怎样在wordpress后台显示日志 ID

<?php
/*
Plugin Name: 在后台显示日志 ID
Plugin URI: http://blog.wpjam.com/m/how-to-display-post-id-in-the-wordpress-admin/
Description: WordPress 技巧：如何在后台显示日志 ID
Version: 0.1
Author: Denis
Author URI: http://blog.wpjam.com/
*/
add_filter('manage_posts_columns', 'wpjam_id_manage_posts_columns');
add_filter('manage_pages_columns', 'wpjam_id_manage_posts_columns');
function wpjam_id_manage_posts_columns($columns){
    $columns['post_id'] = 'ID';
    return $columns;
}

add_action('manage_posts_custom_column','wpjam_id_manage_posts_custom_column',10,2);
add_action('manage_pages_custom_column','wpjam_id_manage_posts_custom_column',10,2);
function wpjam_id_manage_posts_custom_column($column_name,$id){
    if ($column_name == 'post_id') {
        echo $id;
    }
}