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php面向对象编程快速入门

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面向对象

把数据及对数据的操作方法放在一起，作为一个相互依存的整体就是对象。对同类对象抽象出其共性，形成类。

class声明类

<?php
//class声明类
class Student{
    public $name = '张三';
    public function print(){
        echo $this->name;
    }
}

$student = new Student();
$student->print();

new 创建对象

<?php
//class声明类
class Student{
    public $name = '张三';
    public function print(){
        echo $this->name;
    }
}

//new 创建对象
$student = new Student();
$student->print();

属性

<?php
//class声明类
class Student{
    //定义公有属性
    public $name = '张三';
    //定义私有属性
    private $age = 25;
    //定义受保护属性
    protected $money = 1000;

    //私有属性，类内部使用
    public function getAge(){
        return $this->age;
    }
    //受保护属性，本类使用，子类不能使用
    public function getMoney(){
        return $this->money;
    }

}

//new 创建对象
$student = new Student();
//获取公有属性
echo $student->name;
//获取私有属性
echo $student->getAge();
//获取受保护属性
echo $student->getMoney();  private $price = '100000';
}

方法

<?php
//class声明类
class Student{
    //定义公有属性
    public $name = '张三';
    //定义私有属性
    private $age = 25;
    //定义受保护属性
    protected $money = 1000;

    //私有属性，类内部使用
    public function getName(){
        return $this->name;
    }

    //私有方法
    private function getAge(){
        return $this->age;
    }
    //受保护方法
    protected function getMoney(){
        return $this->money;
    }
    //类内部调用私有方法和受保护方法
    public function print(){
        echo $this->getAge();
        echo $this->getMoney();
    }

}

//new 创建对象
$student = new Student();
//获取公有属性
echo $student->getName();
//获取私有属性
$student->print();

访问修饰符

public private protected

<?php
//class声明类
class Student{
    //定义公有属性
    public $name = '张三';
    //定义私有属性
    private $age = 25;
    //定义受保护属性
    protected $money = 1000;

    //私有属性，类内部使用
    public function getName(){
        return $this->name;
    }

    //私有方法
    private function getAge(){
        return $this->age;
    }
    //受保护方法
    protected function getMoney(){
        return $this->money;
    }
    //类内部调用私有方法和受保护方法
    public function print(){
        echo $this->getAge();
        echo $this->getMoney();
    }

}

//new 创建对象
$student = new Student();
//获取公有属性
echo $student->getName();
//获取私有属性
$student->print();

this关键字

<?php
//class声明类
class Student{
    //定义公有属性
    public $name = '张三';
    //定义私有属性
    private $age = 25;
    //定义受保护属性
    protected $money = 1000;

    //私有属性，类内部使用
    public function getName(){
        //代表当前类的对象
        return $this->name;
    }

    //私有方法
    private function getAge(){
        //this代表当前类的对象
        return $this->age;
    }
    //受保护方法
    protected function getMoney(){
        return $this->money;
    }
    //类内部调用私有方法和受保护方法
    public function print(){
        echo $this->getAge();
        echo $this->getMoney();
    }

}

//new 创建对象
$student = new Student();
//获取公有属性
echo $student->getName();
//获取私有属性
$student->print();

构造方法

<?php
//class声明类
class Student{

    public $name;
    public $age;

    //构造方法
    public function __construct($name,$age)
    {
        $this->name = $name;
        $this->age = $age;
    }

}

//new 创建对象
$student = new Student('张三', 23);
//获取name
echo $student->name;
//获取age
echo $student->age;

析构方法

<?php
//class声明类
class Student{

    public $name;
    public $age;

    //构造方法
    public function __construct($name,$age)
    {
        $this->name = $name;
        $this->age = $age;
    }

    //析构方法
    public function __destruct()
    {
        echo '析构方法...';
    }

}

//new 创建对象
$student = new Student('张三', 23);
//获取name
echo $student->name;
//获取age
echo $student->age;

static 关键字

<?php
//class声明类
class Student{
    //静态属性
    public static $name = '张三';
    //静态方法
    public static function print(){
        //类内部访问静态方法
        echo self::$name;
    }

}

//访问类的静态属性
echo Student::$name;
//访问类的静态方法
Student::print();

self 关键字

<?php
//class声明类
class Student{
    //静态属性
    public static $name = '张三';
    //静态方法
    public static function print(){
        //类内部访问静态方法
        echo self::$name;
    }

}

//访问类的静态属性
echo Student::$name;
//访问类的静态方法
Student::print();

const 关键字

<?php
//class声明类
class Student{
    //定义类常量
    const ADDRESS = '广东省广州市';

    //方法访问类常量
    public function getAddress(){
        return self::ADDRESS;
    }

}

//访问类常量
echo Student::ADDRESS;
//访问类的方法里的常量
$student = new Student();
echo $student->getAddress();

extends 关键字

<?php
//父类
class Man{
    public $name;
    public $age;

    public function __construct($name, $age)
    {
        $this->name = $name;
        $this->age = $age;
    }
}

//子类，extends继承Man父类
class Student extends Man{
    //年级
    public $grade;

    public function __construct($name, $age, $grade)
    {
        parent::__construct($name, $age);
        $this->grade = $grade;
    }
    //打印属性
    public function print(){
        echo $this->name;
        echo $this->age;
        echo $this->grade;
    }

}

//创建对象，访问打印方法
$student = new Student('张三',25,8);
$student->print();

抽象类

<?php
//抽象类
abstract class Human
{
    //抽象属性
    public $name;
    public $age;

    //抽象方法
    abstract public function print();
}

//父类
class Man extends Human {
    public $name;
    public $age;

    public function __construct($name, $age)
    {
        $this->name = $name;
        $this->age = $age;
    }
    //实现父类抽象方法
    public function print(){
        echo $this->name;
        echo $this->age;
    }
}

//子类，extends继承Man父类
class Student extends Man{
    //年级
    public $grade;

    public function __construct($name, $age, $grade)
    {
        parent::__construct($name, $age);
        $this->grade = $grade;
    }
    //重写父类方法
    public function print(){
        echo $this->name;
        echo $this->age;
        echo $this->grade;
    }

}

//创建对象，访问打印方法
$student = new Student('张三',25,8);
$student->print();

abstract关键字

<?php
//抽象类
abstract class Human
{
    //抽象属性
    public $name;
    public $age;

    //抽象方法
    abstract public function print();
}

//父类
class Man extends Human {
    public $name;
    public $age;

    public function __construct($name, $age)
    {
        $this->name = $name;
        $this->age = $age;
    }
    //实现父类抽象方法
    public function print(){
        echo $this->name;
        echo $this->age;
    }
}

//子类，extends继承Man父类
class Student extends Man{
    //年级
    public $grade;

    public function __construct($name, $age, $grade)
    {
        parent::__construct($name, $age);
        $this->grade = $grade;
    }
    //重写父类方法
    public function print(){
        echo $this->name;
        echo $this->age;
        echo $this->grade;
    }

}

//创建对象，访问打印方法
$student = new Student('张三',25,8);
$student->print();

final 关键字

<?php

//父类
class Man{
    public $name;
    public $age;

    public function __construct($name, $age)
    {
        $this->name = $name;
        $this->age = $age;
    }
    //final方法不能被子类重写
    final public function print(){
        echo $this->name;
        echo $this->age;
    }
}

//final类不能被继承
final class Student extends Man{
    //年级
    public $grade;

    public function __construct($name, $age, $grade)
    {
        parent::__construct($name, $age);
        $this->grade = $grade;
    }

}


//创建对象，访问打印方法
$student = new Student('张三',25,8);
$student->print();

interface关键字和implements关键字

<?php
//Human接口
interface Human
{
    //接口方法
    public function print();
}

//父类 实现Human接口
class Man implements Human {
    public $name;
    public $age;

    public function __construct($name, $age)
    {
        $this->name = $name;
        $this->age = $age;
    }
    //实现接口方法
    public function print(){
        echo $this->name;
        echo $this->age;
    }
}

//final类不能被继承
final class Student extends Man{
    //年级
    public $grade;

    public function __construct($name, $age, $grade)
    {
        parent::__construct($name, $age);
        $this->grade = $grade;
    }

    //重写父类方法
    public function print(){
        echo $this->name;
        echo $this->age;
        echo $this->grade;
    }

}


//创建对象，访问打印方法
$student = new Student('张三',25,8);
$student->print();

自动加载类

student.class.php

<?php
//Human接口
interface Human
{
    //接口方法
    public function print();
}

//父类
class Man implements Human {
    public $name;
    public $age;

    public function __construct($name, $age)
    {
        $this->name = $name;
        $this->age = $age;
    }
    //实现接口方法
    public function print(){
        echo $this->name;
        echo $this->age;
    }
}

//final类不能被继承
final class Student extends Man{
    //年级
    public $grade;

    public function __construct($name, $age, $grade)
    {
        parent::__construct($name, $age);
        $this->grade = $grade;
    }

    //重写父类方法
    public function print(){
        echo $this->name;
        echo $this->age;
        echo $this->grade;
    }

}

index.php

<?php
function autoload($className){
    $filename = "./". $className .".class.php";
    include $filename;
}
//注册给定的函数作为 __autoload 的实现
spl_autoload_register('autoload');


//创建对象，访问打印方法
$student = new student('张三',25,8);
$student->print();

单例模式

<?php

class Student{
    public $name;
    public $age;
    public $grade;

    //私有属性，用于保存实例
    private static $instance;
    //构造方法私有化，防止外部创建实例
    private function __construct(){}

    public function print(){
        echo $this->name;
        echo $this->age;
        echo $this->grade;
    }

    //克隆方法私有化，防止复制实例
    private function __clone(){}

    //公有方法，用于获取实例
    public static function getInstance(){
        //判断实例有无创建，没有的话创建实例并返回，有的话直接返回
        if(!(self::$instance instanceof self)){
            self::$instance = new self();
        }
        return self::$instance;
    }

}


$student = Student::getInstance();
$student->name = '张三';
$student->age = 25;
$student->grade = 6;
$student->print();

工厂模式

<?php
//Man类
class Man{
    public $name;
    public $age;
    public $sex = '男';

    public function __construct($name, $age)
    {
        $this->name = $name;
        $this->age = $age;
    }

    public function print(){
        echo $this->name;
        echo $this->age;
        echo $this->sex;
    }

}
//Woman类
class Woman{
    public $name;
    public $age;
    public $sex = '女';

    public function __construct($name, $age)
    {
        $this->name = $name;
        $this->age = $age;
    }

    public function print(){
        echo $this->name;
        echo $this->age;
        echo $this->sex;
    }
}

//工厂类
class Factory
{
    //工工厂类生产方法
    public static function createObj($type,$name, $age)
    {
        $obj = null;
        switch($type)
        {
            case 'woman':
                $obj =  new Woman($name,$age);
                break;
            case 'man':
                $obj = new Man($name, $age);
                break;
        }
        return $obj;
    }

}

//生产类生产Woman
$woman = Factory::createObj('woman','小红',23);
$woman->print();

//生产类生产man
$man = Factory::createObj('man','张三',25);
$man->print();

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