls生成控件再使用
                return _btnChangePage.Text.Trim() != "" ? _btnChangePage.Text.Trim() : "GO";
            }
            set
            {
                EnsureChildControls();
                _btnChangePage.Text = value;
            }
        }