使用PhpSpreadsheet导入和导出Excel

#### 安装

```
composer require phpoffice/phpspreadsheet
```

#### 导入

```
<?php

require './vendor/autoload.php';

use PhpOfficePhpSpreadsheetIOFactory;

$filename = './test.xlsx';

$reader = IOFactory::createReader('Xlsx');

$spreadsheet = $reader->load($filename);

$sheet = $spreadsheet->getActiveSheet();

$highestRow = $sheet->getHighestRow();

$highestColumn = $sheet->getHighestColumn();

$highestColumnIndex = PhpOfficePhpSpreadsheetCellCoordinate::columnIndexFromString($highestColumn);

for ($row = 1; $row <= $highestRow; $row++) {
    for ($col = 1; $col <= $highestColumnIndex; $col++) {
        echo $sheet->getCellByColumnAndRow($col, $row)->getValue(), "t";
    }
    echo "n";
}
```

#### 导出

```
<?php

require './vendor/autoload.php';

use PhpOfficePhpSpreadsheetIOFactory;
use PhpOfficePhpSpreadsheetSpreadsheet;

// 创建一个Excel对象
$spreadsheet = new Spreadsheet();

// 设置当前的活动sheet
$spreadsheet->setActiveSheetIndex(0);

// 获取当前活动sheet
$sheet = $spreadsheet->getActiveSheet();

// 设置sheet标题
$sheet->setTitle('data');

// 设置第一行数据
$sheet->setCellValue('A1', '标题')
      ->setCellValue('B1', '日期')
      ->setCellValue('C1', '状态');

// 设置第二行数据
$sheet->setCellValue('A2', '测试')
      ->setCellValue('B2', date('Y-m-d'))
      ->setCellValue('C2', '完成');

// 写入到文件
$writer = IOFactory::createWriter($spreadsheet, 'Xlsx');

$writer->save('./test.xlsx');
```