http://dotnet.aspx.cc/article/3e52138f-17ba-479a-84d6-765411e5a7fe/read.aspx

AJAX（XMLHttpRequest）进行跨域请求方法详解（三）

作者：孟宪会阅读：1905 发表于：2010-01-11 09:55:53

3，带验证信息的请求
身份验证是Web开发中经常遇到的问题，在跨域请求中，默认情况下是不发送验证信息的。要想发送验证信息，需要进行withCredentials 属性，下面就是一个简单请求的例子：

HTML 代码<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
  <title>孟宪会之AJAX跨域请求测试</title>
</head>
<body>
  <input type='button' value='开始测试' onclick='crossDomainRequest()' />
  <div id="content"></div>

  <script type="text/javascript">
    //<![CDATA[
    var xhr = new XMLHttpRequest();
    var url = 'http://dotnet.aspx.cc/RequestsWithCredentials.aspx';
    function crossDomainRequest() {
      document.getElementById("content").innerHTML = "开始进行请求……";
      if (xhr) {
        xhr.open('GET', url, true);
        xhr.onreadystatechange = handler;
        xhr.withCredentials = "true";
        xhr.send();
      } else {
        document.getElementById("content").innerHTML = "不能创建 XMLHttpRequest。";
      }
    }
    function handler(evtXHR) {
      if (xhr.readyState == 4) {
        if (xhr.status == 200) {
          var response = xhr.responseText;
          document.getElementById("content").innerHTML = "结果：" + response;
        } else {
          document.getElementById("content").innerHTML += "<br/>执行状态 status：" + xhr.status;
        }
      }
      else {
        document.getElementById("content").innerHTML += "<br/>执行状态 readyState：" + xhr.readyState;
      }
    }
    //]]>
  </script>

</body>
</html>

在服务器端，我编写如下的代码，通过 Cookie 记录按钮点击的次数：

ASPX 代码<%@ Page Language="C#" %>

<script runat="server">
  protected void Page_Load(object sender, EventArgs e)
  {
    if (Request.HttpMethod.Equals("GET"))
    {
      Response.AddHeader("Access-Control-Allow-Origin", "http://www.meng_xian_hui.com:801");
      Response.AddHeader("Access-Control-Allow-Credentials", "true");
      Response.Cache.SetCacheability(HttpCacheability.NoCache);
      Response.Expires = -1;
      int visit = 1;
      if (Request.Cookies["visit"] != null)
      {
        visit = Convert.ToInt32(Request.Cookies["visit"].Value) + 1;
      }
      HttpCookie cookie = new HttpCookie("visit", visit.ToString());
      cookie.Expires = DateTime.Now.AddSeconds(30);
      Response.SetCookie(cookie);
      Response.Write(visit.ToString());
    }
    else if (Request.HttpMethod.Equals("OPTIONS"))
    {
      //可以根据Origin进行更多检测

      //通知客户端允许预检请求。并设置缓存时间
      Response.ClearContent();
      Response.AddHeader("Access-Control-Allow-Origin", "http://www.meng_xian_hui.com:801");
      Response.AddHeader("Access-Control-Allow-Methods", "GET, OPTIONS");
      Response.AddHeader("Access-Control-Allow-Credentials", "true");
      Response.AddHeader("Access-Control-Max-Age", "30");
      //此过程无需返回数据
      Response.End();
    }
    else
    {
      Response.StatusCode = 401;
    }
  }
</script>

点击“开始测试”，我们可以检测到下面的请求执行过程：

HTML 代码GET /RequestsWithCredentials.aspx HTTP/1.1
Host: dotnet.aspx.cc
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.2; zh-CN; rv:1.9.1.7) Gecko/20091221 Firefox/3.5.7 (.NET CLR 3.5.30729)
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: zh-cn,zh;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: GB2312,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive
Referer: http://www.meng_xian_hui.com:801/CrossDomainAjax/RequestsWithCredentials.html
Origin: http://www.meng_xian_hui.com:801

HTTP/1.x 200 OK
Date: Sun, 10 Jan 2010 14:12:26 GMT
Server: Microsoft-IIS/6.0
X-Powered-By: ASP.NET
X-AspNet-Version: 2.0.50727
Access-Control-Allow-Origin: http://www.meng_xian_hui.com:801
Access-Control-Allow-Credentials: true
Set-Cookie: ASP.NET_SessionId=fn2zf0zq1cuwgf45fm5fw145; path=/; HttpOnly
Set-Cookie: visit=1; expires=Sun, 10-Jan-2010 14:12:56 GMT; path=/
Cache-Control: no-cache
Pragma: no-cache
Expires: -1
Content-Type: text/html; charset=utf-8
Content-Length: 1

从上面的响应中可以看出，Cookie 是会随响应一起发送的。如果我们多次点击测试按钮，则可以看到请求和响应的结果是这样的：

HTML 代码GET /RequestsWithCredentials.aspx HTTP/1.1
Host: dotnet.aspx.cc
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.2; zh-CN; rv:1.9.1.7) Gecko/20091221 Firefox/3.5.7 (.NET CLR 3.5.30729)
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: zh-cn,zh;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: GB2312,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive
Referer: http://www.meng_xian_hui.com:801/CrossDomainAjax/RequestsWithCredentials.html
Origin: http://www.meng_xian_hui.com:801
Cookie: ASP.NET_SessionId=fn2zf0zq1cuwgf45fm5fw145; visit=2

HTTP/1.x 200 OK
Date: Sun, 10 Jan 2010 14:13:58 GMT
Server: Microsoft-IIS/6.0
X-Powered-By: ASP.NET
X-AspNet-Version: 2.0.50727
Access-Control-Allow-Origin: http://www.meng_xian_hui.com:801
Access-Control-Allow-Credentials: true
Set-Cookie: visit=3; expires=Sun, 10-Jan-2010 14:14:28 GMT; path=/
Cache-Control: no-cache
Pragma: no-cache
Expires: -1
Content-Type: text/html; charset=utf-8
Content-Length: 1

注意 Cookie: ASP.NET_SessionId=fn2zf0zq1cuwgf45fm5fw145; visit=2 这一行，访问计数器已经被一起发送到服务器。

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AJAX（XMLHttpRequest）进行跨域请求方法详解

AJAX（XMLHttpRequest）进行跨域请求方法详解（三）

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