超强php验证码

<?php
/*
* @Date 2011-2-24
* @Author hudeyong926
*/
function getCode($length = 32, $mode = 0) {
 switch ($mode) {
  case '1' :
   $str = '123456789';
   break;
  case '2' :
   $str = 'abcdefghijklmnopqrstuvwxyz';
   break;
  case '3' :
   $str = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
   break;
  case '4' :
   $str = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
   break;
  case '5' :
   $str = 'ABCDEFGHIJKLMNPQRSTUVWXYZ123456789';
   break;
  case '6' :
   $str = 'abcdefghijklmnopqrstuvwxyz1234567890';
   break;
  case '7' ://中文验证码
   break;
  default :
   $str = 'ABCDEFGHIJKLMNPQRSTUVWXYZabcdefghijkmnpqrstuvwxyz23456789';
   break;
 }
 $result = '';

 for($i = 0; $i < $length; $i ++) {
  if ($mode == 7) {
   $str [$i] = chr ( mt_rand ( 176, 215 ) ) . chr ( mt_rand ( 161, 249 ) );
   $str [$i] = iconv ( "GB2312", "UTF-8", $str [$i] ); //imagettftext是utf-8的,所以先转换下
   $result .= $str [$i];
  } else {
   $l = strlen ( $str ) - 1;
   $num = mt_rand ( 0, $l );
   $result .= $str [$num];
  }
 }
 return $result;
}

//建立验证图片
function createAuthNumImg($randStr, $fontName, $imgW = 100, $imgH = 40) {
 header ( "content-type: image/png" );
 $image = imagecreate ( $imgW, $imgH );
 $fontSize = 20;//字号
 //$green = imagecolorallocate($image,0x6b,0xc1,0x46);
 $gray = imagecolorallocate ( $image, 228, 228, 228 ); //灰色
 $red  = imagecolorallocate ( $image, 255, 102, 204 );//粉色
 $blue = imagecolorallocate($image,0x53,0x68,0xbd);
 $colors = array($red, $gray, $blue);
 
 $color_b = imagecolorallocate ( $image, 0, 0, 0 ); //黑色
 for($i = 0; $i < 1000; $i ++) { //绘背景干扰点
  imagesetpixel ( $image, mt_rand ( 0, $imgW ), mt_rand ( 0, $imgH ), $colors[rand(0,count($colors)-1)]);
 }
 imagerectangle ( $image, 0, 0, $imgW - 1, $imgH - 1, $color_b );//绘制边框
 imagettftext ( $image, $fontSize, 5, 3, 25, $color_b, $fontName, $randStr);///将验证字符绘入图片 字符旋转 
 for($i=0; $i<2; $i++){ //绘背景干扰线
  imageline($image, mt_rand(0,5), mt_rand(6,18), mt_rand(65,$imgW), mt_rand(6,$imgH), $color_b);//一条干扰线
 } 
 imagepng ( $image );
 imagedestroy ( $image );
}

session_start ();
$verifyCode = GetCode ( 5 );
$_SESSION ['VERIFY_CODE'] = $verifyCode ;
createAuthNumImg ( $verifyCode, "font.ttf", 75, 30); //字体存放路径,如果你没有文件就去C:\WINDOWS\Fonts文件中找一个吧。

/** 问答模式
$a=GetCode(2,1); 
$b=GetCode(1,1); 
$passPort = $a."+".$b."=?"; 
$verifyCode = $a+$b; 

$_SESSION ['VERIFY_CODE'] = $verifyCode ; 
createAuthNumImg ( $passPort, "font.ttf", 75, 30);
*/
?>