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 = 'localhost';
  private $port = '27017';
 
  private $db;
  public $dbname;
  private $table = NULL;
 
  /**
    * Initialize the class and get the instance object of mongo
    */
  public function __construct($host = NULL, $port = NULL, $dbname = NULL, $table = NULL)
  {
 
    if (NULL === $dbname) {
      $this->throwError('The set cannot be empty!  ');
    }
 
    //Judge whether the host and port are passed    if (NULL !== $host) {
      $this->host = $host;
    }
 
    if (NULL !== $port) {
      $this->port = $port;
    }
 
    $this->table = $table;
 
    $this->mongo = new MongoClient($this->host . ':' . $this->port);
    if ($this->getVersion() >= '0.9.0') {
      $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;
  }
 
  /**
    * Singleton mode
    * @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;
  //}
 
  /**
    * Insert a data
    * @param array $doc
    */
  public function insert($doc = array())
  {
    if (empty($doc)) {
      $this->throwError('The inserted data cannot be empty!  ');
    }
    //Save data information    try {
      if (!$this->db->insert($doc)) {
        throw new MongoException('Insert data failed');
      }
    } catch (MongoException $e) {
      $this->throwError($e->getMessage());
    }
  }
 
  /**
    * Insert multiple data information
    * @param array $doc
    */
  public function insertMulti($doc = array())
  {
    if (empty($doc)) {
      $this->throwError('The inserted data cannot be empty!  ');
    }
    //Insert data information    foreach ($doc as $key => $val) {
      //Judge whether $val is an array      if (is_array($val)) {
        $this->insert($val);
      }
    }
  }
 
  /**
    * Find a record
    * @return array|null
    */
  public function findOne($where = NULL)
  {
    if (NULL === $where) {
      try {
        if ($result = $this->db->findOne()) {
          return $result;
        } else {
          throw new MongoException('Failed to find data');
        }
      } catch (MongoException $e) {
        $this->throwError($e->getMessage());
      }
    } else {
      try {
        if ($result = $this->db->findOne($where)) {
          return $result;
        } else {
          throw new MongoException('Failed to find data');
        }
      } catch (MongoException $e) {
        $this->throwError($e->getMessage());
      }
    }
 
  }
 
  /**
    * todo with conditions and then do it
    * Find all documents
    * @return MongoCursor
    */
  public function find($where = NULL)
  {
    if (NULL === $where) {
 
      try {
        if ($result = $this->db->find()) {
 
        } else {
          throw new MongoException('Failed to find data');
        }
      } catch (MongoException $e) {
        $this->throwError($e->getMessage());
      }
    } else {
      try {
        if ($result = $this->db->find($where)) {
 
        } else {
          throw new MongoException('Failed to find data');
        }
      } catch (MongoException $e) {
        $this->throwError($e->getMessage());
      }
    }
 
    $arr = array();
    foreach ($result as $id => $val) {
      $arr[] = $val;
    }
 
    return $arr;
  }
 
  /**
    * Get the number of records
    * @return int
    */
  public function getCount()
  {
    try {
      if ($count = $this->db->count()) {
        return $count;
      } else {
        throw new MongoException('Failed to find total number');
      }
    } catch (MongoException $e) {
      $this->throwError($e->getMessage());
    }
  }
 
  /**
    * Get all databases
    * @return array
    */
  public function getDbs()
  {
    return $this->mongo->listDBs();
  }
 
  /**
    * Delete the database
    * @param null $dbname
    * @return mixed
    */
  public function dropDb($dbname = NULL)
  {
    if (NULL !== $dbname) {
      $retult = $this->mongo->dropDB($dbname);
      if ($retult['ok']) {
        return TRUE;
      } else {
        return FALSE;
      }
    }
    $this->throwError('Please enter the database name to be deleted');
  }
 
  /**
    * Forced to close the database link
    */
  public function closeDb()
  {
    $this->mongo->close(TRUE);
  }
 
  /**
    * Output error message
    * @param $errorInfo Error content
    */
  public function throwError($errorInfo='')
  {
    echo "<h3>Error: $errorInfo</h3>";
    die();
  }
 
}