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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