Community Learn Tools Library Leisure
search
English
Home > php教程 > php手册 > 七. PHP模式设计----执行及描述任务

七. PHP模式设计----执行及描述任务

WBOY
Release： 2016-06-13 09:20:38
Original
1356 people have browsed it

七. PHP模式设计----执行及描述任务

1. 解析器模式


//解析器内容类
//用于存放表达式的运算结果,并且能根据传入的表达式返回当初记录的结果
class InterpreterContext{
    private $expressionstore=array();
    //将对象放进array里面,索引号是对象ID号
    function replace(Expression $exp,$value){
        $this->expressionstore[$exp->getKey()]=$value;
    }
    function lookup(Expression $exp){
        return $this->expressionstore[$exp->getKey()];
    }
}
abstract class Expression{
    private static $keyCount=0;
    private $key;
    abstract function interpret(InterpreterContext $context);
    //每一个对象都有一个唯一的key
    function getKey(){
        if(!isset($this->key)){
            $this->key=++self::$keyCount;
        }
        return $this->key;
    }
}
//字符串
class LiteralExpression extends Expression{
    private $value;
    function __construct($value){
        $this->value=$value;
    }
    function interpret(InterpreterContext $context){
        $context->replace($this, $this->value);
    }
}
//变量
class VariableExpression extends Expression{
    private $value;
    private $name;
    function __construct($name,$value=null){
        $this->name=$name;
        $this->value=$value;
    }
    function setValue($value){
        $this->value=$value;
    }
    function getKey(){
        return $this->name;
    }
    function interpret(InterpreterContext $context){
        if(!is_null($this->value)){
            $context->replace($this, $this->value);
            //设置为空,可以避免在没有修改value的情况下再次调用该方法的时候,
            //也第二次调用了InterpreterContext::replece
            $this->value=null;
        }
    }
}
//操作符表达式 抽象基类
abstract class OperatorExpression extends Expression{
    //左右操作数
    protected $l_op;
    protected $r_op;
    function __construct(Expression $l_op,Expression $r_op){
        $this->l_op=$l_op;
        $this->r_op=$r_op;
    }
    function interpret(InterpreterContext $context){
        $this->l_op->interpret($context);
        $this->r_op->interpret($context);
        $result_l=$context->lookup($this->l_op);
        $result_r=$context->lookup($this->r_op);
        $this->doInterpret($context, $result_l, $result_r);
    }
    protected abstract function doInterpret(InterpreterContext $context,$result_l,$result_r);
}
//相等表达式
class EqualsExpression extends OperatorExpression{
    //计算后将结果保存进this里...
    protected function doInterpret(InterpreterContext $context,$result_l,$result_r){
        $context->replace($this, $result_l==$result_r);
    }
}
//布尔或表达式
class BooleanOrExpression extends OperatorExpression{
    protected function doInterpret(InterpreterContext $context, $result_l, $result_r){
        $context->replace($this, $result_l || $result_r);
    }
}
//布尔与表达式
class BooleanAndExpression extends OperatorExpression{
    protected function doInterpret(InterpreterContext $context, $result_l, $result_r){
        $context->replace($this, $result_l && $result_r);
    }
}
/*
$context=new InterpreterContext();
$literal=new LiteralExpression("Bob");
$literal->interpret($context);
print $context->lookup($literal);//Bob
$context=new InterpreterContext();
$myvar=new VariableExpression("V","one");
$myvar->interpret($context);
print $context->lookup($myvar);//one
$myothervar=new VariableExpression("V");
$myvar->interpret($context);
print $context->lookup($myvar);//one
*/
//利用上面的代码来检测迷你型语言
//$input equals "4" or $input equals "four"
$context=new InterpreterContext();
//一个没有赋值的变量
$input=new VariableExpression('input');
//定义一个复杂的布尔型变量,初始化的参数被保存在l_op,r_op里面
//注意,此时他们还没有进行相关运算,必须等到调用布尔型变量的interpret()
//之后,布尔型变量里面的参数才会各自调用自身的interpret,形成一个调用栈...
$statement=new BooleanOrExpression(
        new EqualsExpression($input, new LiteralExpression('four')), 
        new EqualsExpression($input, new LiteralExpression('4')));
$statement->interpret($context);
print $context->lookup($statement);
foreach (array('four','4','52') as $val){
    $input->setValue($val);
    print "$val:\n";
    $statement->interpret($context);
    if($context->lookup($statement)){
        print "top marks\n";
    }else{
        print "dunce hat on\n\n";
    }
}
/*four:
top marks
4:
top marks
52:
dunce hat on*/  

2.策略模式
      将类中许多不同操作而且是来自同一个接口的算法,独立起来封装在一个新类中,主类在由分类组合或者聚合而成

//Question类将由Marker聚合而成
abstract class Question{
    protected $prompt;
    protected $marker;
    function __construct($prompt,Marker $marker){
        $this->marker=$marker;
        $this->prompt=$prompt;
    }
    //利用委托实现
    function mark($response){
        return $this->marker->mark($response);
    }
}
class TextQuestion extends Question{
    //处理文本问题特有的操作
}
class AVQuestion extends Question{
    //处理语音问题特有操作
}
//策略对象
//将算法部分独立出来封装在Marker类中....
abstract class Marker{
    protected $test;
    function __construct($test){
        $this->test=$test;
    }
    abstract function mark($response);
}
//MarkLogic语言
class MarkLogicMarker extends Marker{
    protected $engine;
    function __construct($test){
        parent::__construct($test);
    }
    function mark($response){
        //模拟返回true
        return true;
    }
}
//直接匹配
class MatchMarker extends Marker{
    function mark($response){
        return ($this->test==$response);
    }
}
//正则表达式
class RegexpMarker extends Marker{
    function mark($response){
        return (preg_match($this->test, $response));
    }
}
//客户端示例代码
$markers=array(new RegexpMarker("/f.ve/"),
        new MatchMarker("fivev"),
        new MarkLogicMarker('$input equals "five"'));
foreach($markers as $marker){
    print get_class($marker)."\n";
    //新建一个问题,将marker实例传进去
    $question=new TextQuestion("How many beans make five", $marker);
    foreach (array("five","four") as $response){
        print "\t response:$response: ";
        if($question->mark($response)){
            print "well done\n";
        }else{
            print "never mind\n";
        }
    }
}
/*RegexpMarker
     response:five: well done
     response:four: never mind
MatchMarker
     response:five: never mind
     response:four: never mind
MarkLogicMarker
     response:five: well done
     response:four: well done
*/

3 观察者模式

     观察者模式的和兴是把客户元素(观察者)从一个中心类中分离开来.当主体中有事件发生时,观察者必须被通知到!同时观察者和主体类不是通过硬编码实现,而是通过接口组合聚合实现
*问题
// Login类(主体类)
class Login {
    const LOGIN_USER_UNKNOWN = 1;
    const LOGIN_WRONG_PASS = 2;
    const LOGIN_ACCESS = 3;
    private $status = array ();
    // 登录操
    function handleLogin($user, $pass, $ip) {
        $ret=false;
        switch (rand ( 1, 3 )) {
            case 1 :
                $this->setStatus ( self::LOGIN_ACCESS, $user, $ip );
                $ret=ture;
                break;
            case 2 :
                $this->setStatus ( self::LOGIN_WRONG_PASS, $user, $ip );
                $ret=false;
                break;
            case 3 :
                $this->setStatus ( self::LOGIN_USER_UNKNOWN, $user, $ip );
                $ret=false;
                break;
            default:
                $ret=false;
        }
        //如果需要记录IP时
        Logger::logIP($user, $ip, $this->getStatus());
        //如果需要把登录失败的人的IP发送到管理员邮箱时...
        if(!$ret){
            Notifier::mailWarning($user, $ip, $this->getStatus());
        }
        //还需要其他功能时,比如特殊IP需要设置cookie等...
        //需要在这里面一直添加...
        return $ret;
    }
    function setStatus($status, $user, $ip) {
        $this->status = array ($status,$user,$ip);
    }
    function getStatus(){
        return $this->status;
    }
}
class Logger{
    static function logIP($user,$ip,$status){}
}
class Notifier{
    static function mailWarning($user,$ip,$status){}
}
*利用观察者模式,使代码改动少些....
// 主体类的抽象接口
interface Observable{
    //附加
    function attach(Observer $observer);
    //删除
    function detach(Observer $observer);
    //通知
    function notify();
}
// Login类(主体类)
class Login implements Observable{
    const LOGIN_USER_UNKNOWN = 1;
    const LOGIN_WRONG_PASS = 2;
    const LOGIN_ACCESS = 3;
    private $observers;
    private $status = array ();
    // 登录操作
    function handleLogin($user, $pass, $ip) {
        $ret=false;
        switch (rand ( 1, 3 )) {
            case 1 :
                $this->setStatus ( self::LOGIN_ACCESS, $user, $ip );
                $ret=ture;
                break;
            case 2 :
                $this->setStatus ( self::LOGIN_WRONG_PASS, $user, $ip );
                $ret=false;
                break;
            case 3 :
                $this->setStatus ( self::LOGIN_USER_UNKNOWN, $user, $ip );
                $ret=false;
                break;
            default:
                $ret=false;
        }
        //使用观察者模式之后,如果需要增加新功能,只需要在本类中添加观察者实例即可...
        $this->notify();
        return $ret;
    }
    function setStatus($status, $user, $ip) {
        $this->status = array ($status,$user,$ip);
    }
    function getStatus(){
        return $this->status;
    }
    function attach(Observer $observer){
        $this->observers[]=$observer;
    }
    function detach(Observer $observer){
        $newObserver=array();
        foreach ($this->observers as $obs){
            if($obs!==$observer){
                $newObserver[]=$obs;
            }
        }
        $this->observers=$newObserver;
    }
    //通知所有观察者
    function notify(){
        foreach ($this->observers as $bos){
            $bos->update($this);
        }
    }
}
//观察者接口
interface Observer{
    function update(Observable $observable);
}
class SecurityMonitor implements Observer{
    function update(Observable $observable){
        //getStatus()不是Observable接口规定的方法
        $status=$observable->getStatus();
        //对status的判断也涉及到耦合问题
        if($status[0]==Login::LOGIN_WRONG_PASS){
            //发送邮件给管理员
            print __CLASS__.":\t sending mail to sysadmin\n";
        }
    }
}
$login=new Login();
$login->attach(new SecurityMonitor());
$login->handleLogin("coco", "123456", "127.0.0.1");//有可能输出发送消息到管理员

 *改进后的观察者模式

//可观察元素:主体类的基接口
interface Observable{
    //附加
    function attach(Observer $observer);
    //删除
    function detach(Observer $observer);
    //通知
    function notify();
}
// Login类(主体类)
class Login implements Observable{
    const LOGIN_USER_UNKNOWN = 1;
    const LOGIN_WRONG_PASS = 2;
    const LOGIN_ACCESS = 3;
    private $observers;
    private $status = array ();
    // 登录操作
    function handleLogin($user, $pass, $ip) {
        $ret=false;
        switch (rand ( 1, 3 )) {
            case 1 :
                $this->setStatus ( self::LOGIN_ACCESS, $user, $ip );
                $ret=ture;
                break;
            case 2 :
                $this->setStatus ( self::LOGIN_WRONG_PASS, $user, $ip );
                $ret=false;
                break;
            case 3 :
                $this->setStatus ( self::LOGIN_USER_UNKNOWN, $user, $ip );
                $ret=false;
                break;
            default:
                $ret=false;
        }
        //使用观察者模式之后,如果需要增加新功能,只需要在本类中添加观察者实例即可...
        $this->notify();
        return $ret;
    }
    function setStatus($status, $user, $ip) {
        $this->status = array ($status,$user,$ip);
    }
    function getStatus(){
        return $this->status;
    }
    function attach(Observer $observer){
        $this->observers[]=$observer;
    }
    function detach(Observer $observer){
        $newObserver=array();
        foreach ($this->observers as $obs){
            if($obs!==$observer){
                $newObserver[]=$obs;
            }
        }
        $this->observers=$newObserver;
    }
    //通知所有观察者
    function notify(){
        foreach ($this->observers as $bos){
            $bos->update($this);
        }
    }
}
//观察者接口
interface Observer{
    function update(Observable $observable);
}
//Login:观察者超类(用于解决直接在Observer中调用具体的Observable子类造成的风险)
abstract class LoginObserver implements Observer{
    private $login;
    function __construct(Login $login){
        $this->login=$login;
        $this->login->attach($this);
    }
    //该方法在Observable的子类某些方法被调用时触发
    function update(Observable $observable){
        //触发该方法时,传入的参数必须是Login才有效...
        if($this->login===$observable){
             $this->doUpdate($observable);
        }
    }
    abstract function doUpdate(Login $login);
    
}
//改进后的观察者能保证调用的Observable实例方法一定存在
class SecurityMonitor extends LoginObserver{
    function doUpdate(Login $login){
        $status=$login->getStatus();
        //对status的判断也涉及到耦合问题
        if($status[0]==Login::LOGIN_WRONG_PASS){
            //发送邮件给管理员
            print __CLASS__.":\t sending mail to sysadmin\n";
        }
    }
}
//日常记录
class GeneralLogger extends LoginObserver{
    function doUpdate(Login $login){
        $status=$login->getStatus();
        //添加记录到log中
        //...
        print __CLASS__."\t add login data to log\n";
    }
}
//合作伙伴工具类
class PartnershipTool extends LoginObserver{
    function doUpdate(Login $login){
        $status=$login->getStatus();
        //检查IP,如果匹配,则设置cookie...
        //...
        print __CLASS__."\t set cookie if IP matches a list\n";
    }
}
//客户端代码有一点点改变...
$login=new Login();
new SecurityMonitor($login);
new GeneralLogger($login);
new PartnershipTool($login);
$login->handleLogin("coco", "123456", "127.0.0.1");
/*
 * 有可能输出
 *SecurityMonitor:     sending mail to sysadmin
 *GeneralLogger     add login data to log
 *PartnershipTool    set cookie if IP matches a list
 **/

4. 访问者模式
       当使用对象集合时,我们可能需要对结构上每一个单独的组件应用各种操作.这样的操作可以内建于组件本身,毕竟组件内部调用其他组件是最方便的. 
       但是这种方法也存在问题,因为我们并不知道所有可能需要的执行的操作.如果每增加一个操作,就在类中增加一个对于新操作的支持,类就会变得越来越臃肿.访问者模式可以解决这个问题.

//本例是基于"文明"游戏的代码建立而成...
//*战斗单元类
abstract class Unit{
    //深度
    protected $depth=0;
    //攻击强度
    abstract function bombardStrength();
    function getComposite(){
        return null;
    }
    //为访问者模式打造的方法
    function accept(ArmyVisitor $visitor){
        //构建一个根据自己规则定义的方法名,然后交给visitor自身调用
        $method="visit".get_class($this);
        $visitor->$method($this);
    }
    //用于计算Unit在对象树中的深度
    protected function setDepth($depth){
        $this->depth==$depth;
    }
    function getDepth(){
        return $this->depth;
    }
}
//复合抽象类
abstract class CompositeUnit extends Unit{
    protected $units=array();
    //为访问者模式打造的方法
    function accept(ArmyVisitor $visitor){
        //构建一个根据自己规则定义的方法名,然后交给visitor自身调用
        //先调用父类accept(),再遍历调用子元素accept()
        parent::accept($visitor);
        foreach ($this->units as $thisunit){
            $thisunit->accept($visitor);
        }
    }
    //可以不用写bombardStrength()
    function getComposite(){
        return $this;
    }
    //添加单元
    //同时标记节点在对象树中的深度
    function addUnit(Unit $unit){
        if(!empty($unit)){
            if(in_array($unit, $this->units,true)){
                return;
            }
            //可以用下面代码替换in_array()函数
//             foreach ($this->units as $thisunit){
//                 if($thisunit===$unit){
//                     return;
//                 }
//             }
            //计算好深度先...
            $unit->setDepth($this->depth+1);
            array_push($this->units, $unit);
        }
    }
    function removeUnit(Unit $unit){
        $this->units=array_udiff($this->units, array($unit), function ($a,$b){return ($a===$b?0:1);});
    }
    
}
//射手
class Archer extends Unit{
    function bombardStrength(){
        return 4;
    }
}
//激光塔
class LaserCannonUnit extends Unit{
    function bombardStrength(){
        return 44;
    }
}
//军队:由战斗单元组成
class Army extends CompositeUnit{
    //计算总强度
    function bombardStrength(){
        $ret=0;
        foreach ($this->units as $unit){
            $ret+=$unit->bombardStrength();
        }
        return $ret;
    }
    //移动能力,防御能力...省略
}
//运兵船:一个类似军队的单元,它具备10个战斗单元,有攻击力
class TroopCarrier extends CompositeUnit{
    //具备和军队差不多的方法和属性
    function bombardStrength(){
        //Do something...
    }
}
//军队访问者基类
abstract class ArmyVisitor{
    //相关方法待会写...
    //Army可能有多少种Unit,这里就有多少个visit方法...
    //方法命名规则为visit+类名
    //默认的visit
    abstract function visit(Unit $unit);
    function visitArcher(Archer $node){
        $this->visit($node);
    }
    function visitLaserCannonUnit(LaserCannonUnit $node){
        $this->visit($node);
    }
    function visitArmy(Army $node){
        $this->visit($node);
    }
    function visitTroopCarrier(TroopCarrier $node){
        $this->visit($node);
    }
}
//具体的Army访问者类,用于转存文本
class TextDumpArmyVisitor extends ArmyVisitor{
    private $text="";
    function visit(Unit $node){
        $ret="";
        $pad=4*$node->getDepth();
        $ret.=sprintf("%{$pad}s","");
        $ret.=get_class($node).":";
        $ret.="bombard: ".$node->bombardStrength()."\n";
        $this->text.=$ret;
    }
    function getText(){
        return $this->text;
    }
}
//客户端实例代码
$army=new Army();
$army->addUnit(new Archer());
$army->addUnit(new LaserCannonUnit());
$textdump=new TextDumpArmyVisitor();
$army->accept($textdump);
print $textdump->getText();
/*  
 *  Army:bombard: 48
 *  Archer:bombard: 4
 *  LaserCannonUnit:bombard: 44
 */

5. 命令模式
//命令模式
//命令模式最初来源于图形化用户界面设计,但现在广泛应用于企业应用设计,特别促进了控制器(请求和分法处理)
//和领域模型(应用逻辑)的分离.说得更简单一点,命令模式有助于系统更好地进行组织,并易于扩展
//Command可以设计成接口,因为它很简单...
//Commands/Command.php
abstract class Command{
    abstract function execute(CommandContext $context);
}  
require_once("Command.php");
class Registry{
    //一个空类...
    static function getAccessManager(){
        return new AccessManager();
    }
}
class AccessManager{
    function login(){
        return new stdClass();
    }
    function getError(){}
}
class LoginCommand extends Command{
    function execute(CommandContext $context){
        $manager=Registry::getAccessManager();
        $user=$context->get('username');
        $user=$context->get('pass');
        //虚构出来的空类空方法
        $user_obj=$manager->login();
        if(is_null($user_obj)){
            $context->setError($manager->getError());
            return false;
        }
        $context->addParam("user", $user);
        return true;
    }
}  
//CommandContext类用来做任务扩增用,在这儿主要功能是传递数据给Command类
class CommandContext{
    private $params=array();
    private $error="";
    function __construct(){
        $this->params=$_REQUEST;
    }
    function addParam($key,$val){
        $this->params[$key]=$val;
    }
    function get($key){
        return $this->params[$key];
    }
    function setError($error){
        $this->error=$error;
    }
    function getError(){
        return $this->error;
    }
}
//客户端代码(用于创建命令)已经调用者代码
class CommandNotFoundException extends Exception{
    
}
//创建命令的工厂
class CommandFactory{
    private static $dir="Commands";
    //根据参数action,以及类文件存放目录$dir动态创建相应的$action+Command类
    static function getCommand($action='default'){
        //匹配是否出现非法字符(非字母数字下划线)
        if(preg_match('/\W/', $action)){
            throw new Exception("Illegal characters in action");
        }
        $class=ucfirst(strtolower($action)."Command");
        $file=self::$dir.DIRECTORY_SEPARATOR."{$class}.php";
        if(!file_exists($file)){
            throw new CommandNotFoundException("File could not be find !");
        }
        require_once("$file");
        if(!class_exists($class)){
            throw new CommandNotFoundException("Class could not be find !");
        }
        return new $class();
    }
}
//调用者,里面包含一个CommandContext对象实例,用于存放web请求的数据
class Controller{
    private $context;
    function __construct(){
        $this->context=new CommandContext();
    }
    function getContext(){
        return $this->context;
    }
    function process(){
        $cmd=CommandFactory::getCommand($this->getContext()->get('action'));
        if(!$cmd->execute($this->context)){
            //处理失败
            print "Faile in process!";
        }else{
            //处理成功,可以显示相应的视图层
            print "Success in process!";
        }
    }
}
$controller=new Controller();
$context=$controller->getContext();
$context->addParam('action', 'Login');
$context->addParam('user', 'cocos');
$context->addParam('pass', 'tiddles');
//controller执行process方法,需要不理解command的意义.
$controller->process();//Success in process
Copy after login


Related labels：
Task model
source：php.cn
Previous article：php中call_user_func函数使用注意事项，calluserfunc Next article：XAMPP:访问phpmyadmin出错的解决方案，xamppphpmyadmin
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Latest Articles by Author
Latest Issues
The page suddenly cannot pull css or bootstrap So I'm developing a page, I did part of it yesterday and it worked great, and today I cont...
From 2024-04-06 21:58:04
0
1
800
How to solve the mysterious white space at the bottom of the page in CSS I'm trying to build a simple webpage using Bootstrap and D3, but I don't know how to get r...
From 2024-04-06 20:22:15
0
1
454
How to use laravel components with livewire lazy placeholder I want to add the skeleton of my laravel component inside a livewire3 placeholder What I h...
From 2024-04-06 20:02:10
0
2
543
Can a workerpool declared in multiple routes still maintain its cpu usage without caring about the threshold I'm hoping to find a node.js system with a workerpool to handle CPU intensive tasks, but I...
From 2024-04-06 19:54:23
0
1
444
What are the best practices for displaying version information in web applications? I'm developing a web application. What are the best practices for displaying version infor...
From 2024-04-06 19:13:16
0
2
476
Related Topics
More>
Popular Recommendations
Popular Tutorials
More>
Related Tutorials
Popular Recommendations
Latest courses
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template