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意：以下代码请在Firefox 3.5、Chrome 3.0、Safari 4之后的版本中进行测试。IE8的实现方法与其他浏览不同。
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‘ onclick=‘crossDomainRequest()‘ />
- <div id="content"></div>
- <mce:script type="text/javascript"><!--
- 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;
- }
- }
- // --></mce: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/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。
4，IE8 中的实现方法
IE8已经开始支持跨域访问资源了，但是，IE8提供的功能还比较简单，可以进行简单的请求，下面是一个使用的例子：
- <!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‘ onclick=‘crossDomainRequest()‘ />
- <div id="content"></div>
- <mce:script type="text/javascript"><!--
- var xhr = new XDomainRequest();
- var url = ‘http://dotnet.aspx.cc/SimpleCrossSiteRequests.aspx‘;
- function crossDomainRequest() {
- document.getElementById("content").innerHTML = "开始……";
- if (xhr) {
- xhr.open(‘GET‘, url);
- xhr.onload = handler;
- xhr.send();
- } else {
- document.getElementById("content").innerHTML = "不能创建 XDomainRequest";
- }
- }
- function handler(evtXHR) {
- document.getElementById("content").innerHTML = "结果：" + xhr.responseText;
- }
- // --></mce:script>
- </body>
- </html>
另外，IE8的实现方法与其他浏览器不同。更多内容请参考 XDomainRequest 对象，地址是：
http://msdn.microsoft.com/zh-cn/library/cc288060(VS.85).aspx
最后，愿意测试的朋友可以访问这个 http://dotnet.aspx.cc/SimpleCrossSiteRequests.aspx 地址进行“简单请求”的测试，本页面允许任何地址进行跨域访问
AJAX（XMLHttpRequest）进行跨域请求方法详解（三）
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原文地址：http://www.cnblogs.com/love540376/p/5000018.html
