Sharing of instance operations of mongoDB singleton mode implemented in PHP

class Mongo_db
{
  private static $cli;
  /**
   * 不允许初始化
   */
  private function __construct()
  {
    $config = Config::get('config.mongo_config');
    if(empty($config)){
      $this->throwError('无法连接数据库！');
    }
    if (!empty($config["user_name"])) {
      $this->mongo = new MongoClient("mongodb://{$config['user_name']}:{$config['password']}@{$config['host']}:{$config['port']}");
    }else {
      $this->mongo = new MongoClient($config['host'] . ':' . $config['port']);
    }
  }
  /**
  * 单例模式
  * @return Mongo|null
  */
 public static function cli(){
  if(!(self::$cli instanceof self)){
   self::$cli = new self();
  }
  return self::$cli->mongo;
 }
}
$mongo = Mongo_db::cli()->test->mycollection; // test 是选择的数据库 ， mycollection 是选择的表。 因为使用单例模式，所以，只会实例一个资源具体操作再参考下面的文章吧