如何导入/上传XLSX文件到数据库

我使用PHPExcel导入XLSX文件到我的相关数据库。但是在运行函数时，我得到了错误。我的代码如下所示:

:

public function readExcel()
    {
      //load library phpExcel
      $this->load->library("PHPExcel");
      //here i used microsoft excel 2007
      $objReader = PHPExcel_IOFactory::createReader('Excel2007');
      //set to read only
      $objReader->setReadDataOnly(true);
      //load excel file
      $objPHPExcel = $objReader->load("a.xls");
      $objWorksheet = $objPHPExcel->setActiveSheetIndex(0);
      //load model
      $this->load->model("User_model");
      //loop from first data until last data
      for($i=2; $i<=77; $i++)
      {
        $name = $objWorksheet->getCellByColumnAndRow(0,$i)->getValue();
        $address = $objWorksheet->getCellByColumnAndRow(1,$i)->getValue();
        $data_user = array(
        "name" => $name,
        "username" => $address );
        $this->User_model->add_data($data_user);
      }
}

:

function add_data($datauser)
{
  $this->db->insert('data',$datauser);
  return $this->db->insert_id();
} 

error::

致命错误:未捕获的异常'PHPExcel_Reader_Exception'与消息'Could not open .xlsx for reading!文件不存在。C:'xampp'htdocs'htdocs' school_erp'school' application'libraries'PHPExcel'Reader'Excel2007.php:343 Stack trace: #0 C:'xampp'htdocs'htdocs' school_erp'school'school'application'controllers' Trial_c .php(32): PHPExcel_Reader_Excel2007->load(' .xls') #1[内部函数]:Trial_c->readExcel() #2 C:'xampp'htdocs'htdocs' school_erp'school'school'system'core'CodeIgniter.php(359):call_user_func_array(Array, Array) #3 C:'xampp'htdocs'htdocs' school_erp'school'school'index.php(202): require_once('C:'xampp'htdocs 'htdocs'htdocs'school_erp'school'school'application'libraries'PHPExcel'Reader'Excel2007.php在line 343