用户控件事件为null问题

显示全部楼层 · 2014-6-20 11:53:07

ascx页面
public delegate void AddClickHandler(object sender, AddEventArgs e); //定义添加按钮委托
      public event AddClickHandler AddClick;//定义事件
protected void btnBindBandCard_Click(object sender, EventArgs e)
      {
         try
         {
            AddEventArgs addEvent = new AddEventArgs();
            addEvent.IsSuccess = true;
            if(AddClick !=null)这块总是为null,求解
            {
                  AddClick(sender, addEvent);
            }

         }
         catch(Exception ex)
         {
            AddEventArgs addEvent = new AddEventArgs();
            addEvent.IsSuccess = false;

         }
      }

public class AddEventArgs : EventArgs
{
      bool isSuccess;

      public bool IsSuccess
      {
         get { return isSuccess; }
         set { isSuccess = value; }
      }

}
aspx页面
   if(!IsPostBack)
         {
                     bandCard.AddClick += bandCard_AddClick;
         }

      void bandCard_AddClick(object sender, Common.Ascx.AddEventArgs e)
      {
         if (e.IsSuccess)
         {
            Response.Write("成功");
         }
         else
         {
            Response.Write("失败");
         }
      }

songyusb · 2014-6-20 11:55:01

我是路过的酱油哥~

ibcadmin · 2014-6-20 12:04:21

给你两个例子你看下，你把ispostback去掉试一下，为空多部分表示页面回传的问题。
例子一：

[C#] 纯文本查看 复制代码

//声明事件委托
     public delegate void ToolClickEventHandler(Object sender, EventArgs e);
     //定义事件
     public event ToolClickEventHandler ToolBtnClick;
     //监视事件
     protected void OnToolClick(Object sender, EventArgs e)
     {
         if (ToolBtnClick != null)
         {
             ToolBtnClick(sender, e);
         }
     }
     private static System.Web.UI.WebControls.Button New;
     protected void Page_Load(object sender, EventArgs e)
     {
         if (!IsPostBack)
         {
             for (int i = 0; i < btnNum; i++)
             {    
                 New = new Button();
                 New.Text = arrayBtnText[i];
                 New.ID = "btnNew"+i.ToString();
                 //页面回传时点击事件委托无效
                 //New.Click += new System.EventHandler(btnNew_Click);
                 //动态产生的按钮，页面不能保存他的状态，页面回传时就没有了，缓存起来，页面回传时重新加载
                 if(btnCssClass!=null)
                 {
                     New.CssClass = btnCssClass;
                 }
                 Cache["New"+i.ToString()] = New;         
             }
         }
         if (panelCssClass != null)
         {
             Panel1.CssClass = panelCssClass;
         }
         Panel1.Controls.Clear();
         for (int j = 0; j < btnNum;j++ )
             if (Cache["New" + j.ToString()] != null)
             {
                 Button old = (Button)Cache["New" + j.ToString()];
                 //一下这两个属性本应该是在具体应用程序中去设置，但因为这两个按钮的这两个属性具有一般性
                 //所以就在这里进行设置
                 if (old.Text != "提交" && old.Text != "保存")
                 {
                     old.CausesValidation = false;
                 }
                 if (old.Text == "删除" || old.Text=="清除")
                 {
                     old.Attributes.Add("onclick", "javascript:return confirm('Are you sure to delete?');");
                 }
                 old.Click += new System.EventHandler(btnNew_Click);
                 Panel1.Controls.Add((Control)Cache["New" + j.ToString()]);
             }
     }
     public void btnNew_Click(Object sender, EventArgs e)
     {
         //Button btn = (Button)sender;
         //str = btn.ID;
         //Response.Write("<script>alert('"+str+"')</script>");
         OnToolClick(sender, e);
     }

例子二：

[C#] 纯文本查看 复制代码

using System;

public class MyClass
{

public static void Main()
{

PrintStr myPrinter = new PrintStr();

PrintHandler myHandler = null;

myHandler += new PrintHandler(myPrinter.CallPrint); // 将委托链接到方法，来实例化委托

if(myHandler!=null)

myHandler("Hello World!"); // 调用委托，相当于匿名调用委托所链接的方法

Console.Read();

}

}



public delegate void PrintHandler(string str); // 声明委托类型

public class PrintStr
{

public void CallPrint(string input)

{

Console.WriteLine(input);

}

}

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