Mongodb operation class implemented by PHP

<?php
  
/**
 * Created by PhpStorm.
 * User: yangyulong
 * Date: 2015/5/26
 * Time: 13:45
 */
class Mongo_db
{
  private static $instanceof = NULL;
  public $mongo;
  private $host = &#39;localhost&#39;;
  private $port = &#39;27017&#39;;
  
  private $db;
  public $dbname;
  private $table = NULL;
  
  /**
   * 初始化类，得到mongo的实例对象
   */
  public function __construct($host = NULL, $port = NULL, $dbname = NULL, $table = NULL)
  {
  
    if (NULL === $dbname) {
      $this->throwError(&#39;集合不能为空！&#39;);
    }
  
    //判断是否传递了host和port
    if (NULL !== $host) {
      $this->host = $host;
    }
  
    if (NULL !== $port) {
      $this->port = $port;
    }
  
    $this->table = $table;
  
    $this->mongo = new MongoClient($this->host . &#39;:&#39; . $this->port);
    if ($this->getVersion() >= &#39;0.9.0&#39;) {
      $this->dbname = $this->mongo->selectDB($dbname);
      $this->db = $this->dbname->selectCollection($table);
    } else {
      $this->db = $this->mongo->$dbname->$table;
    }
  }
  
  public function getVersion()
  {
    return MongoClient::VERSION;
  }
  
  /**
   * 单例模式
   * @return Mongo|null
   */
  //public static function getInstance($host=null, $port=null, $dbname=null, $table=null){
  //
  //  if(!(self::$instanceof instanceof self)){
  //    self::$instanceof = new self($host, $port, $dbname, $table);
  //  }
  //
  //  return self::$instanceof;
  //}
  
  /**
   * 插入一条数据
   * @param array $doc
   */
  public function insert($doc = array())
  {
    if (empty($doc)) {
      $this->throwError(&#39;插入的数据不能为空！&#39;);
    }
    //保存数据信息
    try {
      if (!$this->db->insert($doc)) {
        throw new MongoException(&#39;插入数据失败&#39;);
      }
    } catch (MongoException $e) {
      $this->throwError($e->getMessage());
    }
  }
  
  /**
   * 插入多条数据信息
   * @param array $doc
   */
  public function insertMulti($doc = array())
  {
    if (empty($doc)) {
      $this->throwError(&#39;插入的数据不能为空！&#39;);
    }
    //插入数据信息
    foreach ($doc as $key => $val) {
      //判断$val是不是数组
      if (is_array($val)) {
        $this->insert($val);
      }
    }
  }
  
  /**
   * 查找一条记录
   * @return array|null
   */
  public function findOne($where = NULL)
  {
    if (NULL === $where) {
      try {
        if ($result = $this->db->findOne()) {
          return $result;
        } else {
          throw new MongoException(&#39;查找数据失败&#39;);
        }
      } catch (MongoException $e) {
        $this->throwError($e->getMessage());
      }
    } else {
      try {
        if ($result = $this->db->findOne($where)) {
          return $result;
        } else {
          throw new MongoException(&#39;查找数据失败&#39;);
        }
      } catch (MongoException $e) {
        $this->throwError($e->getMessage());
      }
    }
  
  }
  
  /**
   * todo 带条件的随后做
   * 查找所有的文档
   * @return MongoCursor
   */
  public function find($where = NULL)
  {
    if (NULL === $where) {
  
      try {
        if ($result = $this->db->find()) {
  
        } else {
          throw new MongoException(&#39;查找数据失败&#39;);
        }
      } catch (MongoException $e) {
        $this->throwError($e->getMessage());
      }
    } else {
      try {
        if ($result = $this->db->find($where)) {
  
        } else {
          throw new MongoException(&#39;查找数据失败&#39;);
        }
      } catch (MongoException $e) {
        $this->throwError($e->getMessage());
      }
    }
  
    $arr = array();
    foreach ($result as $id => $val) {
      $arr[] = $val;
    }
  
    return $arr;
  }
  
  /**
   * 获取记录条数
   * @return int
   */
  public function getCount()
  {
    try {
      if ($count = $this->db->count()) {
        return $count;
      } else {
        throw new MongoException(&#39;查找总数失败&#39;);
      }
    } catch (MongoException $e) {
      $this->throwError($e->getMessage());
    }
  }
  
  /**
   * 获取所有的数据库
   * @return array
   */
  public function getDbs()
  {
    return $this->mongo->listDBs();
  }
  
  /**
   * 删除数据库
   * @param null $dbname
   * @return mixed
   */
  public function dropDb($dbname = NULL)
  {
    if (NULL !== $dbname) {
      $retult = $this->mongo->dropDB($dbname);
      if ($retult[&#39;ok&#39;]) {
        return TRUE;
      } else {
        return FALSE;
      }
    }
    $this->throwError(&#39;请输入要删除的数据库名称&#39;);
  }
  
  /**
   * 强制关闭数据库的链接
   */
  public function closeDb()
  {
    $this->mongo->close(TRUE);
  }
  
  /**
   * 输出错误信息
   * @param $errorInfo 错误内容
   */
  public function throwError($errorInfo=&#39;&#39;)
  {
    echo "<h3>出错了：$errorInfo</h3>";
    die();
  }
  
}