wordpress 自动获取文章第一张图片做为特色图片

如标题所示这期带来的是特色图片自动生成代码
该代码能获取文章的第一张图片然后将此图片存放到本地空间并设置为特色图片
相比其他只能获取本站图片的生成代码这代码确实是非常强大

 <?php
add_action('publish_post', 'ipc_publish_post');
/**
 * Function to save first image in post as post thumbmail.
 */
function ipc_publish_post($post_id)
{
    global $wpdb;
    // First check whether Post Thumbnail is already set for this post.
    if (get_post_meta($post_id, '_thumbnail_id', true) || get_post_meta($post_id, 'skip_post_thumb', true)) {
        return;
    }
    $post = $wpdb->get_results("SELECT * FROM {$wpdb->posts} WHERE id = {$post_id}");
    // Initialize variable used to store list of matched images as per provided regular expression
    $matches = array();
    // Get all images from post's body
    preg_match_all('/<\\s*img [^\\>]*src\\s*=\\s*[\\""\']?([^\\""\'>]*)/i', $post[0]->post_content, $matches);
    if (count($matches)) {
        foreach ($matches[0] as $key => $image) {
            /**
             * If the image is from wordpress's own media gallery, then it appends the thumbmail id to a css class.
             * Look for this id in the IMG tag.
             */
            preg_match('/wp-image-([\\d]*)/i', $image, $thumb_id);
            $thumb_id = $thumb_id[1];
            // If thumb id is not found, try to look for the image in DB. Thanks to "Erwin Vrolijk" for providing this code.
            if (!$thumb_id) {
                $image = substr($image, strpos($image, '"') + 1);
                $result = $wpdb->get_results(("SELECT ID FROM {$wpdb->posts} WHERE guid = '" . $image) . '\'');
                $thumb_id = $result[0]->ID;
            }
            // Ok. Still no id found. Some other way used to insert the image in post. Now we must fetch the image from URL and do the needful.
            if (!$thumb_id) {
                $thumb_id = ipc_generate_post_thumb($matches, $key, $post[0]->post_content, $post_id);
            }
            // If we succeed in generating thumg, let's update post meta
            if ($thumb_id) {
                update_post_meta($post_id, '_thumbnail_id', $thumb_id);
                break;
            }
        }
    }
}
// end ipc_publish_post()
/**
 * Function to fetch the image from URL and generate the required thumbnails
 */
function ipc_generate_post_thumb($matches, $key, $post_content, $post_id)
{
    // Make sure to assign correct title to the image. Extract it from img tag
    $imageTitle = '';
    preg_match_all('/<\\s*img [^\\>]*title\\s*=\\s*[\\""\']?([^\\""\'>]*)/i', $post_content, $matchesTitle);
    if (count($matchesTitle) && isset($matchesTitle[1])) {
        $imageTitle = $matchesTitle[1][$key];
    }
    // Get the URL now for further processing
    $imageUrl = $matches[1][$key];
    // Get the file name
    $filename = substr($imageUrl, strrpos($imageUrl, '/') + 1);
    if (!(($uploads = gogo_upload_dir(current_time('mysql'))) && false === $uploads['error'])) {
        return null;
    }
    // Generate unique file name
    $filename = gogo_unique_filename($uploads['path'], $filename);
    // Move the file to the uploads dir
    $new_file = $uploads['path'] . "/{$filename}";
    if (!ini_get('allow_url_fopen')) {
        $file_data = curl_get_file_contents($imageUrl);
    } else {
        $file_data = @file_get_contents($imageUrl);
    }
    if (!$file_data) {
        return null;
    }
    file_put_contents($new_file, $file_data);
    // Set correct file permissions
    $stat = stat(dirname($new_file));
    $perms = $stat['mode'] & 438;
    @chmod($new_file, $perms);
    // Get the file type. Must to use it as a post thumbnail.
    $gogo_filetype = gogo_check_filetype($filename, $mimes);
    extract($gogo_filetype);
    // No file type! No point to proceed further
    if ((!$type || !$ext) && !current_user_can('unfiltered_upload')) {
        return null;
    }
    // Compute the URL
    $url = $uploads['url'] . "/{$filename}";
    // Construct the attachment array
    $attachment = array('post_mime_type' => $type, 'guid' => $url, 'post_parent' => null, 'post_title' => $imageTitle, 'post_content' => '');
    $thumb_id = gogo_insert_attachment($attachment, $file, $post_id);
    if (!is_gogo_error($thumb_id)) {
        require_once ABSPATH . '/wp-admin/includes/image.php';
        // Added fix by misthero as suggested
        gogo_update_attachment_metadata($thumb_id, gogo_generate_attachment_metadata($thumb_id, $new_file));
        update_attached_file($thumb_id, $new_file);
        return $thumb_id;
    }
    return null;
}

加载到主题functions.php中
以后只要有写带图片的文章他会自动帮你生成特色图片

如图所示的就是该代码自动生成的