<?php//设置 验证码高度宽度\上面字符个数$img_w = 70;$img_h = 22;$font = 5;$char_len = 5;//数组合并， range()函数返回一个范围数组$char = array_merge ( range ( 'a', 'z' ), range ( 'A', 'Z' ), range ( '1', '9' ) );$rand_keys = array_rand ( $char, $char_len ); //随机从数组中取指定个数的元素,生成键值if ($char_len == 1) { //若只有一个数，则array_rand()返回非数组类型 $rand_keys = array ($rand_keys );}shuffle($rand_keys);//可以不用$code = '';foreach ( $rand_keys as $k ) { $code .= $char [$k];}session_start ();$_SESSION ['captcha'] = $code; //添加线、色//创建新图像$img = imagecreatetruecolor ( $img_w, $img_h );//分配颜色$bg_color = imagecolorallocate ( $img, 0xcc, 0xcc, 0xcc );//画布背景色imagefill ( $img, 0, 0, $bg_color );//干扰线for($i = 0; $i < 300; ++$i) { $color = imagecolorallocate ( $img, mt_rand ( 0, 255 ), mt_rand ( 0, 255 ), mt_rand ( 0, 255 ) ); imagesetpixel ( $img, mt_rand ( 0, $img_w ), mt_rand ( 0, $img_h ), $color );}for($i = 0; $i <= 10; ++ $i) { //设置直线颜色 $color = imageColorAllocate ( $img, mt_rand ( 0, 255 ), mt_rand ( 0, 255 ), mt_rand ( 0, 255 ) ); //在$img图像上随机画一条直线 imageline ( $img, mt_rand ( 0, $img_w ), mt_rand ( 0, $img_h ), mt_rand ( 0, $img_w ), mt_rand ( 0, $img_h ), $color ); //imagesetpixel($img,mt_rand(0,$img_w),mt_rand(0,$img_h),$color);} //加加框$rect_color = imagecolorallocate ( $img, 0x90, 0x90, 0x90 );imagerectangle ( $img, 0, 0, $img_w - 1, $img_h - 1, $rect_color );$str_color = imagecolorallocate ( $img, mt_rand ( 0, 100 ), mt_rand ( 0, 100 ), mt_rand ( 0, 100 ) );$font_w = imagefontwidth ( $font );$font_h = imagefontheight ( $font );$str_len = $font_w * $char_len;imagestring ( $img, $font, ($img_w - $str_len) / 2, ($img_h - $font_h) / 2, $code, $str_color );

$str_color = imageColorAllocate($img, mt_rand(0, 100), mt_rand(0, 100),mt_rand(0, 100));//设定字符串位置$font_w = imageFontWidth($font);//字体宽$font_h = imageFontHeight($font); //字体高$str_w = $font_w * $char_len; //字符串宽imageString($img, $font, ($img_w-$str_w)/2, ($img_h-$font_h)/2, $code, $str_color);echo 'ddd'; //输出影响生成图片，查找了大半天的原因终于找到了ob_clean(); //也可以加上这句，这样前面有输出，清除输出缓存//生成图片header ( 'Content-Type: image/png' );//header前不能加任何输出或加ob_clean()清除imagepng($img);//----4 销毁画布imagedestroy($img);