XHR无法加载 <URL> 。请求的资源上不存在“ Access-Control-Allow-Origin”标头

Question

I'm trying to execute a cross-domain AJAX request using JQuery. 我正在尝试使用JQuery执行跨域AJAX请求。 The server is executing a CGI file scripted in Python. 服务器正在执行使用Python编写脚本的CGI文件。 I've tried adding CORS support to the server but it doesn't appear to be working, saying: 我尝试将CORS支持添加到服务器，但是它似乎不起作用，说：

XMLHttpRequest cannot load http://<URL>.cgi. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin <Other-URL> is therefore not allowed access.

The JQuery AJAX request is: JQuery AJAX请求是：

$.ajax({
    type: "POST",
    url: "http://<URL>.cgi",
})
.done(function(msg) {
    alert(msg);
});

and the server script is: 服务器脚本是：

import os
import cgi
import cgitb; cgitb.enable()
import sys
import mysql.connector
from mysql.connector import errorcode

form = cgi.FieldStorage() 

Username = form.getvalue('username')
Email    = form.getvalue('email')
Password = form.getvalue('password')

print ("Content-Type: text/html")
print ("Access-Control-Allow-Origin: *")

print("<\h2>Welcome, your credentials are as follows Username: %s Email: %s Password: %s </h2>" % (Username, Email, Password))  
print ("""
<html>
<head>
</head>
<body>
""")

try:
    cnx = mysql.connector.connect(user='xxxxxx', password='xxxxxxx', host='127.0.0.1', database='xxxxxxx')
    cursor = cnx.cursor()
    #cursor.execute("INSERT INTO `user_information` (`User_ID`, `Email`, `Username`, `Password`) VALUES (NULL, %s, %s, %s)", (Email, Username, Password))
    cursor.execute("SELECT * FROM  `user_information` LIMIT 0 , 30")
    data = cursor.fetchall()
    print(data)
    cnx.commit()
    cursor.close()
    cnx.close()
except mysql.connector.Error as err:
    print("Something went wrong: {}".format(err))

print ("""
</body>
</html>
""")

Answer 1

Try placing print "Access-Control-Allow-Origin: * at the top of your script instead of in the output. This finally solved it for me and didn't interfere with the script execution. 尝试将print "Access-Control-Allow-Origin: *放在脚本的顶部而不是输出的顶部。这最终为我解决了该问题，并且不干扰脚本的执行。

My code: 我的代码：

#!/usr/bin/env python2.7
# -*- coding: UTF-8 -*-
print "Access-Control-Allow-Origin: *"

import os
import cgi
etc...

Of course, you will probably want to whitelist a specific set of domains, instead of allowing all with *. 当然，您可能希望将一组特定的域列入白名单，而不是使用*来全部包含。

Answer 2

Your print commands are not creating a valid HTTP header . 您的打印命令没有创建有效的HTTP标头。 Instead of placing just placing 而不是仅仅放置

print ("Access-Control-Allow-Origin: *")

there you need to create the required CR-LF line endings and the two consecutive CR-LF to end the header. 在那里，您需要创建所需的CR-LF行尾，并创建两个连续的CR-LF以结束标题。 Also beware the automatic linefeed of the print command. 还要注意打印命令的自动换行。 This should work: 这应该工作：

print ("Content-Type: text/html\r\n"),
print ("Access-Control-Allow-Origin: *\r\n\r\n"),

XHR无法加载 <URL> 。请求的资源上不存在“ Access-Control-Allow-Origin”标头

问题描述

2 个解决方案

解决方案1
0 2014-11-09 23:03:53

解决方案2
0 2018-05-17 16:53:41

XHR无法加载 <URL> 。 请求的资源上不存在“ Access-Control-Allow-Origin”标头

问题描述

2 个解决方案

解决方案1 0 2014-11-09 23:03:53

解决方案2 0 2018-05-17 16:53:41

XHR无法加载 <URL> 。请求的资源上不存在“ Access-Control-Allow-Origin”标头

解决方案1
0 2014-11-09 23:03:53

解决方案2
0 2018-05-17 16:53:41