PHP如何导出Excel

<?php
error_reporting(E_ALL);
date_default_timezone_set('Asia/Shanghai');
require_once './Classes/PHPExcel.php';
$data=array(
  0=>array(
    'id'=>1001,

    'username'=>'张飞',
    'password'=>'123456',
    'address'=>'三国时高老庄250巷101室'
  ),
  1=>array(
    'id'=>1002,
    'username'=>'关羽',
    'password'=>'123456',
    'address'=>'三国时花果山'
  ),
  2=>array(
    'id'=>1003,
    'username'=>'曹操',
    'password'=>'123456',
    'address'=>'延安西路2055弄3号'
  ),
  3=>array(
    'id'=>1004,
    'username'=>'刘备',
    'password'=>'654321',
    'address'=>'愚园路188号3309室'
  )
);
$objPHPExcel=new PHPExcel();
$objPHPExcel->getProperties()->setCreator('http://www.jb51.net')
               ->setLastModifiedBy('http://www.jb51.net')
               ->setTitle('Office 2007 XLSX Document')
               ->setSubject('Office 2007 XLSX Document')
               ->setDescription('Document for Office 2007 XLSX, generated using PHP classes.')
               ->setKeywords('office 2007 openxml php')

               ->setCategory('Result file');

$objPHPExcel->setActiveSheetIndex(0)

      ->setCellValue('A1','ID')

      ->setCellValue('B1','用户名')

      ->setCellValue('C1','密码')

      ->setCellValue('D1','地址');

$i=2;     

foreach($data as $k=>$v){

  $objPHPExcel->setActiveSheetIndex(0)
      ->setCellValue('A'.$i,$v['id'])
      ->setCellValue('B'.$i,$v['username'])
      ->setCellValue('C'.$i,$v['password'])
      ->setCellValue('D'.$i,$v['address']);

  $i++;

}
$objPHPExcel->getActiveSheet()->setTitle('三年级2班');

$objPHPExcel->setActiveSheetIndex(0);
$filename=urlencode('学生信息统计表').'_'.date('Y-m-dHis');
 
//生成xlsx文件
/*
header('Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet');
header('Content-Disposition: attachment;filename="'.$filename.'.xlsx"');
header('Cache-Control: max-age=0');
$objWriter=PHPExcel_IOFactory::createWriter($objPHPExcel,'Excel2007');
*/

//生成xls文件
header('Content-Type: application/vnd.ms-excel');
header('Content-Disposition: attachment;filename="'.$filename.'.xls"');
header('Cache-Control: max-age=0');
$objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel5');
$objWriter->save('php://output');
exit;