PHP 实现图片验证码

PHP 实现图片验证码

步骤

• 产生随机字符串

• 创建一张简单的图片，设置背景色，文本色

• 再加一些干扰线，干扰素

• 输出图像

• 销毁图像资源

  <?php//PHP生成图片验证码class VerifyImage{  private $verifyCode;  private $image;  //生成随机字串  private function createCode($type=1,$length=4){      if ($type == 1) {          $verifyCode = implode('', range(0, 9));      }elseif ($type == 2) {          $verifyCode = implode('', array_merge(range('a', 'z'),range('A', 'Z')));      }else{          $verifyCode = implode('', array_merge(range('a', 'z'),range(0, 9),range('A', 'Z')));      }      //判断生成字符是否符合要求      if (strlen($verifyCode)<$length) {          return false;      }      //打乱字符串      $verifyCode = str_shuffle($verifyCode);      return substr($verifyCode, 0,$length);  }  //生成图片,并加入干扰线，干扰素  public function createImage($type=1,$length=4,$width = 80,$height = 40){      $verifyCode = $this->createCode($type,$length);      $image = imagecreatetruecolor($width, $height);      //白色背景      $white = imagecolorallocate($image, 255, 255, 255);      //字体颜色      $fontStyle = imagecolorallocate($image, rand(0, 255),rand(0, 255), rand(0, 255));;      imagefill($image, 0, 0, $white);      imagestring($image, 5, 10, 10, $verifyCode, $fontStyle);      //加入干扰点      for($i = 0; $i < 80; $i++) {            $color = imagecolorallocate($image, rand(0, 255), rand(0, 255), rand(0, 255));            imagesetpixel($image, rand(0, $width), rand(0,$height), $color);        }      //干扰线        for($i = 0; $i < 5; $i++) {            $color = imagecolorallocate($image, rand(0, 255), rand(0, 255), rand(0, 255));            imageline($image, rand(0, $width), rand(0, $height), rand(0, $width), rand(0, $height), $color);        }       //输出图片      header("Content-type: image/png");       imagepng($image);      //释放资源      imagedestroy($image);  }}$im = new VerifyImage();;$im->createImage(3);?>

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