guagua_php/app/model/ZoneAmountParam.php

<?php

namespace app\model;

use \think\Model;

class ZoneAmountParam extends Model
{

    /**
     * 获取随机金额
     * @param $data
     * @return array
     * @throws \think\db\exception\DataNotFoundException
     * @throws \think\db\exception\DbException
     * @throws \think\db\exception\ModelNotFoundException
     */
    public static function getRandAmount($data = [])
    {
        if (empty($data)) {
            $model = new ZoneAmountParam();
            $data = $model->select()->toArray();
        }

        $totalWeight = 0;
        foreach ($data as $pattern) {
            $totalWeight += $pattern['weight'];
        }

        // 随机金额
        $amount = '0.00';

        // 生成随机数
        $randomNumber = rand(1, $totalWeight);

        foreach ($data as $pattern) {
            $randomNumber -= $pattern['weight'];
            if ($randomNumber <= 0) {
                $amount = $pattern['amount'];
                break;
            }
        }

        return [
            'data' => $data,
            'amount' => $amount
        ];
    }

}