(PHP 5 >= 5.4.0, PHP 7)
header_register_callback — Call a header function
Registers a function that will be called when PHP starts sending output.
The callback is executed just after PHP prepares all
headers to be sent, and before any other output is sent, creating a window
to manipulate the outgoing headers before being sent.
callbackFunction called just before the headers are sent. It gets no parameters and the return value is ignored.
成功时返回 TRUE， 或者在失败时返回 FALSE。
Example #1 header_register_callback() example
<?php
header('Content-Type: text/plain');
header('X-Test: foo');
function foo() {
foreach (headers_list() as $header) {
if (strpos($header, 'X-Powered-By:') !== false) {
header_remove('X-Powered-By');
}
header_remove('X-Test');
}
}
$result = header_register_callback('foo');
echo "a";
?>
以上例程的输出类似于：
Content-Type: text/plain a
header_register_callback() is executed just as the headers are about to be sent out, so any output from this function can break output.
Note:
数据头只会在SAPI支持时得到处理和输出。