php图片验证码代码

时间：2015-01-23 来源：西部数据作者：西部数据

在用户验证页面,如注册,登录的时候,为了加强用户登录的安全性,添加验证码验证代码,下面我为各位朋友提供几种不同同类型的php验证代码程序,最后一款是一款使用了验证代码的实例代码,实例代码如下:

date_default_timezone_set('asia/shanghai');

function setcode($len)

{

  $code = '';

  for ($i=0;$i<$len;$i++)//生成随机长度

  {

   $code .= chr(drand());

  }

  return $code;

}

//生成一个随机字符

function drand()

{

  $rand = mt_rand(0,2);

  $str = '';

  switch ($rand)

  {

   case 0: $str = mt_rand(48,57);break;//数字

   case 1: $str = mt_rand(65,90);break;//大写字母

   case 2: $str = mt_rand(97,122);break;//小写字母

  }

  return $str;

}

$_session['checkcode'] = $code = setcode(5);

//php图片验证码原代码，需支持gd2.dll扩展，需修改php.ini后重启iis or ap

session_start();

session_register('safecode');

$type = 'gif';

$width= 40;

$height= 16;

header("content-type: image/".$type);

srand((double)microtime()*1000000);

$randval = randstr(4,"");

if($type!='gif' && function_exists('imagecreatetruecolor')){

     $im = @imagecreatetruecolor($width,$height);

}else{

     $im = @imagecreate($width,$height);

}

     $r = array(225,211,255,223);

     $g = array(225,236,237,215);

     $b = array(225,236,166,125);

     $key = rand(0,3);



     $backcolor = imagecolorallocate($im,$r[$key],$g[$key],$b[$key]);//背景色（随机）

     $bordercolor = imagecolorallocate($im, 0, 0, 0);//边框色

     $pointcolor = imagecolorallocate($im, 255, 170, 255);//点颜色

     @imagefilledrectangle($im, 0, 0, $width - 1, $height - 1, $backcolor);//背景位置

     @imagerectangle($im, 0, 0, $width-1, $height-1, $bordercolor); //边框位置

     $stringcolor = imagecolorallocate($im, 255,51,153);

     for($i=0;$i<=100;$i++){

           $pointx = rand(2,$width-2);

           $pointy = rand(2,$height-2);

           @imagesetpixel($im, $pointx, $pointy, $pointcolor);

     }

     @imagestring($im, 3, 5, 1, $randval, $stringcolor);

     $imagefun='image'.$type;

     $imagefun($im);

     @imagedestroy($im);

     $_session['safecode'] = $randval;

//产生随机字符串

function randstr($len=6,$format='all') {

           switch($format) {

                 case 'all':

                 $chars='abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz0123456789www.111cn.net'; break;

                 case 'char':

                 $chars='abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz'; break;

                 case 'number':

                 $chars='0123456789'; break;

                 default :

                 $chars='abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz0123456789';

                 break;

           }

     $string="";

     while(strlen($string)<$len)

     $string.=substr($chars,(mt_rand()%strlen($chars)),1);

     return $string;

}

//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)<10000);{

        $_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<200;$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;

    } //开源代码phpfensi.com

    else{

        exit("验证码输入错误");

    }

}