PHP is not limited to outputting html. PHP can output images, pdf, javascript files, etc. Browsers determine what type of content is by analyzing the headers sent. In this tutorial I will present you with some examples of how to send headers. To send PHP header use the function header(). You must call this function before any output. Use the function headers_sent() to check whether the headers have been sent and output started.
301 moved permanently (redirect):
<?php header('HTTP/1.1 301 Moved Permanently'); header('Location: http://www.example.com'); die(); ?>
302 moved temporarily(redirect):
<?php header('Location: http://www.example.com'); die(); ?>
404 Page Not Found:
<?php header('HTTP/1.1 404 Not Found'); ?>
Service not avaliable:
<?php header('HTTP/1.1 503 Service Temporarily Unavailable'); header('Status: 503 Service Temporarily Unavailable'); header('Retry-After: 60'); ?>
CSS:
<?php header('Content-Type: text/css'); ?>
Javascript header:
<?php header('Content-Type: application/javascript'); ?>
Images:
For JPEG(jpg): <?php header('Content-Type: image/jpeg'); ?>
For PNG:
<?php header('Content-Type: image/png'); ?>
For BMP:
<?php header('Content-Type: image/bmp'); ?>
PDF (output pdf with php):
<?php header('Content-Type: application/pdf'); echo file_get_contents('filename.pdf'); ?>
Cache (force browsers not to cache files):
<?php header('Expires: Sat, 26 Jul 1997 05:00:00 GMT'); header('Cache-Control: no-store, no-cache, must-revalidate'); header('Cache-Control: pre-check=0, post-check=0, max-age=0'); header ('Pragma: no-cache'); ?>
Download dialog:
<?php header('Content-Disposition: attachment; filename=' . urlencode($f)); header('Content-Type: application/force-download'); header('Content-Type: application/octet-stream'); header('Content-Type: application/download'); header('Content-Description: File Transfer'); header('Content-Length: ' . filesize($f)); echo file_get_contents($f); ?>
Authentication (force the browser to pop up a Username/Password input window) – only available when PHP is running as an Apache module:
<?php if (!isset($_SERVER['PHP_AUTH_USER'])) { header('WWW-Authenticate: Basic realm="The Realm"'); header('HTTP/1.0 401 Unauthorized'); echo 'If cancel is pressed this text shows'; die(); } else { //always escape your data// $user='user'; $pass='pass'; if($_SERVER['PHP_AUTH_USER']==$user && $_SERVER['PHP_AUTH_PW']==$pass){ echo 'Authorized'; } } ?>
引自:PHPWeby http://phpweby.com/tutorials/php/35