PHP入门-使用面向对象思想开发的图形计算器

本文使用面向对象的思想，做了一个图形计算器的小例子：

1、架构图

2、说明

（1）index.php页面只需要直接调用Form类和Result类

（2）Form类用于输入一个表单

（3）为了实现多态的特性，Result类用于操作数据

3、Shape类

<?php
    abstract class Shape{
        abstract function area();//面积
        abstract function perimeter();//周长
    }

4、Rectangle类

<?php
    class Rectangle extends Shape {
        private $width=0;
        private $height=0;

        function __construct($width,$height){
            $this->width=$width;
            $this->height=$height;
        }

        function area(){
            return $this->width * $this->height;
        }

        function perimeter(){
            return 2*$this->width + 2*$this->height;
        }
}

5、Triangle类

<?php
    class Triangle extends Shape {
        private $side1=0;
        private $side2=0;
        private $side3=0;

        function __construct($side1,$side2,$side3){
            $this->side1=$side1;
            $this->side2=$side2;
            $this->side3=$side3;
        }

        function area(){
            if ($this->isTriangle()){
                $temp=($this->side1 + $this->side2 + $this->side3)/2;
                return sqrt($temp * ($temp - $this->side1) * ($temp - $this->side2) * ($temp - $this->side3) );
            }else{
                return "无法构成三角形";
            }
        }

        function perimeter(){
            if ($this->isTriangle()){
                return $this->side1 + $this->side2 + $this->side3;
            }else{
                return "无法构成三角形";
            }
        }

        //需要验证是否能构成三角形
        function isTriangle(){
            if (($this->side1 + $this->side2 > $this->side3)&&($this->side1 + $this->side3 > $this->side2)&&($this->side2 + $this->side3 > $this->side1)){
                return true;
            }else{
                return false;
            }
        }
}

6、Circle类

<?php
    class Circle extends Shape {
        private $radius=0;

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

        function area(){
            return M_PI * $this->radius * $this->radius;
        }

        function perimeter(){
            return 2 *  M_PI * $this->radius;
        }
}

7、Result类

<?php
    class Result{
        private $shape=null;//形状
        private $result='';//结果

        //通过不同的名字，创建不同的对象
        function __construct(){
            switch ($_POST["subForm"]){
                case "rectangle":
                    $this->shape=new Rectangle($_POST["width"],$_POST["height"]);
                    break;
                case "triangle":
                    $this->shape=new Triangle($_POST["side1"],$_POST["side2"],$_POST["side3"]);
                    break;
                case "circle":
                    $this->shape=new Circle($_POST["radius"]);
                    break;
                default:
                    $this->shape=new Rectangle($_POST["width"],$_POST["height"]);
            }
        }
        function __toString(){
            $this->result.='面积是：'.$this->shape->area();
            $this->result.='周长是：'.$this->shape->perimeter();
            return $this->result;
        }
    }

8、Form类

<?php
    class Form{
        private $index;//位置

        function __construct($index="index.php"){
            $this->index=$index;
        }

        function __toString(){
            $form='<form action="'.$this->index  .'?action='. $_GET["action"]  .'" method="post">';
            switch ($_GET["action"]){
                case "rectangle":
                    $form.=$this->getRectangle();
                    break;
                case "triangle":
                    $form.=$this->getTriangle();
                    break;
                case "circle":
                    $form.=$this->getCircle();
                    break;
                default:
                    $form.=$this->getRectangle();
            }
            $form.='<input type="text" hidden="hidden" name="subForm" value="'.$_GET["action"].'">';
            $form.='<input type="submit" value="计算">';
            $form.='</form>';
            return $form;
        }

        function getRectangle(){
            $rectangle='矩形:<br>';
            $rectangle.='宽度：<input type="text" name="width">'.'<br>';
            $rectangle.='高度：<input type="text" name="height">'.'<br>';
            return $rectangle;
        }
        function getTriangle(){
            $rectangle='三角形:<br>';
            $rectangle.='边一：<input type="text" name="side1">'.'<br>';
            $rectangle.='边二：<input type="text" name="side2">'.'<br>';
            $rectangle.='边三：<input type="text" name="side3">'.'<br>';
            return $rectangle;
        }
        function getCircle(){
            $rectangle='圆形:<br>';
            $rectangle.='半径：<input type="text" name="radius">'.'<br>';
            return $rectangle;
        }
    }

9、index.php

<html lang="cn">
<head>
    <meta charset="UTF-8">
    <title>图形计算</title>
</head>
<body>
    <center>
        <h1>计算图形</h1>
        <a href="index.php?action=rectangle">矩形</a>
        <a href="index.php?action=triangle">三角形</a>
        <a href="index.php?action=circle">圆形</a>
    </center>

    <?php
//        error_reporting(E_ERROR);
//        ini_set("display_errors","Off");  //屏蔽掉PHP警告和错误提示

        //类的自动加载
        function __autoload($className){
            include strtolower($className).".class.php";
        }

        //显示表单
        echo new Form();
        echo '<br><br><br><br>结果：<br>';
        //操作数据
        echo new Result();
    ?>
</body>
</html>