都是简单的实例，所以直接发代码
静态页面Ajax.html
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1
2
3 Ajax
4 <script type="text/java script">
5 function loadXMLDoc() {
6 if (document.getElementById("account").value == "") {
7 document.getElementById("accDiv").innerHTML = "用户名不能为空";
8 return;
9 }
10 var xmlHttp;
11 if(window.XMLHttpRequest) { // code for IE7+
12 xmlHttp = new XMLHttpRequest();
13 }
14 else { // code for IE5/IE6
15 xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
16 }
17
18 xmlHttp.onreadystatechange = function () {
19 if (xmlHttp.readyState == 4 && xmlHttp.status == 200) {
20 //document.getElementById("myDiv").innerHTML=xmlHttp.responseText;
21 if (xmlHttp.responseText == "true") {
22 document.getElementById("accDiv").innerHTML = "用户名不可用";
23 }
24 else {
25 document.getElementById("accDiv").innerHTML = "用户名可用";
26 }
27 }
28 }
29 var a = document.getElementById("account").value;
30 // get
31 xmlHttp.open("GET", "validate.aspx account=" + a + "&random=" + Math.random, true);
32 xmlHttp.send();
33 }
34 function delData() {
35 document.getElementById("account").value = "";
36 document.getElementById("accDiv").innerHTML = "";
37 }
38
39
40
41
ajax
42
| 账号： | ||
| 密码： | ||
| 确认密码： | ||
| 姓名： |
56
57
58
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在账号输入框失去焦点时调用函数
访问服务器使用的是Get方法，所以在参数处使用了附加随机码来避免缓存。
验证页面validate.aspx后台代码：
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1 using System;
2 using System.Collections.Generic;
3 using System.Linq;
4 using System.Web;
5 using System.Web.UI;
6 using System.Web.UI.WebControls;
7 using System.Configuration;
8 using System.Data.Sql;
9 using System.Data.SqlClient;
10
11 public partial class Ajax_validate_validate : System.Web.UI.Page
12 {
13 public SqlConnection conn;
14
15 protected void Page_Load(object sender, EventArgs e)
16 {
17 Response.Clear();
18 if (Exists(Request.QueryString["account"]))
19 Response.Write("true");
20 else
21 Response.Write("false");
22 Response.End();
23 }
24 ///
25 /// 获取
数据库连接
26 ///
27 ///
28 protected SqlConnection GetConnection()
29 {
30 string str = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
31 conn = new SqlConnection(str);
32 return conn;
33 }
34 protected bool Exists(string account)
35 {
36 using (GetConnection())
37 {
38 try
39 {
40 conn.Open();
41 string sqlStr = "select count(*) from userinfo where account='" + account + "'";
42 SqlCommand cmd = new SqlCommand(sqlStr, conn);
43 int row = Convert.ToInt32(cmd.ExecuteScalar()