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AJAX（XMLHttpRequest）进行跨域请求方法详解（三）

2010-07-20 15:57 796 查看

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：

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<!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>

<!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：

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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

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：

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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

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：

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<!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>

<!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。（

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