09c06-1.php

来自「介绍PHP5的给类型函数应用」· PHP 代码 · 共 52 行

<?php
// A function to call that will set up & handle the output caching:
// The one optional parameter is to specify how many seconds must pass
//  before the page is recreated (defaults to 1 hour)
function cache_page($refresh = 3600) {
    // First of all generate the filename for this cache file. Base it upon
    //  the filename plus GET and POST variables, and use sha1() to hash it
    //  to a 40 character string so we don't run over filename length limits:
    $hash = sha1($_SERVER['PHP_SELF'] . '|G|' . serialize($_GET) .
        '|P|' . serialize($_POST));
    
    // Create the actual filename of where to find this.  It will be in a 
    //  subdirectory called 'cache' below the location of this library.
    $file = dirname(__FILE__) . '/cache/' . $hash;

    // Now that we've done all that, see if the last modified time is
    // less than the current time plus the refresh time
    if ((time() - @filemtime($file)) < $refresh) {
        // We are done, just return the file and exit
        readfile($file);
        exit();
    } else {
        // Otherwise, we have to actually create the page and save it.
        // To do this, first stop the user from aborting at this point so
        // it will definately complete.
        ignore_user_abort();
        
        // Now set up a shutdown function, so that we can ensure we actually
        // finish up properly when the script exits (for any reason)
        register_shutdown_function('_cache_page_exit', $file);
        
        // Now, to finish, we need to start output buffering
        ob_start();
    }
}

// Create the shutdown function that will be called for us when the script
// exits, allowing us to clean up everything.
function _cache_page_exit($file) {
    // We were buffering and are done.  First step is to get the contents
    //  and display it to the user.
    $output = ob_get_flush();

    // Flush all buffers so the user can get the data while we finish up.
    flush();
    
    // Save this data into the cache file, blowing away current contents
    // if they existed.  Request an exclusive lock for the writing just
    // so that two copies of this don't interfere with each other.
    file_put_contents($file, $output, LOCK_EX);
}
?>