数字来自excel本身，日期以数值形式存储在excel中。http://www.cpearson.com/excel/datetime.htm
对于Laravel framework 5.6和maatwebsite/excel包3.1版，要将日期从excel数字转换为正常的日期格式，可以使用函数PhpOffice\PhpSpreadsheet\Shared\Date::excelToDateTimeObject($dateFromExcel)，它接受整数（excel日期）并返回DateTime对象。
更多信息请访问https://github.com/Maatwebsite/Laravel-Excel/issues/1832
从这个答案：https://stackoverflow.com/a/55139981/9133724

解决了！这是我用来解决我的问题的代码：

Carbon\Carbon::instance(\PhpOffice\PhpSpreadsheet\Shared\Date::excelToDateTimeObject($value));

我尝试了上述解决方案，但总是遇到非数值错误
我设法用
第一个月
\PhpOffice\PhpSpreadsheet\Shared\Date::excelToDateTimeObject($date)->format('d/m/Y')

基于Skyrem Brilliant的@skyrem-brilliant答案，我是这样解决的：

<?php

//...

class YourExcelImport implements OnEachRow, WithValidation, WithHeadingRow
{
   // ...

    /**
     * Tweak the data slightly before sending it to the validator
     * @param $data
     * @param $index
     * @return mixed
     */
    public function prepareForValidation($data, $index)
    {
        //Fix that Excel's numeric date (counting in days since 1900-01-01)
        $data['your_date_column'] = \PhpOffice\PhpSpreadsheet\Shared\Date::excelToDateTimeObject($data['your_date_column'])->format('Y-m-d');
        //...
    }

    /**
     * List the validation rules
     * @return array
     */
    public function rules(): array
    {
        return [
            'your_date_column'=>'required|date_format:Y-m-d',
            //..
        ];
    }
}
?>

这就完成了任务，验证通过。

这个"未知数字"是一个excel时间戳，这样它就可以在内部存储日期和时间数据。
例如：

123213.0: it's just a date
213233.1233: is a date and time
0.1233: it's one hour

如果可以Map单元格，并且知道哪一列将始终具有日期/时间/日期-时间，则可以使用Map的单元格或手动转换它，请参见：https://stackoverflow.com/a/59049044
否则，如果您的需要涉及动态解析日期时间字段，我已经编写了一个方法，负责自动动态检测值是否为日期时间（不管您是否知道该列中是否有日期时间），或者我尝试了各种数据类型，它工作正常

/**
 * @param Cell $cell
 * @param $value
 * 
 * @return boolean;
 */
public function bindValue(Cell $cell, $value)
{
    $formatedCellValue = $this->formatDateTimeCell($value, $datetime_output_format = "d-m-Y H:i:s", $date_output_format = "d-m-Y", $time_output_format = "H:i:s" );
    if($formatedCellValue != false){
        $cell->setValueExplicit($formatedCellValue, DataType::TYPE_STRING);
        return true;
    }

    // else return default behavior
    return parent::bindValue($cell, $value);
}

/**
 * 
 * Convert excel-timestamp to Php-timestamp and again to excel-timestamp to compare both compare
 * By Leonardo J. Jauregui ( @Nanod10 | siskit dot com )
 * 
 * @param $value (cell value)
 * @param String $datetime_output_format
 * @param String $date_output_format
 * @param String $time_output_format
 * 
 * @return $formatedCellValue
 */
private function formatDateTimeCell( $value, $datetime_output_format = "Y-m-d H:i:s", $date_output_format = "Y-m-d", $time_output_format = "H:i:s" )
{

    // is only time flag
    $is_only_time = false;
    
    // Divide Excel-timestamp to know if is Only Date, Only Time or both of them
    $excel_datetime_exploded = explode(".", $value);

    // if has dot, maybe date has time or is only time
    if(strstr($value,".")){
        // Excel-timestamp to Php-DateTimeObject
        $dateTimeObject = \PhpOffice\PhpSpreadsheet\Shared\Date::excelToDateTimeObject($value);
        // if Excel-timestamp > 0 then has Date and Time 
        if(intval($excel_datetime_exploded[0]) > 0){
            // Date and Time
            $output_format = $datetime_output_format;
            $is_only_time = false;
        }else{
            // Only time
            $output_format = $time_output_format;
            $is_only_time = true;
        }
    }else{
        // Only Date
        // Excel-timestamp to Php-DateTimeObject
        $dateTimeObject = \PhpOffice\PhpSpreadsheet\Shared\Date::excelToDateTimeObject($value);
        $output_format = $date_output_format;
        $is_only_time = false;
    }
        
    // Php-DateTimeObject to Php-timestamp
    $phpTimestamp = $dateTimeObject->getTimestamp();

    // Php-timestamp to Excel-timestamp
    $excelTimestamp = \PhpOffice\PhpSpreadsheet\Shared\Date::PHPToExcel( $phpTimestamp );
        
    // if is only Time
    if($is_only_time){
        // 01-01-1970 = 25569
        // Substract to match PhpToExcel conversion
        $excelTimestamp = $excelTimestamp - 25569;
    }

    /* 
    // uncoment to debug manualy and see if working
    $debug_arr = [
            "value"=>$value,
            "value_float"=>floatval($value),
            "dateTimeObject"=>$dateTimeObject,
            "phpTimestamp"=>$phpTimestamp,
            "excelTimestamp"=>$excelTimestamp,
            "default_date_format"=>$dateTimeObject->format('Y-m-d H:i:s'),
            "custom_date_format"=>$dateTimeObject->format($output_format)
        ];
        
    if($cell->getColumn()=="Q"){
        if($cell->getRow()=="2"){
            if(floatval($value)===$excelTimestamp){
                dd($debug_arr);
            }
        }
    }

    */
    
    // if the values match
    if( floatval($value) === $excelTimestamp ){
        // is a fucking date! ;)
        $formatedCellValue = $dateTimeObject->format($output_format);
        return $formatedCellValue;
    }else{
        // return normal value
        return false;
    }
    
}

只需使用此功能即可存储日期。

use PhpOffice\PhpSpreadsheet\Shared;

public function collection(Collection $collection)
{
    $errors = $this->validateBulk($collection);
    if (!empty($errors)) {
        return;
    }

    $holidays = [];
    foreach ($collection as $col) {
        Validator::make($col->toArray(), $this->rules())->validate();
        $holidays[] = [
            'title' => $col['title'],
            'holiday_date' => Date::excelToDateTimeObject($col['holiday_date'])
                ->format('y-m-d'),
            'holiday_year' => Date::excelToDateTimeObject($col['holiday_date'])
                ->format('y'),
        ];
        $this->rows++;
    }
    
    Holidays::insert($holidays);
}

在这种情况下，你可以参考我的代码。它工作得很好。

〈？php

namespace App\Imports;

use App\Models\Sale;
use Illuminate\Support\Facades\DB;
// use Maatwebsite\Excel\Concerns\WithHeadingRow;
use Maatwebsite\Excel\Concerns\ToModel;

class SalesImport implements ToModel
{
    /**
    * @param array $row
    *
    * @return \Illuminate\Database\Eloquent\Model|null
    */
    public function model(array $row)
    {
        return new Sale([
            "name" => $row[0],
            "birthday" => \PhpOffice\PhpSpreadsheet\Shared\Date::excelToDateTimeObject($row[1]),
            "gender" => $row[2],
            "age" => $row[3],
            "card_type" => $row[4],
            "identify_no" => $row[5],
            "address" => $row[6],
            "phone" => $row[7],
            "email" => $row[8],
        ]);
    }
}

我已经创建了一个函数来检查文件扩展名。它根据文件扩展名解析日期
1.控制器代码

public function store(FileImportRequest $request)
   {
       try {
         Excel::import(new FileImport($request->file->extension()), $request->file);
         }catch (\Error $ex) {
                     throw new \Exception('Error:' . $ex->getMessage());
                 }
         }

1.在FileImportRequest类中。

public function rules()
             {
                 return [
                     'file' => 'required|file|mimes:csv,xlsx,xsl'
                 ];
               }

1.在FileImport类中。

protected  $extension;

     public function __construct($extension)
     {
         $this->extension = $extension;
     }   

     public function model(array $row)
     {
         return new FileImport([
             'expires_at' => $this->checkExtension($row[8]),
             'created_at' => $this->checkExtension($row[9]),
         ]);
     }

 private function  checkExtension($dateTime)
   {
       switch ($this->extension) {
           case 'csv':
               return Carbon::parse($dateTime)->toDateTimeString();
               break;
           case 'xlsx':
           case 'xsl':
               return \PhpOffice\PhpSpreadsheet\Shared\Date::excelToDateTimeObject($dateTime);
               break;
       }
    }