让我们看看我是否可以解释一下自己。如果要从服务器返回的内容为空，我需要返回默认 HTML 模板作为回退操作。它应该看起来像这样：
<?php
// Lots of code here
// Here I could echo something
// echo "Welcome world!";
// but I will not so no text would be returned but ...
// in this case I have this fallback function that will only be fired if
// no text has been outputted by any mean before
// fallback_template();
fallback_template() {
echo "<html><head><title>Empty</title></head><body>No content</body></html>";
}我尝试使用headers_sent()进行检查，但它不起作用。有什么方法可以实现它，还是超出了PHP的可能性？我需要它进行浏览器同步，因此它始终保持活动状态。
<?php
ob_start();
// Lots of code here
// Here I could echo something
// echo "Welcome world!";
// but I will not so no text would be returned but ...
// in this case I have this fallback function that will only be fired if
// no text has been outputted by any mean before
// fallback_template();
fallback_template() {
// buffer is empty nothing was sent to client (using print, echo or an error happened)
if(ob_get_length() == 0 ) {
echo "<html><head><title>Empty</title></head><body>No content</body></html>";
}
}