效果：
index.php
<!DOCTYPE html>
<html>
<head>
<title>图形计算（使用面向对象技术开发）</title>
<meta http-equiv="content" content="text/html" charset="utf-8" />
</head>
<body>
<center> <!--居中-->
<h1>图形（周长&面积）计算器</h1>
<!--计算图形的链接-->
<a href="index.php?action=rect">矩形</a>||
<a href="index.php?action=triangle">三角形</a>||
<a href="index.php?action=circle">圆形</a>
<hr> <!--创建一条水平分隔线-->
</center>
<?php
//错误报告处理
//error_reporting(E_ALL & ~E_NOTUCE);
//自动加载需要的类文件
function __autoload($className){
//strtolower()函数，把类名转化为小写
include strtolower($className).".class.php";
}
echo new Form();
if(isset($_POST["sub"])){
echo new Result();
}
?>
</body>
</html>
form.class.php
<?php class Form{ private $action; private $shape; //在PHP5中的构造方法 function __construct($action=""){ $this->action=$action; $this->shape=isset($_REQUEST["action"])?$_REQUEST["action"]:"rect"; } //在直接输出对象引用的时候自动调用 function __toString(){ $form='<form action="'.$this->action.'" method="post">'; //echo $this->shape; switch($this->shape){ case "rect": //要加到表单里面，要返回字符串 $form.=$this->getRect(); break; case "triangle": $form.=$this->getTriangle(); break; case "circle": $form.=$this->getCircle(); break; default: $form.='请选择一个形状<br>'; } $form.='<input type="submit" name="sub" value="计算">'; $form.='</form>'; return $form; } //得到矩形的方法 private function getRect(){ $input='<b>请输入矩形的宽度和高度：</b><p>'; $input.='宽度：<input type="text" name="width" value="'.$_POST["width"].'"><br>'; $input.='高度：<input type="text" name="height" value="'.$_POST["height"].'"><br>'; $input.='<input type="hidden" name="action" value="rect">'; return $input; } //得到三角形的方法 private function getTriangle(){ $input='<b>请输入三角形的三条边：</b><p>'; $input.='第一条边：<input type="text" name="side1" value="'.$_POST["side1"].'"><br>'; $input.='第二条边：<input type="text" name="side2" value="'.$_POST["side2"].'"><br>'; $input.='第三条边：<input type="text" name="side3" value="'.$_POST["side3"].'"><br>'; $input.='<input type="hidden" name="action" value="triangle">'; return $input; } //得到圆形的方法 private function getCircle(){ $input='<b>请输入圆形的半径：</b><p>'; $input.='半径：<input type="text" name="radius" value="'.$POST["radius"].'"><br>'; $input.='<input type="hidden" name="action" value="circle">'; return $input; } } ?>
shape.class.php
<?php abstract class Shape{ public $shapeName; abstract function area(); abstract function perimeter(); //验证 protected function validate($value,$message="形状"){ if($value==""||!is_numeric($value)||$value<0){ echo '<font color="red">'.$message.'必须为非负值的数字，并且不能为空！</font><br>'; return false; }else{ return true; } } } ?>
result.class.php
<?php class Result{ private $shape; function __construct(){ switch ($_POST['action']) { case 'rect': $this->shape=new Rect(); break; case 'triangle': $this->shape=new Triangle(); break; case 'circle': $this->shape=new Circle(); break; default: $this->shape=false; break; } } //在直接输出对象引用的时候自动调用 function __toString(){ if($this->shape){ $result=$this->shape->shapeName."的周长：".$this->shape->perimeter().'<br>'; $result.=$this->shape->shapeName."的面积：".$this->shape->area().'<br>'; return $result; }else{ return "没有这个形状<br>"; } } } ?>
Rect.class.php
<?php class Rect extends Shape{ private $width=0; private $height=0; function __construct(){ $this->shapeName="矩形"; if($this->validate($_POST["width"],'矩形的宽') & $this->validate($_POST["height"],"矩形的长")){ $this->width=$_POST["width"]; $this->height=$_POST["height"]; }else{ exit; } } //面积 function area(){ return $this->width*$this->height; } //周长 function perimeter(){ return 2*($this->width+$this->height); } } ?>
Triangle.class.php
<?php class Triangle extends Shape{ private $side1=0; private $side2=0; private $side3=0; function __construct(){ $this->shapeName="三角形"; if($this->validate($_POST["side1"],'三角形的第一条边') & $this->validate($_POST["side2"],"三角形的第二条边") & $this->validate($_POST["side3"],"三角形的第三条边")){ $this->side1=$_POST["side1"]; $this->side2=$_POST["side2"]; $this->side3=$_POST["side3"]; if(!$this->validateSum()){ echo '<font color="red">三角形的两边之和必须大于第三边！</font><br>'; exit; } }else{ exit; } } //海伦公式 function area(){ $s=($this->side1+$this->side2+$this->side3)/2; return sqrt($s*($s-$this->side1)*($s-$this->side2)*($s-$this->side3)); } function perimeter(){ return $this->side1+$this->side2+$this->side3; } //验证两边之和大于第三边 private function validateSum(){ $condition1=($this->side1 + $this->side2)> $this->side3; $condition2=($this->side1 + $this->side3)>$this->side2; $condition3=($this->side2 + $this->side3)>$this->side1; if($condition1 & $condition2 & $condition3){ return true; }else{ return false; } } } ?>
Circle.class.php
<?php class Circle extends Shape{ private $radius=0; function __construct(){ $this->shapeName="圆形"; if($this->validate($_POST["radius"],'圆的半径')){ $this->radius=$_POST["radius"]; }else{ exit; } } function area(){ return pi()*$this->radius*$this->radius; } function perimeter(){ return 2*pi()*$this->radius; } } ?>