jucai/app/Validators/Rules/UsernameRule.php

<?php

namespace App\Validators\Rules;

use Illuminate\Contracts\Validation\Rule;

class UsernameRule implements Rule
{
    /**
     * Create a new rule instance.
     *
     * @return void
     */
    public function __construct()
    {
        //
    }

    /**
     * Determine if the validation rule passes.
     *
     * @param  string  $attribute
     * @param  mixed  $value
     * @return bool
     */
    public function passes($attribute, $value)
    {
        //用户名验证,字母开头,包含6位以上数字与字母
        if (preg_match("/^(?=[a-zA-Z])(?!\d+)[A-Za-z0-9_.]{6,20}$/", $value)) {
            return true;
        }
        return false;
    }

    /**
     * Get the validation error message.
     *
     * @return string
     */
    public function message()
    {
        return '字母开头,包含6位以上数字、字母及大小写';
    }
}