利用CORS实现POST方式跨域请求数据

CORS全名Cross-Origin Resource Sharing，顾名思义：跨域分享资源，这是W3C制定的跨站资源分享标准。

目前包括IE10+、chrome、safari、FF都提供了XMLHttpRequest对象对该标准的支持，在更老的IE8中则提供了xDomainRequest对象，部分实现了该标准；

下面是创建request对象的代码：

var url = "http://www.111com.net /1.php";

if (XMLHttpRequest) {
    var req = new XMLHttpRequest();
    // 利用withCredentials属性来判断是否支持跨域请求
    if (!("withCredentials" in req)) { // w3c先行
        if (window.XDomainRequest) {
            req = new XDomainRequest();
        }
    }
    req.open('POST', url, true);
    req.onload = function (data) {
        alert(this.responseText);
    };
    req.send();
}

注意xDomainRequest对象只支持http和https协议

在利用XMLHttpRequest对象发POST请求前会发一个options嗅探来确定是否有跨域请求的权限；同时在header头上带上Origin信息来指示来源网站信息，服务器响应时需要带上Access-Control-Allow-Origin头的值是否和Origin信息相匹配。

header("Access-Control-Allow-Origin: http://localhost"); // *为全部域名

CORS的缺点是你必须能控制服务器端的权限，允许你跨域访问

设置CORS实现跨域请求

一、使用php代码实现

#
# CORS config for php
# Code by anrip[mail@anrip.com]
#
 
function make_cors($origin = '*') {
 
    $request_method = $_SERVER['REQUEST_METHOD'];
 
    if ($request_method === 'OPTIONS') {
 
        header('Access-Control-Allow-Origin:'.$origin);
        header('Access-Control-Allow-Credentials:true');
        header('Access-Control-Allow-Methods:GET, POST, OPTIONS');
 
        header('Access-Control-Max-Age:1728000');
        header('Content-Type:text/plain charset=UTF-8');
        header('Content-Length: 0',true);
 
        header('status: 204');
        header('HTTP/1.0 204 No Content');
 
    }
 
    if ($request_method === 'POST') {
 
        header('Access-Control-Allow-Origin:'.$origin);
        header('Access-Control-Allow-Credentials:true');
        header('Access-Control-Allow-Methods:GET, POST, OPTIONS');
 
    }
 
    if ($request_method === 'GET') {
 
        header('Access-Control-Allow-Origin:'.$origin);
        header('Access-Control-Allow-Credentials:true');
        header('Access-Control-Allow-Methods:GET, POST, OPTIONS');
 
    }
 
}

二、使用nginx配置实现

# CORS config for nginx
# Code by anrip[mail@anrip.com]
#
 
location / {
 
    set $origin '*';
 
    if ($request_method = 'OPTIONS') {
 
        add_header 'Access-Control-Allow-Origin' $origin;
 
        #
        # Om nom nom cookies
        #
        add_header 'Access-Control-Allow-Credentials' 'true';
        add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
 
        #
        # Custom headers and headers various browsers *should* be OK with but aren't
        #
        add_header 'Access-Control-Allow-Headers' 'DNT,X-Mx-ReqToken,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type';
 
        #
        # Tell client that this pre-flight info is valid for 20 days
        #
        add_header 'Access-Control-Max-Age' 1728000;
        add_header 'Content-Type' 'text/plain charset=UTF-8';
        add_header 'Content-Length' 0;
 
        return 204;
 
    }
 
    if ($request_method = 'POST') {
 
        add_header 'Access-Control-Allow-Origin' $origin;
        add_header 'Access-Control-Allow-Credentials' 'true';
        add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
        add_header 'Access-Control-Allow-Headers' 'DNT,X-Mx-ReqToken,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type';
 
    }
 
    if ($request_method = 'GET') {
 
        add_header 'Access-Control-Allow-Origin' $origin;
        add_header 'Access-Control-Allow-Credentials' 'true';
        add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
        add_header 'Access-Control-Allow-Headers' 'DNT,X-Mx-ReqToken,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type';
 
    }
 
}