图形（周长和面积）计算器

第一步：界面设计

function __autoload($className){

include $className.’.class.php’;

}

echo new Form();

if($_POST[‘sub’]){

echo new Result();

}

?>

第二步：生成表单类

/*

* 表单类：

*

* 功能：根据不同的条件，输出不同样式的表单

*

* 核心思想：__toString()方法的使用

*

*/

class Form {

private $action;

private $shape;

function __construct($action=’index.php’){

$this->action=$action;

$this->shape=isset($_REQUEST[‘action’])?$_REQUEST[‘action’]:’rect’;

}

function __toString(){

$form='

return $form;

}

private function getRect(){

$input='请输入矩形的宽度和高度:

’;

$input.='shape.'”>’;

$input.=’长度：long ” value=”‘.$_POST[‘long’].'”>

’;

$input.=’宽度：

’;

return $input;

}

private function getTriangle(){

$input='请输入三角形的三条边:

’;

$input.='shape.'”>’;

$input.=’第一条边：

’;

$input.=’第二条边：

’;

$input.=’第三条边：

’;

return $input;

}

private function getCircle(){

$input='请输入圆形的半径:

’;

$input.='shape.'”>’;

$input.=’半径：

’;

return $input;

}

}

第三步：生成结果类

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;

}

}

function __toString(){

if($this->shape){

$result=$this->shape->shapeName.’的周长为：’.$this->shape->C().’;面积为：’.$this->shape->S();

return $result;

}else {

return ‘没有这个形状’;

}

}

}

第四步：生成抽象类——定义功能模块开发规范

abstract class Shape {

var $shapeName;

abstract function S();

abstract function C();

protected function validate($value,$ message ){

if ($value==” || !is_numeric($value) || $value < 0) {

echo ‘’.$message.’必须为非负数且不能为空！’;

return false;

}else {

return true;

}

}

}

第五步：定义各个图像类

1. 矩形类

class Rect extends Shape{

private $width;

private $long;

function __construct(){

$this->shapeName=’矩形’;

if($this->validate($_POST[‘width’], ‘矩形的宽’) && $this->validate($_POST[‘long’], ‘矩形的长’)){

$this->width=$_POST[‘width’];

$this->long=$_POST[‘long’];

}else{

exit();

}

}

function C(){

$C=($this->long+$this->width)*2;

return $C;

}

function S(){

$S=$this->long*$this->width;

return $S;

}

}

2. 三角形类

class Triangle extends Shape{

private $a;

private $b;

private $c;

function __construct(){

$this->shapeName=’三角形’;

if($this->check()){

$this->a=$_POST[‘side1’];

$this->b=$_POST[‘side2’];

$this->c=$_POST[‘side3’];

}else {

exit();

}

}

function C(){

$C=$this->a+$this->b+$this->c;

return $C;

}

function S(){//利用”海伦公式”

$p=($this->a+$this->b+$this->c)/2;

$S=sqrt($p*($p-$this->a)*($p-$this->b)*($p-$this->c));

return $S;

}

private function check(){

//两边之和大于第三边

//两边之差大于第三边

}

}

3. 圆形类

class Circle extends Shape{

private $r;

function __construct(){

$this->shapeName=’圆形’;

if ($this->validate($_POST[‘radius’], ‘圆的半径’)) {

$this->r=$_POST[‘radius’];

}else {

exit();

}

}

function C(){

$C=2*round( pi (),0)*$this->r;

return $C;

}

function S(){

$S=round(pi(),0)*pow($this->r, 2);

return $S;

}

}