《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

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>';
}
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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>';
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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';
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执行效果：

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);
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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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