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Asp.net回调技术Callback学习笔记

时间：2021-07-01 10:21:17 帮助过：15人阅读

.aspx:

  1. <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %> 
  2. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 
  3. <html xmlns="http://www.w3.org/1999/xhtml"> 
  4. <head runat="server"> 
  5. <title>无标题页</title> 
  6. <script type="text/javascript"> 
  7. //向服务器传递参数 
  8. function DoSearch(){ 
  9. var firstName=document.getElementById("TextBox1").value; 
  10. CallServer(firstName,""); 
  11. } 
  12. //得到服务器的数据 
  13. function ReceiveServerData(txtUserInfo){ 
  14. Results.innerHTML=txtUserInfo; 
  15. } 
  16. //设置每1秒执行一次 
  17. setInterval("DoSearch()",1000); 
  18. </script> 
  19. </head> 
  20. <body> 
  21. <form id="form1" runat="server"> 
  22. <div> 
  23. 姓名:<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox> 
  24. <br /> 
  25. <span id="Results" style=" width:500px;"></span> 
  26. </div> 
  27. </form> 
  28. </body> 
  29. </html>
  30. [/code]
  31. .aspx.cs
  32. [code]
  33. using System; 
  34. using System.Collections; 
  35. using System.Configuration; 
  36. using System.Data; 
  37. using System.Web; 
  38. using System.Web.Security; 
  39. using System.Web.UI; 
  40. using System.Web.UI.HtmlControls; 
  41. using System.Web.UI.WebControls; 
  42. using System.Web.UI.WebControls.WebParts; 
  43. using System.Data.SqlClient; 
  44. public partial class _Default : System.Web.UI.Page, ICallbackEventHandler 
  45. { 
  46. protected string txtUserInfo; 
  47. protected void Page_Load(object sender, EventArgs e) 
  48. { 
  49. //获取一个对客户端函数的引用 
  50. string cbReference = Page.ClientScript.GetCallbackEventReference(this, "arg", "ReceiveServerData", "context"); 
  51. //动态注册回调函数 
  52. string callbackScript = "function CallServer(arg,context)" + "{" + cbReference + "};"; 
  53. //引发callbackScript 
  54. Page.ClientScript.RegisterStartupScript(this.GetType(), "CallServer", callbackScript, true); 
  55. } 
  56. //引发Callback事件处理 
  57. public void RaiseCallbackEvent(string txtFirstName) 
  58. { 
  59. if (txtFirstName != null) 
  60. { 
  61. String connString = System.Configuration.ConfigurationManager.ConnectionStrings["sqlserver2008"].ToString(); 
  62. SqlConnection conn = new SqlConnection(connString); 
  63. conn.Open(); 
  64. SqlCommand comm = new SqlCommand("select * from zzx where [name]=@name", conn); 
  65. comm.Parameters.Add("@name", SqlDbType.VarChar).Value = txtFirstName; 
  66. SqlDataReader reader = comm.ExecuteReader(CommandBehavior.CloseConnection); 
  67. if (reader.Read()) 
  68. { 
  69. txtUserInfo = "员工编号:" + reader["id"].ToString() + "<br>"; 
  70. txtUserInfo += "员工姓名:" + reader["name"].ToString() + "<br>"; 
  71. txtUserInfo += "地址:" + reader["address"].ToString() + "<br>"; 
  72. txtUserInfo += "服务器查询时间:" + DateTime.Now.ToString(); 
  73. } 
  74. else 
  75. { 
  76. if (string.IsNullOrEmpty(txtFirstName)) 
  77. { 
  78. txtUserInfo = "请输入姓名"; 
  79. } 
  80. else 
  81. { 
  82. txtUserInfo = "查无此人"; 
  83. } 
  84. } 
  85. comm.Dispose(); 
  86. reader.Dispose(); 
  87. conn.Dispose(); 
  88. } 
  89. } 
  90. //得到回调的结果,返回给客户端 
  91. public string GetCallbackResult() 
  92. { 
  93. return txtUserInfo; 
  94. } 
  95. }

简化版(偷懒一下):

  1. <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %> 
  2. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 
  3. <html xmlns="http://www.w3.org/1999/xhtml"> 
  4. <head runat="server"> 
  5. <title>无标题页</title> 
  6. <script type="text/javascript"> 
  7. function OnCallBack(txtUserInfo,context){ 
  8. Results.innerHTML=txtUserInfo; 
  9. } 
  10. </script> 
  11. </head> 
  12. <body> 
  13. <form id="form1" runat="server"> 
  14. <div> 
  15. 姓名:<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox> 
  16. <input id="Button2" type="button" value="button" 
  17. onclick="<%=Page.ClientScript.GetCallbackEventReference(this, "document.getElementById('TextBox1').value", "OnCallBack",null)%>" /> 
  18. <br /> 
  19. <span id="Results" style="pink; width: 500;"></span> 
  20. </div> 
  21. </form> 
  22. </body> 
  23. </html>
  24. .aspx.cs
  25. using System; 
  26. using System.Collections; 
  27. using System.Configuration; 
  28. using System.Data; 
  29. using System.Web; 
  30. using System.Web.Security; 
  31. using System.Web.UI; 
  32. using System.Web.UI.HtmlControls; 
  33. using System.Web.UI.WebControls; 
  34. using System.Web.UI.WebControls.WebParts; 
  35. using System.Data.SqlClient; 
  36. using System.Text; 
  37. public partial class _Default : System.Web.UI.Page, ICallbackEventHandler 
  38. { 
  39. protected StringBuilder txtUserInfo; 
  40. protected void Page_Load(object sender, EventArgs e) 
  41. { 
  42. } 
  43. public string GetCallbackResult() 
  44. { 
  45. return txtUserInfo.ToString(); 
  46. } 
  47. public void RaiseCallbackEvent(string txtFirstName) 
  48. { 
  49. txtUserInfo = new StringBuilder(); 
  50. String connString = ConfigurationManager.ConnectionStrings["sqlserver2008"].ToString(); 
  51. SqlConnection conn = new SqlConnection(connString); 
  52. conn.Open(); 
  53. SqlCommand comm = new SqlCommand("select * from zzx where [name]=@name", conn); 
  54. comm.Parameters.Add("@name", SqlDbType.VarChar).Value = txtFirstName; 
  55. SqlDataReader reader = comm.ExecuteReader(CommandBehavior.CloseConnection); 
  56. if (reader.Read()) 
  57. { 
  58. txtUserInfo.Append("员工编号:" + reader["id"].ToString() + "<br>"); 
  59. txtUserInfo.Append("员工姓名:" + reader["name"].ToString() + "<br>"); 
  60. txtUserInfo.Append("地址:" + reader["address"].ToString() + "<br>"); 
  61. txtUserInfo.Append("查询时间:" + DateTime.Now.ToString()); 
  62. } 
  63. else 
  64. { 
  65. if (txtFirstName == string.Empty) 
  66. { 
  67. txtUserInfo.Append("请输入姓名"); 
  68. } 
  69. else 
  70. { 
  71. txtUserInfo.Append("查无此人"); 
  72. } 
  73. reader.Dispose(); 
  74. comm.Dispose(); 
  75. conn.Dispose(); 
  76. }
  77. } 
  78. }

示例3:

  1. <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default3.aspx.cs" Inherits="Default3" %> 
  2. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 
  3. <html xmlns="http://www.w3.org/1999/xhtml"> 
  4. <head runat="server"> 
  5. <title>无标题页</title> 
  6. <script type="text/javascript"> 
  7. //客户端执行的方法 
  8. //下面的方法是接收并处理服务器方法返回的结果 
  9. function Success(args,context){ 
  10. message.innerHTML=args; 
  11. } 
  12. //下面的方式是当接收服务器方法处理的结果发生异常时调用的方法 
  13. function Error(){ 
  14. message.innerHTML="发生了异常!"; 
  15. } 
  16. </script> 
  17. </head> 
  18. <body> 
  19. <form id="form1" runat="server"> 
  20. <div> 
  21. 用户名:<input type="text" id="txtUserName" onblur="CallServerMethod(txtUserName.value,null)" /> 
  22. <span id="message"></span> 
  23. <br /> 
  24. 密码:<input type="password" size="10" maxlength="20" id="txtPwd" /> 
  25. </div> 
  26. </form> 
  27. </body> 
  28. </html>
  29. [code]
  30. public partial class Default3 : System.Web.UI.Page,ICallbackEventHandler //实现ICallbackEventHandler接口 
  31. { 
  32. String result = String.Empty; 
  33. protected void Page_Load(object sender, EventArgs e) 
  34. { 
  35. //获取当前页的ClientScriptManager的引用 
  36. ClientScriptManager csm = Page.ClientScript; 
  37. /*获取回调的引用.会在客户端生成WebForm_DoCallback方法, 
  38. * 调用它来达到异步调用.这个方法是微软写的方法,会被发送 
  39. 到客户端*/ 
  40. /*注意这里的"Success"和Error两个字符串分别是客户端代码中 
  41. *定义的两个javascript函数*/ 
  42. //下面的方法最后一个参数的意义:true表示执行异步回调,false标志执行同步回调 
  43. String reference = csm.GetCallbackEventReference(this, "args", "Success", "", "Error", true); 
  44. String callbackScript = "function CallServerMethod(args,context){\n"+ 
  45. reference+";\n }"; 
  46. //向当前页面注册javascript脚本代码 
  47. csm.RegisterClientScriptBlock(this.GetType(), "CallServerMethod",callbackScript,true); 
  48. } 
  49. #region ICallbackEventHandler 成员 
  50. /// <summary> 
  51. /// 返回回调方法执行结果的方法 
  52. /// </summary> 
  53. public string GetCallbackResult() 
  54. { 
  55. return result; 
  56. } 
  57. /// <summary> 
  58. /// 在服务器端运行回调方法 
  59. /// </summary> 
  60. public void RaiseCallbackEvent(string eventArgument) 
  61. { 
  62. if (eventArgument.ToLower().IndexOf("admin")!=-1) 
  63. { 
  64. result =eventArgument+ "不能作为用户注册."; 
  65. } 
  66. else 
  67. { 
  68. result = eventArgument + "可以注册."; 
  69. } 
  70. } 
  71. #endregion 
  72. }

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