>[success] ### 第四难 VerificationCode验证码 * 验证码可以防止机器人的恶意请求(恶意表单提交、破解密码、刷票、论坛灌水......) * 案例链接：https://pan.baidu.com/s/1kVcOTuv 密码：d6j9  >[success] ### 例子2 * 字体文件下载msjh.ttf 链接：https://pan.baidu.com/s/1jHLpYku 密码：el2k ~~~php <?php class VerificationCode { private $charset = "abcdefghjkmnpqrstuvwxyzABCDEFGHJKMNPQRSTUVWXYZ23456789"; //随机因子 public $code; //验证码 private $codelen = 4; //验证码长度 private $width = 130; //宽度 private $height = 50; //高度 private $img; //图像资源句柄 private $font; //制定字体 private $fontSize = 20; //字体大小 private $fontColor; //字体颜色 public function __construct() { //制定字体 $this->font = 'msjh.ttf';//注意字体路径要写对，否则显示不了图片 } //生成验证码 private function createCode() { $len = strlen($this->charset) - 1; for ($i = 0; $i < $this->codelen; $i++) { $this->code .= $this->charset[mt_rand(0, $len)]; } } //生成背景 private function createBg() { $this->img = imagecreatetruecolor($this->width, $this->height); //imagecreatetruecolor — 新建一个真彩色图像 $color = imagecolorallocate($this->img, mt_rand(157, 255), mt_rand(157, 255), mt_rand(157, 255)); //imagecolorallocate — 为一幅图像分配颜色 imagefilledrectangle($this->img, 0, $this->height, $this->width, 0, $color); } //生成文字 private function createFont() { //每个字符的平均宽度 $x = $this->width / $this->codelen; for ($i = 0; $i < $this->codelen; $i++) { //字体的颜色 $this->fontColor = imagecolorallocate($this->img, mt_rand(0, 156), mt_rand(0, 156), mt_rand(0, 156)); imagettftext($this->img, $this->fontSize, mt_rand(-10, 10), $i * $x + mt_rand(1, 3), $this->height / 1.3, $this->fontColor, $this->font, $this->code[$i]); //imagestring($this->img,5,$i*$x+mt_rand(1,5),5,$this->code[$i],$this->fontColor); } } //生成线条、雪花 private function createDisturb() { for ($i = 0; $i < 6; $i++) { $color = imagecolorallocate($this->img, mt_rand(0, 156), mt_rand(0, 156), mt_rand(0, 156)); imageline($this->img, mt_rand(0, $this->width), mt_rand(0, $this->width), mt_rand(0, $this->width), mt_rand(0, $this->width), $color); //imageline() 用 color 颜色在图像 image 中从坐标 x1，y1 到 x2，y2（图像左上角为 0, 0）画一条线段。 } for ($i = 0; $i < 100; $i++) { $color = imagecolorallocate($this->img, mt_rand(200, 255), mt_rand(200, 255), mt_rand(200, 255)); imagestring($this->img, mt_rand(1, 5), mt_rand(0, $this->width), mt_rand(0, $this->height), '*', $color); //imagestring — 水平地画一行字符串 } } //输出 private function outPut() { header("Content-Type:image/png"); imagepng($this->img); imagedestroy($this->img); } //显示验证码 public function showCode() { $this->createBg(); echo $this->code; $this->createCode(); //$_SESSION['code'] = $this->getCode(); $this->createDisturb(); $this->createFont(); $this->outPut(); } //获取验证码 public function getCode() { return strtolower($this->code); } } $code = new VerificationCode(); $code->showCode(); ~~~