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AJAX(XMLHttpRequest)进行跨域请求方法详解(三)

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:

<!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' nclick='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>

点击“开始测试”,我们可以检测到下面的请求执行过程:

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 是会随请求一起发送的。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:

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/CrossDomain
Ajax/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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