PHP output gzip compression

<code><span><span>function</span><span>ob_gzip</span><span>(<span>$content</span>)</span>{</span><span>if</span>(!headers_sent()&&extension_loaded(<span>"zlib"</span>)&&strstr(<span>$_SERVER</span>[<span>"HTTP_ACCEPT_ENCODING"</span>],<span>"gzip"</span>)){
        <span>$content</span> = gzencode(<span>$content</span>,<span>9</span>);
        header(<span>"Content-Encoding: gzip"</span>);
        header(<span>"Vary: Accept-Encoding"</span>);
        header(<span>"Content-Length: "</span>.strlen(<span>$content</span>));
    }
    <span>return</span><span>$content</span>;
}
ob_start(<span>'ob_gzip'</span>); <span>//函数名</span><span>echo</span><span>"这是测试字符串这是测试字符串这是测试字符串"</span>;
ob_end_flush();</code>