PHP Ajax 跨域问题最佳解决方案

<span>XMLHttpRequest</span><span> cannot load http</span><span>:</span><span>//server.runoob.com/server.php. No 'Access-Control-Allow-Origin' header is present on the requested resource.Origin 'http://client.runoob.com' is therefore not allowed access.</span>

<p>1、允许单个域名访问</p><p>指定某域名（http://client.runoob.com）跨域访问，则只需在http://server.runoob.com/server.php文件头部添加如下代码：</p><p><span>立即学习</span>“<a href="https://pan.quark.cn/s/7fc7563c4182" style="text-decoration: underline !important; color: blue; font-weight: bolder;" rel="nofollow" target="_blank">PHP免费学习笔记（深入）</a>”；</p>
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                <pre class="brush:php;toolbar:false;"><span>header</span><span>(</span><span>'Access-Control-Allow-Origin:http://client.runoob.com'</span><span>);</span>

<span>$origin </span><span>=</span><span> isset</span><span>(</span><span>$_SERVER</span><span>[</span><span>'HTTP_ORIGIN'</span><span>])?</span><span> $_SERVER</span><span>[</span><span>'HTTP_ORIGIN'</span><span>]</span><span>:</span><span>''</span><span>;</span><span>$allow_origin </span><span>=</span><span> array</span><span>(</span><span>'http://client1.runoob.com'</span><span>,</span><span>'http://client2.runoob.com'</span><span>);</span><span>if</span><span>(</span><span>in_array</span><span>(</span><span>$origin</span><span>,</span><span> $allow_origin</span><span>)){</span><span>    header</span><span>(</span><span>'Access-Control-Allow-Origin:'</span><span>.</span><span>$origin</span><span>);</span><span>}</span>

<span>header</span><span>(</span><span>'Access-Control-Allow-Origin:*'</span><span>);</span>