【php设计模式】责任链模式

<?php
define("WARNING_LEVEL", 1);
define("DEBUG_LEVEL", 2);
define("ERROR_LEVEL", 3);

abstract class AbstractLog{
    protected $level;
    protected $nextlogger;

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

    public function setNextLogger($next_logger){
        $this->nextlogger = $next_logger;
    }

    public function logMessage($level,$message){
        if($this->level == $level){
            $this->write($message);
        }

        if($this->nextlogger){
            $this->nextlogger->logMessage($level,$message);
        }
    }

    abstract function write($message);
}

class DebuggLogger extends AbstractLog{
    public function write($message){
        echo "Debug info: {$message} \n";
    }
}

class WarningLogger extends AbstractLog{
    public function write($message){
        echo "Warning info: {$message} \n";
    }
}

class ErrorLogger extends AbstractLog{
    public function write($message){
        echo "Error info: {$message} \n";
    }
}

function getChainOfLoggers(){
    $warning = new WarningLogger(WARNING_LEVEL);
    $debugg = new DebuggLogger(DEBUG_LEVEL);
    $error = new ErrorLogger(ERROR_LEVEL);

    $warning->setNextLogger($debugg);
    $debugg->setNextLogger($error);

    return $warning;
}

$chain = getChainOfLoggers();

$chain->logMessage(WARNING_LEVEL,"这是一条警告");
$chain->logMessage(DEBUG_LEVEL,"这是一条Debug");
$chain->logMessage(ERROR_LEVEL,"这是一条致命错误");

Warning info: 这是一条警告
Debug info: 这是一条Debug
Error info: 这是一条致命错误