$objPHPExcel->setActiveSheetIndex(0)
->setCellValue('A1', 'Hello')
->setCellValue('B2', 'world!')
->setCellValue('C1', 'Hello')
->setCellValue('D2', 'world!');
像这样的格式可以写成：
$objPHPExcel->setActiveSheetIndex(0);
$objPHPExcel->setCellValue('A1', 'Hello');
$objPHPExcel->setCellValue('B2', 'world!');
$objPHPExcel->setCellValue('C1', 'Hello');
$objPHPExcel->setCellValue('D2', 'world!');