日期:2014-05-16 浏览次数:20584 次
HTML代码如下:
LoginValidate.aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="LoginValidate.aspx.cs" Inherits="LoginValidate" %> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server"> <title>验证用户名是否存在</title> <script type="text/javascript"> var xmlHttp; function createXMLHttpRequest() { if(window.ActiveXObject) { xmlHttp = new ActiveXObject("Microsoft.XMLHTTP"); } else if(window.XMLHttpRequest) { xmlHttp = new XMLHttpRequest(); } } //处理方法 function CheckUserName() { createXMLHttpRequest(); var url= "LoginValidate.ashx?username="+document.getElementById("username").value; xmlHttp.open("GET",url,true); xmlHttp.onreadystatechange=ShowResult; xmlHttp.send(null); //document.getElementById("Msg").innerHTML=''; } //回调方法 function ShowResult() { if(xmlHttp.readyState==4) { if(xmlHttp.status==200) { document.getElementById("Msg").innerHTML=xmlHttp.responseText; } } } </script> </head> <body> <form id="form1" runat="server"> <div> <table style="width: 487px"> <tr> <td style="width: 70px"> 用户名:</td> <td style="width: 231px"><input id="username" type="text" /> <input id="Button1" type="button" value="button" onclick="CheckUserName();" /></td> <td id="Msg"></td> </tr> <tr> <td style="width: 70px"> </td> <td style="width: 231px"> </td> <td> </td> </tr> </table> </div> </form> </body> </html>
?
服务器端代码如下:(这里我是用的临时处理文件.ashx)
LoginValidate.ashx
<%@ WebHandler Language="C#" Class="LoginValidate" %> using System; using System.Web; using System.Data; using System.Data.SqlClient; public class LoginValidate : IHttpHandler { public void ProcessRequest (HttpContext context) { context.Response.ContentType = "text/plain"; string username = context.Request.QueryString["username"].ToString(); string strSQL = "select username from users where username='" + username + "'"; if (ReDataSet(strSQL).Tables[0].Rows.Count > 0) { context.Response.Write("该用户已经有人使用!"); } else { context.Response.Write("恭喜你!"+username+"可以使用!"); } System.Threading.Thread.Sleep(3000); } //数据库连接字符串 public static string strCon = "Data Source=.;database=exam;uid=sa;pwd=;"; /// <summary> /// 执行SQL语句,返回DataSet /// </summary> /// <param name="strSQL"></param> /// <returns></returns> public DataSet ReDataSet(string strSQL) { SqlConnection con = new SqlConnection(strCon); try { con.Open(); SqlDataAdapter da = new SqlDataAdapter(strSQL, con); DataSet ds = new DataSet(); da.Fill(ds); return ds; } catch (Exception ex) { throw new Exception(ex.Message); } finally { con.Close(); } } /// <summary> /// 不重复调用 /// </summary> public bool IsReusable { get { return false; } } }
?