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
http://www.bkjia.com/phpjc/478390.htmlwww.bkjia.comtruehttp://www.bkjia.com/phpjc/478390.htmltecharticle?php /** * 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 $coden...