《php从零开始开发属于自己的php框架》课程笔记1——MVC与单例模式

╰半橙微兮° 2023-01-11 13:01 99阅读 0赞

## 1.MVC实例 ##

建库建表sql：

SET NAMES utf8;
    SET time_zone = '+00:00';
    SET foreign_key_checks = 0;
    SET sql_mode = 'NO_AUTO_VALUE_ON_ZERO';
    
    DROP DATABASE IF EXISTS `edu`;
    CREATE DATABASE IF NOT EXISTS `edu` DEFAULT CHARSET = `utf8`;
    USE `edu`;
    
    DROP TABLE IF EXISTS `student`;
    CREATE TABLE `student` (
      `id` int(4) NOT NULL AUTO_INCREMENT COMMENT '主键id',
      `name` varchar(50) NOT NULL COMMENT '姓名',
      `email` varchar(100) NOT NULL COMMENT '邮箱',
      `course` varchar(100) NOT NULL COMMENT '课程',
      `grade` int(4) NOT NULL COMMENT '成绩',
      `create_time` int(10) NOT NULL COMMENT '创建时间',
      `update_time` int(10) NOT NULL COMMENT '更新时间',
      PRIMARY KEY (`id`)
    ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='学生信息表';
    
    INSERT INTO `student` (`id`,`name`,`email`,`course`,`grade`,`create_time`,`update_time`) 
    VALUES
    (1,'郭靖','guojing@php.cn','php',80,1505054471,1505054471),
    (2,'黄蓉','huangrong@php.cn','mysql',88,1505054471,1505054471),
    (3,'杨康','yangkang@php.cn','mysql',67,1505054471,1505054471),
    (4,'洪七','hongqi@php.cn','php',35,1505054471,1505054471),
    (5,'老顽童','laowantong@php.cn','html',78,1505054471,1505054471),
    (6,'欧阳峰','ouyangfeng@php.cn','mysql',56,1505054471,1505054471),
    (7,'杨过','yangguo@php.cn','php',89,1505054471,1505054471),
    (8,'小龙女','xiaolongnv@php.cn','html',800,1505054471,1505054471),
    (9,'张无忌','zhangwuji@php.cn','mysql',63,1505054471,1505054471),
    (10,'赵敏',	'zhaomin@php.cn','php',	80,1505054471,1505722385);

model.php：

<?php
    /** * 获取数据 Model 模型层 */
    $conn = mysqli_connect('localhost', 'root', '123456', 'edu');
    $result = mysqli_query($conn, "SELECT * FROM student");
    if ($result && mysqli_num_rows($result) > 0) { 
        $rows = mysqli_fetch_all($result, MYSQLI_ASSOC); // $rows是二维数组
    } else { 
        echo '<h2>没有数据返回</h2>';
    }

view.php：

<?php
    
    /** * 显示数据 View 视图层 */
    echo '<h2 align="center">学生信息表</h2>';
    echo '<table border="1" cellspacing="0" cellpadding="5" align="center" width="60%">';
    echo '<tr align="center" bgcolor="#87ceeb"><th>id</th><th>姓名</th><th>邮箱</th><th>课程</th><th>成绩</th></tr>';
    foreach ($rows as $row) { 
        echo '<tr align="center">';
        echo '<td>'.$row['id'].'</td><td>'.$row['name'].'</td><td>'.$row['email'].'</td><td>'.$row['course'].'</td><td>'.$row['grade'].'</td>';
        echo '</tr>';
    }
    echo '</table>';

mvc.php：

<?php
    /** * mvc编程思想 * 控制器：Controller * 获取并显示，实现数据与视图之间的整合 */
    
    // 获取数据 Model 模型层
    include_once 'model.php';
    
    // 显示数据 View 视图层
    include_once 'view.php';

执行效果：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VzZXJuYW1lNjY2_size_16_color_FFFFFF_t_70]

## 2.单例模式 ##

<?php
    //单例模式：确保仅生成当前类的唯一实例
    /** * 单例模式 */
    
    class Demo
    { 
        // 1.静态私有属性，保存当前类的实例
        private static $instance = null;
    
        // 2.构造方法私有化，禁止外部用new来创建类实例
        private function __construct()
        { 
        }
    
        // 3.克隆方法私有化，禁止从外部克隆来生成本类的实例
        private function __clone()
        { 
            // TODO: Implement __clone() method.
        }
    
        // 4.生产当前类的唯一实例
        // 因为这个方法要使用静态属性，所以必须声明为静态
        public static function getInstance()
        { 
            // 如果不是当前类的实例，那么实例化当前类创建新实例
            if (!self::$instance instanceof self) { 
                self::$instance = new self();
            }
            return self::$instance;
        }
    }
    
    //$obj1 = new Demo();
    //$obj2 = new Demo();
    //$obj3 = new Demo();
    //$obj4 = new Demo();
    // 对象间的复制
    //$obj5 = $obj4; // 引用赋值
    //$obj6 = clone $obj4;
    
    //var_dump($obj1, $obj2, $obj3, $obj4, $obj5);
    
    $obj1 = Demo::getInstance();
    $obj2 = Demo::getInstance();
    $obj3 = Demo::getInstance();
    $obj4 = Demo::getInstance();
    $obj5 = Demo::getInstance();
    
    var_dump($obj1, $obj2, $obj3, $obj4, $obj5);

执行效果：

object(Demo)#1 (0) {  } object(Demo)#1 (0) {  } object(Demo)#1 (0) {  } object(Demo)#1 (0) {  } object(Demo)#1 (0) {  }

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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VzZXJuYW1lNjY2_size_16_color_FFFFFF_t_70]: /images/20221119/b3c1c5f9c78645458b905b763b346a98.png