这几天有几人在问类似的问题，“动态加载控件，为什么控件事件不能触发了？”，问题是他们都是在
if (!IsPostBack)
{
//动态产生或装载控件
//也许需要连接控件事件处理函数
//加到父控件的Controls
}
里生成或装载了动态控件。当控件在客户端触发，postback到服务器端时，IsPostBack==true，这些控件没有被重新生成，怎么能触发事件？所以答案是，当你需要动态生成或装载控件时，应该在if (!IsPostBack)之外做。我问为什么想在if (!IsPostBack)之内做呢？回答是想只生成一次，跟在ASPX页面里一样
<form id=”form1″ runat=server>
<asp:Button id=”Button1″ runat=”server” Text=”Button1″ OnClick=”Button_Click”/>
#%&%#&%^#&，你怎么会认为这个控件只生成一次呢？这些玩意也不是魔术，想生成一个Button对象，你需要用
Button btn = new Button();
需要触发它的Click事件，你需要用
btn.Click += new EventHandler(YourHandler);
即使象包含
<asp:Button id=”Button1″ runat=”server” Text=”Button1″ OnClick=”Button_Click”/>
的页面，它也是被转化成C#或VB文件，编译成assembly，然后再被执行的啊
不信？加一个页面，TestControls.aspx：
<%@ Page Debug=”true” %>
<%@ Import Namespace=”System.Data”%>
<%@ Import Namespace=”System.Data.SqlClient”%>
<form id=”form1″ runat=server>
<asp:Button id=”Button1″ runat=”server” Text=”Button1″ OnClick=”Button_Click”/>
<asp:DataGrid id=”DataGrid1″ runat=”server” AutoGenerateColumns=”false” GridLines=”Both”>
<Columns>
<asp:TemplateColumn HeaderText=”Name”>
<ItemTemplate><%# DataBinder.Eval(Container.DataItem,”Name”)%></ItemTemplate>
</asp:TemplateColumn>
</Columns>
</asp:DataGrid>
</form>
void Button_Click(Object sender, EventArgs e)
{
Button btn = (Button)sender;
Response.Write(btn.Text + ” is clicked
“);
}
void Page_Load(Object sender, EventArgs e)
{
Button btn = new Button();
btn.ID = “Button2”;
btn.Text = “Button2”;
btn.Click += new EventHandler(Button_Click);
form1.Controls.Add(btn);
if (!IsPostBack)
{
SqlDataAdapter da = new SqlDataAdapter(“select Name=au_fname + ‘ ‘ + au_lname from authors”, “server=localhost;database=pubs;uid=sa;pwd=;”);
DataTable dt = new DataTable();
da.Fill(dt);
DataGrid1.DataSource = dt.DefaultView;
DataGrid1.DataBind();
}
//}//这是故意的
function ShowAutoCode()
{
var e = document.getElementById(“dvAutoCode”);
if (e.style.display == “”) e.style.display = “none”;
else e.style.display = “”;
}
把最后一个“}”注释掉，然后在浏览器里向你的服务器调用TestControls.aspx，你将看到编译错误，按 ，你将看到:
Line 1: //------------------------------------------------------------------------------
Line 2: //
Line 3: // This code was generated by a tool.
Line 4: // Runtime Version: 1.1.4322.573
Line 5: //
Line 6: // Changes to this file may cause incorrect behavior and will be lost if
Line 7: // the code is regenerated.
Line 8: //
Line 9: //------------------------------------------------------------------------------
Line 10:
Line 11: namespace ASP {
Line 12: using System;
Line 13: using System.Collections;
Line 14: using System.Collections.Specialized;
Line 15: using System.Configuration;
Line 16: using System.Text;
Line 17: using System.Text.RegularExpressions;
Line 18: using System.Web;
Line 19: using System.Web.Caching;
Line 20: using System.Web.SessionState;
Line 21: using System.Web.Security;
Line 22: using System.Web.UI;
Line 23: using System.Web.UI.WebControls;
Line 24: using System.Web.UI.HtmlControls;
Line 25: using ASP;
Line 26:
Line 27: #line 2 "E:\labs\aspnet\TestControls.aspx"
Line 28: using System.Data;
Line 29:
Line 30: #line default
Line 31: #line hidden
Line 32:
Line 33: #line 3 "E:\labs\aspnet\TestControls.aspx"
Line 34: using System.Data.SqlClient;
Line 35:
Line 36: #line default
Line 37: #line hidden
Line 38:
Line 39:
Line 40: [System.Runtime.CompilerServices.CompilerGlobalScopeAttribute()]
Line 41: public class TestControls_aspx : System.Web.UI.Page, System.Web.SessionState.IRequiresSessionState {
Line 42:
Line 43: private static int __autoHandlers;
Line 44:
Line 45:
Line 46: #line 6 "E:\labs\aspnet\TestControls.aspx"
Line 47: protected System.Web.UI.WebControls.Button Button1;
Line 48:
Line 49: #line default
Line 50: #line hidden
Line 51:
Line 52: private System.Web.UI.DataBoundLiteralControl __control5;
Line 53:
Line 54:
Line 55: #line 9 "E:\labs\aspnet\TestControls.aspx"
Line 56: private System.Web.UI.WebControls.TemplateColumn __control3;
Line 57:
Line 58: #line default
Line 59: #line hidden
Line 60:
Line 61:
Line 62: #line 7 "E:\labs\aspnet\TestControls.aspx"
Line 63: private System.Web.UI.WebControls.DataGridColumnCollection __control2;
Line 64:
Line 65: #line default
Line 66: #line hidden
Line 67:
Line 68:
Line 69: #line 7 "E:\labs\aspnet\TestControls.aspx"
Line 70: protected System.Web.UI.WebControls.DataGrid DataGrid1;
Line 71:
Line 72: #line default
Line 73: #line hidden
Line 74:
Line 75:
Line 76: #line 5 "E:\labs\aspnet\TestControls.aspx"
Line 77: protected System.Web.UI.HtmlControls.HtmlForm form1;
Line 78:
Line 79: #line default
Line 80: #line hidden
Line 81:
Line 82: private static bool __initialized = false;
Line 83:
Line 84: private static System.Collections.ArrayList __fileDependencies;
Line 85:
Line 86:
Line 87: #line 15 "E:\labs\aspnet\TestControls.aspx"
Line 88:
Line 89: void Button_Click(Object sender, EventArgs e)
Line 90: {
Line 91: Button btn = (Button)sender;
Line 92: Response.Write(btn.Text + " is clicked<BR>");
Line 93: }
Line 94:
Line 95: void Page_Load(Object sender, EventArgs e)
Line 96: {
Line 97:
Line 98: Button btn = new Button();
Line 99: btn.ID = "Button2";
Line 100: btn.Text = "Button2";
Line 101: btn.Click += new EventHandler(Button_Click);
Line 102: form1.Controls.Add(btn);
Line 103: if (!IsPostBack)
Line 104: {
Line 105: SqlDataAdapter da = new SqlDataAdapter("select Name=au_fname + ' ' + au_lname from authors", "server=localhost;database=pubs;uid=sa;pwd=;");
Line 106: DataTable dt = new DataTable();
Line 107: da.Fill(dt);
Line 108: DataGrid1.DataSource = dt.DefaultView;
Line 109: DataGrid1.DataBind();
Line 110: }
Line 111:
Line 112:
Line 113: //}
Line 114:
Line 115:
Line 116: #line default
Line 117: #line hidden
Line 118:
Line 119: public TestControls_aspx() {
Line 120: System.Collections.ArrayList dependencies;
Line 121: if ((ASP.TestControls_aspx.__initialized == false)) {
Line 122: dependencies = new System.Collections.ArrayList();
Line 123: dependencies.Add("E:\\labs\\aspnet\\TestControls.aspx");
Line 124: ASP.TestControls_aspx.__fileDependencies = dependencies;
Line 125: ASP.TestControls_aspx.__initialized = true;
Line 126: }
Line 127: this.Server.ScriptTimeout = 30000000;
Line 128: }
Line 129:
Line 130: protected override int AutoHandlers {
Line 131: get {
Line 132: return ASP.TestControls_aspx.__autoHandlers;
Line 133: }
Line 134: set {
Line 135: ASP.TestControls_aspx.__autoHandlers = value;
Line 136: }
Line 137: }
Line 138:
Line 139: protected ASP.global_asax ApplicationInstance {
Line 140: get {
Line 141: return ((ASP.global_asax)(this.Context.ApplicationInstance));
Line 142: }
Line 143: }
Line 144:
Line 145: public override string TemplateSourceDirectory {
Line 146: get {
Line 147: return "/labs/aspnet";
Line 148: }
Line 149: }
Line 150:
Line 151: private System.Web.UI.Control __BuildControlButton1() {
Line 152: System.Web.UI.WebControls.Button __ctrl;
Line 153:
Line 154: #line 6 "E:\labs\aspnet\TestControls.aspx"
Line 155: __ctrl = new System.Web.UI.WebControls.Button();
Line 156:
Line 157: #line default
Line 158: #line hidden
Line 159: this.Button1 = __ctrl;
Line 160:
Line 161: #line 6 "E:\labs\aspnet\TestControls.aspx"
Line 162: __ctrl.ID = "Button1";
Line 163:
Line 164: #line default
Line 165: #line hidden
Line 166:
Line 167: #line 6 "E:\labs\aspnet\TestControls.aspx"
Line 168: __ctrl.Text = "Button1";
Line 169:
Line 170: #line default
Line 171: #line hidden
Line 172:
Line 173: #line 6 "E:\labs\aspnet\TestControls.aspx"
Line 174: __ctrl.Click += new System.EventHandler(this.Button_Click);
Line 175:
Line 176: #line default
Line 177: #line hidden
Line 178: return __ctrl;
Line 179: }
Line 180:
Line 181: private System.Web.UI.Control __BuildControl__control5() {
Line 182: System.Web.UI.DataBoundLiteralControl __ctrl;
Line 183: __ctrl = new System.Web.UI.DataBoundLiteralControl(1, 1);
Line 184: this.__control5 = __ctrl;
Line 185: __ctrl.DataBinding += new System.EventHandler(this.__DataBind__control5);
Line 186: return __ctrl;
Line 187: }
Line 188:
Line 189: public void __DataBind__control5(object sender, System.EventArgs e) {
Line 190: System.Web.UI.WebControls.DataGridItem Container;
Line 191: System.Web.UI.DataBoundLiteralControl target;
Line 192: target = ((System.Web.UI.DataBoundLiteralControl)(sender));
Line 193: Container = ((System.Web.UI.WebControls.DataGridItem)(target.BindingContainer));
Line 194:
Line 195: #line 10 "E:\labs\aspnet\TestControls.aspx"
Line 196: target.SetDataBoundString(0, System.Convert.ToString(DataBinder.Eval(Container.DataItem,"Name")));
Line 197:
Line 198: #line default
Line 199: #line hidden
Line 200: }
Line 201:
Line 202: private void __BuildControl__control4(System.Web.UI.Control __ctrl) {
Line 203:
Line 204: #line 9 "E:\labs\aspnet\TestControls.aspx"
Line 205: this.__BuildControl__control5();
Line 206:
Line 207: #line default
Line 208: #line hidden
Line 209: System.Web.UI.IParserAccessor __parser = ((System.Web.UI.IParserAccessor)(__ctrl));
Line 210:
Line 211: #line 9 "E:\labs\aspnet\TestControls.aspx"
Line 212: __parser.AddParsedSubObject(this.__control5);
Line 213:
Line 214: #line default
Line 215: #line hidden
Line 216: }
Line 217:
Line 218: private void __BuildControl__control3() {
Line 219: System.Web.UI.WebControls.TemplateColumn __ctrl;
Line 220:
Line 221: #line 9 "E:\labs\aspnet\TestControls.aspx"
Line 222: __ctrl = new System.Web.UI.WebControls.TemplateColumn();
Line 223:
Line 224: #line default
Line 225: #line hidden
Line 226: this.__control3 = __ctrl;
Line 227:
Line 228: #line 9 "E:\labs\aspnet\TestControls.aspx"
Line 229: __ctrl.HeaderText = "Name";
Line 230:
Line 231: #line default
Line 232: #line hidden
Line 233:
Line 234: #line 9 "E:\labs\aspnet\TestControls.aspx"
Line 235: __ctrl.ItemTemplate = new System.Web.UI.CompiledTemplateBuilder(new System.Web.UI.BuildTemplateMethod(this.__BuildControl__control4));
Line 236:
Line 237: #line default
Line 238: #line hidden
Line 239: }
Line 240:
Line 241: private void __BuildControl__control2(System.Web.UI.WebControls.DataGridColumnCollection __ctrl) {
Line 242:
Line 243: #line 7 "E:\labs\aspnet\TestControls.aspx"
Line 244: this.__BuildControl__control3();
Line 245:
Line 246: #line default
Line 247: #line hidden
Line 248:
Line 249: #line 7 "E:\labs\aspnet\TestControls.aspx"
Line 250: __ctrl.Add(this.__control3);
Line 251:
Line 252: #line default
Line 253: #line hidden
Line 254: }
Line 255:
Line 256: private System.Web.UI.Control __BuildControlDataGrid1() {
Line 257: System.Web.UI.WebControls.DataGrid __ctrl;
Line 258:
Line 259: #line 7 "E:\labs\aspnet\TestControls.aspx"
Line 260: __ctrl = new System.Web.UI.WebControls.DataGrid();
Line 261:
Line 262: #line default
Line 263: #line hidden
Line 264: this.DataGrid1 = __ctrl;
Line 265:
Line 266: #line 7 "E:\labs\aspnet\TestControls.aspx"
Line 267: __ctrl.ID = "DataGrid1";
Line 268:
Line 269: #line default
Line 270: #line hidden
Line 271:
Line 272: #line 7 "E:\labs\aspnet\TestControls.aspx"
Line 273: __ctrl.AutoGenerateColumns = false;
Line 274:
Line 275: #line default
Line 276: #line hidden
Line 277:
Line 278: #line 7 "E:\labs\aspnet\TestControls.aspx"
Line 279: __ctrl.GridLines = System.Web.UI.WebControls.GridLines.Both;
Line 280:
Line 281: #line default
Line 282: #line hidden
Line 283:
Line 284: #line 7 "E:\labs\aspnet\TestControls.aspx"
Line 285: this.__BuildControl__control2(__ctrl.Columns);
Line 286:
Line 287: #line default
Line 288: #line hidden
Line 289: return __ctrl;
Line 290: }
Line 291:
Line 292: private System.Web.UI.Control __BuildControlform1() {
Line 293: System.Web.UI.HtmlControls.HtmlForm __ctrl;
Line 294:
Line 295: #line 5 "E:\labs\aspnet\TestControls.aspx"
Line 296: __ctrl = new System.Web.UI.HtmlControls.HtmlForm();
Line 297:
Line 298: #line default
Line 299: #line hidden
Line 300: this.form1 = __ctrl;
Line 301:
Line 302: #line 5 "E:\labs\aspnet\TestControls.aspx"
Line 303: __ctrl.ID = "form1";
Line 304:
Line 305: #line default
Line 306: #line hidden
Line 307: System.Web.UI.IParserAccessor __parser = ((System.Web.UI.IParserAccessor)(__ctrl));
Line 308:
Line 309: #line 5 "E:\labs\aspnet\TestControls.aspx"
Line 310: __parser.AddParsedSubObject(new System.Web.UI.LiteralControl("\r\n"));
Line 311:
Line 312: #line default
Line 313: #line hidden
Line 314:
Line 315: #line 5 "E:\labs\aspnet\TestControls.aspx"
Line 316: this.__BuildControlButton1();
Line 317:
Line 318: #line default
Line 319: #line hidden
Line 320:
Line 321: #line 5 "E:\labs\aspnet\TestControls.aspx"
Line 322: __parser.AddParsedSubObject(this.Button1);
Line 323:
Line 324: #line default
Line 325: #line hidden
Line 326:
Line 327: #line 5 "E:\labs\aspnet\TestControls.aspx"
Line 328: __parser.AddParsedSubObject(new System.Web.UI.LiteralControl("\r\n"));
Line 329:
Line 330: #line default
Line 331: #line hidden
Line 332:
Line 333: #line 5 "E:\labs\aspnet\TestControls.aspx"
Line 334: this.__BuildControlDataGrid1();
Line 335:
Line 336: #line default
Line 337: #line hidden
Line 338:
Line 339: #line 5 "E:\labs\aspnet\TestControls.aspx"
Line 340: __parser.AddParsedSubObject(this.DataGrid1);
Line 341:
Line 342: #line default
Line 343: #line hidden
Line 344:
Line 345: #line 5 "E:\labs\aspnet\TestControls.aspx"
Line 346: __parser.AddParsedSubObject(new System.Web.UI.LiteralControl("\r\n"));
Line 347:
Line 348: #line default
Line 349: #line hidden
Line 350: return __ctrl;
Line 351: }
Line 352:
Line 353: private void __BuildControlTree(System.Web.UI.Control __ctrl) {
Line 354:
Line 355: #line 1 "E:\labs\aspnet\TestControls.aspx"
Line 356: this.__BuildControlform1();
Line 357:
Line 358: #line default
Line 359: #line hidden
Line 360: System.Web.UI.IParserAccessor __parser = ((System.Web.UI.IParserAccessor)(__ctrl));
Line 361:
Line 362: #line 1 "E:\labs\aspnet\TestControls.aspx"
Line 363: __parser.AddParsedSubObject(this.form1);
Line 364:
Line 365: #line default
Line 366: #line hidden
Line 367:
Line 368: #line 1 "E:\labs\aspnet\TestControls.aspx"
Line 369: __parser.AddParsedSubObject(new System.Web.UI.LiteralControl("\r\n"));
Line 370:
Line 371: #line default
Line 372: #line hidden
Line 373: }
Line 374:
Line 375: protected override void FrameworkInitialize() {
Line 376: this.__BuildControlTree(this);
Line 377: this.FileDependencies = ASP.TestControls_aspx.__fileDependencies;
Line 378: this.EnableViewStateMac = true;
Line 379: this.Request.ValidateInput();
Line 380: }
Line 381:
Line 382: public override int GetTypeHashCode() {
Line 383: return 2057729977;
Line 384: }
Line 385: }
Line 386: }
Line 387:
参看加亮的编码句子。
去除那个注释，然后请求该页，你在C:\WINDOWS\Microsoft.NET\Framework\v1.1.4322\Temporary ASP.NET Files下能找到一个cs文件，内含同样的编码，注意要加
<%@ Page Debug=”true” %>
是否曾经疑惑过DataGrid模板里的Container是什么玩意？哪里也找不到它的定义？看看上面加亮的编码，原来它是个局部变量名！
System.Web.UI.WebControls.DataGridItem Container;
