4
根据Mozilla Developer Center HTTP access control文章，如果请求的内容类型为application/x-www-form-urlencoded，则跨站点POST请求可以是“简单的” - 即不需要预检。为什么我的跨域POST请求被OPTIONS请求预检？
我没有得到这种行为在Firefox中，我不理解为什么这样。这是我的设置代码：
function makeXDomainRequest(url, method, data) {
var req =
typeof XDomainRequest !== "undefined" ?
new XDomainRequest() : new XMLHttpRequest();
req.open(method || "GET", url, true);
if (typeof req.onload !== "undefined") {
req.onload = onResponseLoad;
req.onerror = onRequestError;
} else {
req.onreadystatechange = onRequestStateChange;
}
if (data && typeof req.setRequestHeader === "function") {
req.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
} else {
// no way to set Content-Type req header in IE's XDomainRequest:
// http://blogs.msdn.com/b/ieinternals/archive/2010/05/13/xdomainrequest-restrictions-limitations-and-workarounds.aspx
}
req.send(data || null);
}
function onResponseLoad() {
alert("Response!\n" + this.responseText);
}
function onRequestError(args) {
alert("Error!");
}
function onRequestStateChange() {
if (this.readyState === 4) {
if (this.status === 200) {
onResponseLoad.apply(this);
} else {
onRequestError.apply(this);
}
}
}
这里就是我ping服务器：
// thanks to http://saltybeagle.com/cors/ for having this demo endpoint:
var URL = "http://ucommbieber.unl.edu/CORS/cors.php";
现在，如果我做一个简单的POST请求 - 在上面的代码发送作为application/x-www-form-urlencoded数据 - 请求在Firefox中通过OPTIONS请求进行预检。在Chrome中未预先指定。运行此之前打开Fiddler看到自己：
makeXDomainRequest(URL, "POST", "name=foobar");
// alerts "Response! Hello CORS [...] You sent a POST request. Your name is foobar"
这里是预检选项提琴手要求（即使我指定的所谓安全Content-Type和没有自定义页眉注意到Access-Control-Request-Method: POST头）：
OPTIONS http://ucommbieber.unl.edu/CORS/cors.php HTTP/1.1
Host: ucommbieber.unl.edu
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.8) Gecko/20100722 Firefox/3.6.8
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 115
Connection: keep-alive
Origin: http://localhost
Access-Control-Request-Method: POST
发生了什么事？这是Firefox中的错误，还是我做错了什么？谢谢！