PHP 异常处理中如何实现错误码和错误消息的映射？

<?php

// 创建一个异常类
class MyException extends Exception
{
    protected $errorCode;

    // 构造函数：接受错误代码和消息
    public function __construct($errorCode, $message)
    {
        $this->errorCode = $errorCode;
        parent::__construct($message);
    }

    // 获取错误代码
    public function getErrorCode()
    {
        return $this->errorCode;
    }
}

// 错误代码和消息映射
$errorCodes = array(
    100 => "Invalid input",
    200 => "Database error",
    300 => "File not found"
);

// 创建并抛出异常
try {
    // 模拟出现错误
    throw new MyException(100, "The input is invalid.");
} catch (MyException $e) {
    // 获取错误代码和消息
    $errorCode = $e->getErrorCode();
    $errorMessage = $errorCodes[$errorCode];

    // 显示错误消息
    echo "Error: $errorMessage";
}

try {
    // 创建线索
    createLead(...);
} catch (MyException $e) {
    $errorCode = $e->getErrorCode();
    switch ($errorCode) {
        case 200:
            $errorMessage = "Failed to connect to the database.";
            break;
        default:
            $errorMessage = "An unknown error occurred.";
    }
    // 显示错误消息
    echo $errorMessage;
}