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php 验证码类

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 /**
  * 验证码类
  * chaojie2008@126.com
  * 2012-02-09
  * */
 class Vailimg {
         private $width;                               //验证码图片的宽度
         private $height;                               //验证码图片的高度
         private $codeNum;                            //验证码字符的个数
         private $checkCode;                           //验证码字符
         private $image;                               //验证码画布
 
         /* 构造方法用来实例化验证码对象,并为一些成员属性初使化        */
         /* 参数width: 设置验证码图片的宽度,默认宽度值为60像素        */
         /* 参数height: 设置验证码图片的高度,默认高度值为20像素        */
         /* 参数codeNum: 设置验证码中字母和数字的个数,默认个数为4个  */
         function __construct($width=60, $height=20, $codeNum=4) {
             $this->width=$width;                     //为成员属性width初使化
             $this->height=$height;                     //为成员属性height初使化
             $this->codeNum=$codeNum;               //为成员属性codeNum初使化
             $this->checkCode=$this->createCheckCode();  //为成员属性checkCode初使化
         }
         function showImage(){                       //通过访问该方法向浏览器中输出图像
             $this->getCreateImage();                 //调用内部方法创建画布并对其进行初使化
             $this->outputText();                     //向图像中输出随机的字符串
             $this->setDisturbColor();                 //向图像中设置一些干扰像素
             $this->outputImage();                    //生成相应格式的图像并输出
         }
         function getCheckCode(){                     //访问该方法获取随机创建的验证码字符串
             return $this->checkCode;                 //返回成员属性$checkCode保存的字符串
         }
         private function getCreateImage(){              //用来创建图像资源,并初使化背影
             $this->image=imageCreate($this->width,$this->height);
             $back=imageColorAllocate($this->image, 255, 255, 255);
             $border=imageColorAllocate($this->image, 0, 0, 0);
             imageRectangle($this->image,0,0,$this->width-1,$this->height-1,$border);
         }
         private function createCheckCode(){           //随机生成用户指定个数的字符串
             for($i=0;$icodeNum;$i++) {
                 $number=rand(0,2);
                 switch($number){
                     case 0 : $rand_number=rand(48,57);break;    //数字
                     case 1 : $rand_number=rand(65,90);break;    //大写字母
                     case 2 : $rand_number=rand(97,122);break;   //小写字母
                 }
                 $ascii=sprintf("%c",$rand_number);
                 $ascii_number=$ascii_number.$ascii;
             }   
             return $ascii_number;   
         }   
         private function setDisturbColor() {    //设置干扰像素,向图像中输出不同颜色的100个点
             for ($i=0;$i                  $color = imagecolorallocate($this->image, rand(0,255), rand(0,255), rand(0,255));
                  imagesetpixel($this->image,rand(1,$this->width-2),rand(1,$this->height-2),$color);
             }
         }
         private function outputText() {       //随机颜色、随机摆放、随机字符串向图像中输出
             for ($i=0;$icodeNum;$i++) {
                  $bg_color = imagecolorallocate($this->image, rand(0,255), rand(0,128), rand(0,255));
                  $x = floor($this->width/$this->codeNum)*$i+3;
                  $y = rand(0,$this->height-15);
                  imagechar($this->image, 5, $x, $y, $this->checkCode[$i], $bg_color);
               }
         }
 
         private function outputImage(){              //自动检测GD支持的图像类型,并输出图像
             if(imagetypes() & IMG_GIF){          //判断生成GIF格式图像的函数是否存在
                 header("Content-type: image/gif");  //发送标头信息设置MIME类型为image/gif
                 imagegif($this->image);           //以GIF格式将图像输出到浏览器
             }elseif(imagetypes() & IMG_JPG){      //判断生成JPG格式图像的函数是否存在
                 header("Content-type: image/jpeg"); //发送标头信息设置MIME类型为image/jpeg
                 imagejpeg($this->image, "", 0.5);   //以JPEN格式将图像输出到浏览器
             }elseif(imagetypes() & IMG_PNG){     //判断生成PNG格式图像的函数是否存在
                 header("Content-type: image/png");  //发送标头信息设置MIME类型为image/png
                 imagepng($this->image);          //以PNG格式将图像输出到浏览器
             }elseif(imagetypes() & IMG_WBMP){   //判断生成WBMP格式图像的函数是否存在
                  header("Content-type: image/vnd.wap.wbmp");   //发送标头为image/wbmp
                  imagewbmp($this->image);       //以WBMP格式将图像输出到浏览器
             }else{                              //如果没有支持的图像类型
                 die("PHP不支持图像创建!");    //不输出图像,输出一错误消息,并退出程序
             }   
         }
         function __destruct(){                      //当对象结束之前销毁图像资源释放内存
             imagedestroy($this->image);            //调用GD库中的方法销毁图像资源
         }
 }
 ?>
 
 摘自chaojie2009的专栏

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