实现代码:
- <?php
- //将验证码保存到session里,供全局使用
- session_start();
- $nums = "";
- for($i=0;$i<4;$i++){
- //产生随机数并转换成十六进制
- $nums.=dechex(mt_rand(0,15));
- }
- //将验证码写入session
- $_SESSION['code']=$nums;
- //设置验证码长和宽
- $_width = 60;
- $_height = 20;
- //创建一张图片
- $_img = imagecreatetruecolor($_width,$_height);
- //创建一个白色
- $_white = imagecolorallocate($_img,220,250,250);
- //填充背景
- imagefill($_img,0,0,$_white);
- //随机画6条线条
- for($i=0;$i<6;$i++){
- $_rnd_color = imagecolorallocate($_img,mt_rand(0,255),mt_rand(0,255),mt_rand(0,255));
- imageline($_img,mt_rand(0,$_width),mt_rand(0,$_width),mt_rand(0,$_width),mt_rand(0,$_width),$_rnd_color);
- }
- //随机画出雪花
- for($i=0;$i<60;$i++){
- imagestring($_img,1,mt_rand(1,$_width),mt_rand(1,$_height),"*",imagecolorallocate($_img,mt_rand(200,255),mt_rand(200,255),mt_rand(200,255)));
- }
- //输出验证码
- for($i=0;$i<strlen($_SESSION['code']);$i++){
- imagestring($_img,mt_rand(6,10),$i*$_width/4+mt_rand(1,10),mt_rand(1,$_height/2),$_SESSION['code'][$i],imagecolorallocate($_img,mt_rand(0,100),mt_rand(0,150),mt_rand(0,200)));
- }
- //输出和销毁
- header("Content-Type:image/png");
- imagepng($_img);
- imagedestroy($_img);
- ?>