source: trunk/www.guidonia.net/wp/wp-admin/import/opml.php@ 44

<?php
/**
 * Links Import Administration Panel.
 *
 * @copyright 2002 Mike Little <mike@zed1.com>
 * @author Mike Little <mike@zed1.com>
 * @package WordPress
 * @subpackage Administration
 */

/** Load WordPress Administration Bootstrap */
$parent_file = 'tools.php';
$submenu_file = 'import.php';
$title = __('Import Blogroll');

class OPML_Import {

        function dispatch() {
                global $wpdb, $user_ID;
$step = $_POST['step'];
if (!$step) $step = 0;
?>
<?php
switch ($step) {
        case 0: {
                include_once('admin-header.php');
                if ( !current_user_can('manage_links') )
                        wp_die(__('Cheatin&#8217; uh?'));

                $opmltype = 'blogrolling'; // default.
?>

<div class="wrap">
<?php screen_icon(); ?>
<h2><?php _e('Import your blogroll from another system') ?> </h2>
<form enctype="multipart/form-data" action="admin.php?import=opml" method="post" name="blogroll">
<?php wp_nonce_field('import-bookmarks') ?>

<p><?php _e('If a program or website you use allows you to export your links or subscriptions as OPML you may import them here.'); ?></p>
<div style="width: 70%; margin: auto; height: 8em;">
<input type="hidden" name="step" value="1" />
<input type="hidden" name="MAX_FILE_SIZE" value="30000" />
<div style="width: 48%;" class="alignleft">
<h3><label for="opml_url"><?php _e('Specify an OPML URL:'); ?></label></h3>
<input type="text" name="opml_url" id="opml_url" size="50" class="code" style="width: 90%;" value="http://" />
</div>

<div style="width: 48%;" class="alignleft">
<h3><label for="userfile"><?php _e('Or choose from your local disk:'); ?></label></h3>
<input id="userfile" name="userfile" type="file" size="30" />
</div>

</div>

<p style="clear: both; margin-top: 1em;"><label for="cat_id"><?php _e('Now select a category you want to put these links in.') ?></label><br />
<?php _e('Category:') ?> <select name="cat_id" id="cat_id">
<?php
$categories = get_terms('link_category', 'get=all');
foreach ($categories as $category) {
?>
<option value="<?php echo $category->term_id; ?>"><?php echo esc_html(apply_filters('link_category', $category->name)); ?></option>
<?php
} // end foreach
?>
</select></p>

<p class="submit"><input type="submit" name="submit" value="<?php esc_attr_e('Import OPML File') ?>" /></p>
</form>

</div>
<?php
                break;
        } // end case 0

        case 1: {
                check_admin_referer('import-bookmarks');

                include_once('admin-header.php');
                if ( !current_user_can('manage_links') )
                        wp_die(__('Cheatin&#8217; uh?'));
?>
<div class="wrap">

<h2><?php _e('Importing...') ?></h2>
<?php
                $cat_id = abs( (int) $_POST['cat_id'] );
                if ( $cat_id < 1 )
                        $cat_id  = 1;

                $opml_url = $_POST['opml_url'];
                if ( isset($opml_url) && $opml_url != '' && $opml_url != 'http://' ) {
                        $blogrolling = true;
                } else { // try to get the upload file.
                        $overrides = array('test_form' => false, 'test_type' => false);
                        $_FILES['userfile']['name'] .= '.txt';
                        $file = wp_handle_upload($_FILES['userfile'], $overrides);

                        if ( isset($file['error']) )
                                wp_die($file['error']);

                        $url = $file['url'];
                        $opml_url = $file['file'];
                        $blogrolling = false;
                }

                global $opml, $updated_timestamp, $all_links, $map, $names, $urls, $targets, $descriptions, $feeds;
                if ( isset($opml_url) && $opml_url != '' ) {
                        if ( $blogrolling === true ) {
                                $opml = wp_remote_fopen($opml_url);
                        } else {
                                $opml = file_get_contents($opml_url);
                        }

                        /** Load OPML Parser */
                        include_once('link-parse-opml.php');

                        $link_count = count($names);
                        for ( $i = 0; $i < $link_count; $i++ ) {
                                if ('Last' == substr($titles[$i], 0, 4))
                                        $titles[$i] = '';
                                if ( 'http' == substr($titles[$i], 0, 4) )
                                        $titles[$i] = '';
                                $link = array( 'link_url' => $urls[$i], 'link_name' => $wpdb->escape($names[$i]), 'link_category' => array($cat_id), 'link_description' => $wpdb->escape($descriptions[$i]), 'link_owner' => $user_ID, 'link_rss' => $feeds[$i]);
                                wp_insert_link($link);
                                echo sprintf('<p>'.__('Inserted <strong>%s</strong>').'</p>', $names[$i]);
                        }
?>

<p><?php printf(__('Inserted %1$d links into category %2$s. All done! Go <a href="%3$s">manage those links</a>.'), $link_count, $cat_id, 'link-manager.php') ?></p>

<?php
} // end if got url
else
{
        echo "<p>" . __("You need to supply your OPML url. Press back on your browser and try again") . "</p>\n";
} // end else

if ( ! $blogrolling )
        do_action( 'wp_delete_file', $opml_url);
        @unlink($opml_url);
?>
</div>
<?php
                break;
        } // end case 1
} // end switch
        }

        function OPML_Import() {}
}

$opml_importer = new OPML_Import();

register_importer('opml', __('Blogroll'), __('Import links in OPML format.'), array(&$opml_importer, 'dispatch'));

?>