


Verification code generation and application examples_PHP tutorial
验证码生成与应用实例
在写用户验证页面,如注册,登录的时候,为了加强用户登录的安全性,添加验证码验证。
验证码通过gd生成png图片,并把$randval随机数字赋给$_session['login_check_num'],在通过用户输入的$_post进行比较,来判断是否正确。达到需要实现的功能,需要修改php教程.ini文件,使php支持gd库。
//调用此页面,如果下面的式子成立,则生成验证码图片
if($_get["action"]=="verifycode")
{
rand_create();
}
//验证码图片生成
function rand_create()
{
//通知浏览器将要输出png图片
header("content-type: image/png");
//准备好随机数发生器种子
srand((double)microtime()*1000000);
//准备图片的相关参数
$im = imagecreate(62,20);
$black = imagecolorallocate($im, 0,0,0); //rgb黑色标识符
$white = imagecolorallocate($im, 255,255,255); //rgb白色标识符
$gray = imagecolorallocate($im, 200,200,200); //rgb灰色标识符
//开始作图
imagefill($im,0,0,$gray);
while(($randval=rand()%100000) $_session["login_check_num"] = $randval;
//将四位整数验证码绘入图片
imagestring($im, 5, 10, 3, $randval, $black);
}
//加入干扰象素
for($i=0;$i $randcolor = imagecolorallocate($im,rand(0,255),rand(0,255),rand(0,255));
imagesetpixel($im, rand()%70 , rand()%30 , $randcolor);
}
//输出验证图片
imagepng($im);
//销毁图像标识符
imagedestroy($im);
}
//检验验证码
function rand_check()
{
if($_post["reg_rand"] == $_session["login_check_num"]){
return true;
}
else{
exit("验证码输入错误");
}
}
?>
验证码,是一种区分用户是计算机和人的公共全自动程序。在captcha测试中,作为服务器的计算机会自动生成一个问题由用户来解答。这个问题可以由计算机生成并评判,但是必须只有人类才能解答。由于计算机无法解答captcha的问题,所以回答出问题的用户就可以被认为是人类。
*/
session_start();
$string = null;
$im = imagecreatetruecolor(60,25); //创建真彩图60*25
$bg = imagecolorallocate($im,255,255,255);//白色背景
imagefill($im,0,0,$bg);填充白色
$x = 5;//
$y = 0;//文字坐标
for($i=0 ; $i<4 ;$i++)
{
$char = mt_rand(0,9);
$string .=$char;
$y = mt_rand(0,10);
$ccolor = imagecolorallocate($im,mt_rand(0,230),mt_rand(0,230),mt_rand(0,230));
imagechar($im,6,$x,$y,$char,$ccolor);//填充文字
$x += mt_rand(10,15);
}
for($i=0 ;$i
{
$x1 = mt_rand(0,80);
$x2 = mt_rand(0,80);
$y1 = mt_rand(0,30);
$y2 = mt_rand(0,30);
$x2 = $x1 +mt_rand(1,5);
$y2 = $y1 +mt_rand(1,5);
$lc = imagecolorallocate($im,mt_rand(0,230),mt_rand(0,230),mt_rand(0,230));
imageline($im,$x1,$y1,$x2,$y2,$lc);//填充线条
}
$_session['code'] = md5($string);
header("content-type:image/jpeg");
imagepng($im);
imagedestroy($im);
更多详细内容请查看:http://www.bKjia.c0m/phper/php-cy/33707.htm
当然我们也可以能过同时我们可以明知php ajax来实例验证功能。

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