/** * 验证码类，用于产生各种验证码 */class captcha{ /** * 生成验证码 * @param int $length 码字符长度 * @param int $width 宽度 * @param int $height 长度 * @param string $type 类型 * @return */ public static function getCode($length=4,$width=50,$height=22,$type='png') { //session_start(); $randval = self::randString($length); //$_SESSION['captcha']= $randval; $width = ($length*9+10)>$width?$length*9+10:$width; if ( $type!='gif' && function_exists('imagecreatetruecolor')) { $im = @imagecreatetruecolor($width,$height); }else { $im = @imagecreate($width,$height); } $r = Array(225,255,255,223); $g = Array(225,236,237,255); $b = Array(225,236,166,125); $key = mt_rand(0,3); $backColor = imagecolorallocate($im, $r[$key],$g[$key],$b[$key]); //背景色（随机） $borderColor = imagecolorallocate($im, 100, 100, 100); //边框色 $pointColor = imagecolorallocate($im,mt_rand(0,255),mt_rand(0,255),mt_rand(0,255)); //点颜色 @imagefilledrectangle($im, 0, 0, $width - 1, $height - 1, $backColor); @imagerectangle($im, 0, 0, $width-1, $height-1, $borderColor); $stringColor = imagecolorallocate($im,mt_rand(0,200),mt_rand(0,120),mt_rand(0,120)); // 干扰 for($i=0;$i<10;$i++){ $fontcolor=imagecolorallocate($im,mt_rand(0,255),mt_rand(0,255),mt_rand(0,255)); imagearc($im,mt_rand(-10,$width),mt_rand(-10,$height),mt_rand(30,300),mt_rand(20,200),55,44,$fontcolor); } for($i=0;$i<25;$i++){ $fontcolor=imagecolorallocate($im,mt_rand(0,255),mt_rand(0,255),mt_rand(0,255)); imagesetpixel($im,mt_rand(0,$width),mt_rand(0,$height),$pointColor); } @imagestring($im, 10, 20, 10, $randval, $stringColor); header("Content-type: Image/".$type); $ImageFun='Image'.$type; $ImageFun($im); imagedestroy($im); return $randval; }}以上是完整的生成图片验证码的方法，下面是使用该方法生成验证码：
include "../lib/captcha.class.php"; $captcha = new captcha(); $checkCode = $captcha->getCode(4,75,32); echo $checkCode;
最后在页面显示的效果就是这样，刷新一次重新生成一个：
