转超级简单实用的PhpOffice\PhpSpreadsheet读取csv、xls、xlsx方法

<?php
use PhpOffice\PhpSpreadsheet\IOFactory as PHPExcel_IOFactory;
/**
 * 读取excel文件内容
 * @param string $filename  完整的文件路径
 * @return array 读取表格的结果数据
 */
function readExcelFile($filename)
{
    $fileParts = pathinfo($filename);
    $filetype = strtolower($fileParts['extension']);
    if (strtolower($filetype)=='xls') {
        $objReader = PHPExcel_IOFactory::createReader('Xls');
    } elseif (strtolower($filetype)=='xlsx') {
        $objReader = PHPExcel_IOFactory::createReader('Xlsx');
    } elseif (strtolower($filetype)=='csv') {
        $objReader = PHPExcel_IOFactory::createReader('Csv')
                        ->setDelimiter(',')
                        ->setInputEncoding('GBK') //处理csv读取中文异常问题
                        ->setEnclosure('"');
    }
    $objReader->setReadDataOnly(true);
    $objPHPExcel = $objReader->load($filename);
    $objWorksheet = $objPHPExcel->getActiveSheet();
    $highestRow = $objWorksheet->getHighestRow(); // 获取总行数
    $highestColumn = $objWorksheet->getHighestColumn();// 获取最大列号
    $excelResult = [];
    // 从第2行开始读取
    $startRow = 2;
    for ($j = $startRow; $j <= $highestRow; $j++) {
        // 从A列读取数据
        for ($k = 'A'; $k <= $highestColumn; $k++) {
            // 读取单元格
            $excelResult[$j][$k] = (string)$objWorksheet->getCell("$k$j")->getValue();
        }
    }
    return $excelResult;
}