由于要做一個注冊頁面，看到許多網站上都是使用Ajax異步刷新驗證用戶名是否可用的，所以自己也動手做一個小實例
都是簡單的實例，所以直接發代碼 靜態頁面Ajax.html 代碼如下:<html> <head> <title>Ajax</title> <script type="text/javascript"> function loadXMLDoc() { if (document.getElementById("account").value == "") { document.getElementById("accDiv").innerHTML = "用戶名不能為空"; return; } var xmlHttp; if(window.XMLHttpRequest) { // code for IE7+ xmlHttp = new XMLHttpRequest(); } else { // code for IE5/IE6 xmlHttp = new ActiveXObject("Microsoft.XMLHTTP"); } xmlHttp.onreadystatechange = function () { if (xmlHttp.readyState == 4 && xmlHttp.status == 200) { //document.getElementById("myDiv").innerHTML=xmlHttp.responseText; if (xmlHttp.responseText == "true") { document.getElementById("accDiv").innerHTML = "用戶名不可用"; } else { document.getElementById("accDiv").innerHTML = "用戶名可用"; } } } var a = document.getElementById("account").value; // get xmlHttp.open("GET", "validate.aspx?account=" + a + "&random=" + Math.random, true); xmlHttp.send(); } function delData() { document.getElementById("account").value = ""; document.getElementById("accDiv").innerHTML = ""; } </script> </head> <body> <h3>ajax</h3> <table> <tr> <td>賬號：</td><td><input id="account" type="text" onblur="loadXMLDoc();" onfocus="delData();"/></td><td><div id="accDiv"></div></td> </tr> <tr> <td>密碼：</td><td><input id="passwd" type="password" /></td> </tr> <tr> <td>確認密碼：</td><td><input id="vPasswd" type="password" /></td> </tr> <tr> <td>姓名：</td><td><input id="name" type="text" /></td> </tr> </table> </body></html> 在賬號輸入框失去焦點時調用函數 訪問服務器使用的是Get方法，所以在參數處使用了附加隨機碼來避免緩存。 驗證頁面validate.aspx后臺代碼：代碼如下:using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;using System.Configuration;using System.Data.Sql;using System.Data.SqlClient; public partial class Ajax_validate_validate : System.Web.UI.Page{ public SqlConnection conn; protected void Page_Load(object sender, EventArgs e) { Response.Clear(); if (Exists(Request.QueryString["account"])) Response.Write("true"); else Response.Write("false"); Response.End(); } /// <summary> /// 獲取數據庫連接 /// </summary> /// <returns></returns> protected SqlConnection GetConnection() { string str = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString; conn = new SqlConnection(str); return conn; } protected bool Exists(string account) { using (GetConnection()) {新聞熱點
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