封装验证码

使用GD库操作的一般步骤：

1. 创建画布
2. 创建颜色
3. 用GD库的函数去画画
4. 告诉浏览器你的mime类型
5. 输出到浏览器或者保存到本地
6. 销毁

封装验证码类

class Code{
                //验证码个数
            protected $number;
            //验证码类型
            protected $codeType;
            //图像宽度
            protected $width;
            //图像高度
            protected $height;
            //图像资源
            protected $image;
            //验证码字符串
            protected $code;

            public function __construct($number=4,$codeType=2,$width=100,$height=50){
                //初始化自己的成员属性
                $this->number = $number;
                $this->codeType = $codeType;
                $this->width = $width;
                $this->height = $height;
                    //生成验证码
                $this->code = $this->createCode();
                
            }
            public function __destruct(){
                imagedestroy($this->image);
            }

            public function __get($name){
                if($name == 'code'){
                    echo $this->code;
                }else{
                    return false;
                }

            }

            protected function createCode(){
                //通过你的验证码类型生成不同的验证码
                switch($this->codeType){
                    case 0: //纯数字
                        $code = $this->getNumberCode();
                        break;
                    case 1: //纯字母
                        $code = $this->getCharCode();
                        break;
                    case 2: //数字和字母组合
                        $code = $this->getNumCharCode();
                        break;
                    default:
                    die('不支持这种验证码类型');  

                }
                return $code;

            }
            protected function getNumberCode(){
                $str = join('',range(0,9));
                return substr(str_shuffle($str), 0,$this->number);
            }

            protected function getCharCode(){
                $str = join('',range('a', 'z'));
                $str = $str.strtoupper($str);
                return substr(str_shuffle($str), 0,$this->number);

            }
            protected function getNumCharCode(){
                $numStr =join('',range(0, 9));
                $str = join('',range('a', 'z'));
                $str = $numStr.$str.strtoupper($str);
                return substr(str_shuffle($str), 0,$this->number);

            }
            protected function createImage(){
                $this->image = imagecreatetruecolor($this->width, $this->height);

            }
            protected function fillBack(){
                imagefill($this->image,0,0,$this->lightColor());
            }

            protected function lightColor(){
                return imagecolorallocate($this->image, mt_rand(130,250), mt_rand(130,250), mt_rand(130,250));
            }
            protected function darkColor(){
                return imagecolorallocate($this->image, mt_rand(0,120), mt_rand(0,120), mt_rand(0,120));
            }

            protected function drawChar(){
                $width = ceil($this->width/$this->number);
                for($i= 0;$i<$this->number;$i++){
                    $x = mt_rand($i*$width+10,($i+1)*$width-10);
                    $y= mt_rand(0,$this->height-15);
                    imagechar($this->image, 5, $x, $y, $this->code[$i], $this->darkColor());
                }
            }
            protected function drawDisturb(){
                for($i=0;$i<100;$i++){
                    $x= mt_rand(0,$this->width);
                    $y = mt_rand(0,$this->height);
                    imagesetpixel($this->image, $x, $y, $this->lightColor());
                }
            }
            protected function show(){
                header("Content-type:image/png");
                imagepng($this->image);
            }




            public function outImage(){
                //创建画布
                $this->createImage();
                //填充背景色
                $this->fillBack();
                //将验证码画到画布
                $this->drawChar();
                //添加干扰项
                $this->drawDisturb();
                //输出并显示
                $this->show();
            }

    }