Asp.net回调技术Callback学习笔记

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.aspx:

001 <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

002

003 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

004 <html xmlns="http://www.w3.org/1999/xhtml">

005 <head runat="server">

006 <title>无标题页</title>

007

008 <script type="text/javascript">

009

010 //向服务器传递参数

011 function DoSearch(){

012 var firstName=document.getElementById("TextBox1").value;

013 CallServer(firstName,"");

014 }

015

016 //得到服务器的数据

017 function ReceiveServerData(txtUserInfo){

018 Results.innerHTML=txtUserInfo;

019 }

020

021 //设置每1秒执行一次

022 setInterval("DoSearch()",1000);

023 </script>

024

025 </head>

026 <body>

027 <form id="form1" runat="server">

028 <div>

029 姓名:<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

030 <br />

031 <span id="Results" style=" width:500px;"></span>

032 </div>

033 </form>

034 </body>

035 </html>

036 [/code]

037 .aspx.cs

038 [code]

039 using System;

040 using System.Collections;

041 using System.Configuration;

042 using System.Data;

043 using System.Web;

044 using System.Web.Security;

045 using System.Web.UI;

046 using System.Web.UI.HtmlControls;

047 using System.Web.UI.WebControls;

048 using System.Web.UI.WebControls.WebParts;

049 using System.Data.SqlClient;

050

051 public partial class _Default : System.Web.UI.Page, ICallbackEventHandler

052 {

053 protected string txtUserInfo;

054

055

056 protected void Page_Load(object sender, EventArgs e)

057 {

058 //获取一个对客户端函数的引用

059 string cbReference = Page.ClientScript.GetCallbackEventReference(this, "arg", "ReceiveServerData", "context");

060 //动态注册回调函数

061 string callbackScript = "function CallServer(arg,context)" + "{" + cbReference + "};";

062 //引发callbackScript

063 Page.ClientScript.RegisterStartupScript(this.GetType(), "CallServer", callbackScript, true);

064 }

065

066 //引发Callback事件处理

067 public void RaiseCallbackEvent(string txtFirstName)

068 {

069 if (txtFirstName != null)

070 {

071 String connString = System.Configuration.ConfigurationManager.ConnectionStrings["sqlserver2008"].ToString();

072

073 SqlConnection conn = new SqlConnection(connString);

074

075 conn.Open();

076

077 SqlCommand comm = new SqlCommand("select * from zzx where [name]=@name", conn);

078

079 comm.Parameters.Add("@name", SqlDbType.VarChar).Value = txtFirstName;

080

081 SqlDataReader reader = comm.ExecuteReader(CommandBehavior.CloseConnection);

082 if (reader.Read())

083 {

084 txtUserInfo = "员工编号:" + reader["id"].ToString() + "<br>";

085 txtUserInfo += "员工姓名:" + reader["name"].ToString() + "<br>";

086 txtUserInfo += "地址:" + reader["address"].ToString() + "<br>";

087 txtUserInfo += "服务器查询时间:" + DateTime.Now.ToString();

088 }

089 else

090 {

091 if (string.IsNullOrEmpty(txtFirstName))

092 {

093 txtUserInfo = "请输入姓名";

094 }

095 else

096 {

097 txtUserInfo = "查无此人";

098 }

099 }

100

101 comm.Dispose();

102 reader.Dispose();

103 conn.Dispose();

104 }

105 }

106

107 //得到回调的结果,返回给客户端

108 public string GetCallbackResult()

109 {

110 return txtUserInfo;

111 }

112

113

114 }

简化版(偷懒一下):

01 <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

03 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

04 <html xmlns="http://www.w3.org/1999/xhtml">

05 <head runat="server">

06 <title>无标题页</title>

08 <script type="text/javascript">

09 function OnCallBack(txtUserInfo,context){

10 Results.innerHTML=txtUserInfo;

11 }

12 </script>

14 </head>

15 <body>

16 <form id="form1" runat="server">

17 <div>

18 姓名:<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

19 <input id="Button2" type="button" value="button"

20 onclick="<%=Page.ClientScript.GetCallbackEventReference(this, "document.getElementById('TextBox1').value", "OnCallBack",null)%>" />

21 <br />

22 <span id="Results" style="pink; width: 500;"></span>

23 </div>

24 </form>

25 </body>

26 </html>

27 .aspx.cs

29 using System;

30 using System.Collections;

31 using System.Configuration;

32 using System.Data;

33 using System.Web;

34 using System.Web.Security;

35 using System.Web.UI;

36 using System.Web.UI.HtmlControls;

37 using System.Web.UI.WebControls;

38 using System.Web.UI.WebControls.WebParts;

39 using System.Data.SqlClient;

40 using System.Text;

41 public partial class _Default : System.Web.UI.Page, ICallbackEventHandler

42 {

43 protected StringBuilder txtUserInfo;

45 protected void Page_Load(object sender, EventArgs e)

46 {

48 }

50 public string GetCallbackResult()

51 {

52 return txtUserInfo.ToString();

53 }

55 public void RaiseCallbackEvent(string txtFirstName)

56 {

57 txtUserInfo = new StringBuilder();

58 String connString = ConfigurationManager.ConnectionStrings["sqlserver2008"].ToString();

59 SqlConnection conn = new SqlConnection(connString);

60 conn.Open();

61 SqlCommand comm = new SqlCommand("select * from zzx where [name]=@name", conn);

62 comm.Parameters.Add("@name", SqlDbType.VarChar).Value = txtFirstName;

63 SqlDataReader reader = comm.ExecuteReader(CommandBehavior.CloseConnection);

64 if (reader.Read())

65 {

66 txtUserInfo.Append("员工编号:" + reader["id"].ToString() + "<br>");

67 txtUserInfo.Append("员工姓名:" + reader["name"].ToString() + "<br>");

68 txtUserInfo.Append("地址:" + reader["address"].ToString() + "<br>");

69 txtUserInfo.Append("查询时间:" + DateTime.Now.ToString());

70 }

71 else

72 {

73 if (txtFirstName == string.Empty)

74 {

75 txtUserInfo.Append("请输入姓名");

76 }

77 else

78 {

79 txtUserInfo.Append("查无此人");

80 }

81 reader.Dispose();

82 comm.Dispose();

83 conn.Dispose();

84 }

85 }

86 }

示例3:

01 <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default3.aspx.cs" Inherits="Default3" %>

03 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

05 <html xmlns="http://www.w3.org/1999/xhtml">

06 <head runat="server">

07 <title>无标题页</title>

08 <script type="text/javascript">

09 //客户端执行的方法

10 //下面的方法是接收并处理服务器方法返回的结果

11 function Success(args,context){

12 message.innerHTML=args;

13 }

15 //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

16 function Error(){

17 message.innerHTML="发生了异常!";

18 }

19 </script>

20 </head>

21 <body>

22 <form id="form1" runat="server">

23 <div>

24 用户名:<input type="text" id="txtUserName" onblur="CallServerMethod(txtUserName.value,null)" />

25 <span id="message"></span>

26 <br />

27 密码:<input type="password" size="10" maxlength="20" id="txtPwd" />

28 </div>

29 </form>

30 </body>

31 </html>

32 [code]

33 public partial class Default3 : System.Web.UI.Page,ICallbackEventHandler //实现ICallbackEventHandler接口

34 {

36 String result = String.Empty;

38 protected void Page_Load(object sender, EventArgs e)

39 {

40 //获取当前页的ClientScriptManager的引用

41 ClientScriptManager csm = Page.ClientScript;

42 /*获取回调的引用.会在客户端生成WebForm_DoCallback方法,

43 * 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

44 到客户端*/

45 /*注意这里的"Success"和Error两个字符串分别是客户端代码中

46 *定义的两个javascript函数*/

47 //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

48 String reference = csm.GetCallbackEventReference(this, "args", "Success", "", "Error", true);

49 String callbackScript = "function CallServerMethod(args,context){\n"+

50 reference+";\n }";

51 //向当前页面注册javascript脚本代码

52 csm.RegisterClientScriptBlock(this.GetType(), "CallServerMethod",callbackScript,true);

53 }

55 #region ICallbackEventHandler 成员

57 /// <summary>

58 /// 返回回调方法执行结果的方法

59 /// </summary>

60 public string GetCallbackResult()

61 {

62 return result;

63 }

65 /// <summary>

66 /// 在服务器端运行回调方法

67 /// </summary>

68 public void RaiseCallbackEvent(string eventArgument)

69 {

70 if (eventArgument.ToLower().IndexOf("admin")!=-1)

71 {

72 result =eventArgument+ "不能作为用户注册.";

73 }

74 else

75 {

76 result = eventArgument + "可以注册.";

77 }

78 }

80 #endregion

81 }

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