产生验证码

<?php 
//Session保存路径
$sessSavePath = dirname(__FILE__)."/data/sessions/";
if(is_writeable($sessSavePath) && is_readable($sessSavePath)){ 
	session_save_path($sessSavePath);
}
$letter = "";
//获取随机数字
for ($i=0; $i<3; $i++) {
  $letter .= chr(mt_rand(48,57));
}
//获取随机字母
for ($i=0; $i<3; $i++) {
  $letter .= chr(mt_rand(65,90));
}
//重构字符顺序
$strs = str_split($letter);
shuffle ($strs);
$rndstring = "";
while (list (, $str) = each ($strs)) {
  $rndstring .= $str;
}
//获取随机字符
//$letras = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
//for($i=0; $i<6; $i++) {
	//$rndstring .= chr(mt_rand(48,90));
//	$rndstring .= $letras[rand(0, 35)];
//}

//如果支持GD，则绘图
if(function_exists("imagecreate"))
{
	//PutCookie("dd_ckstr",strtolower($rndstring),1800,"/");
	session_register('dd_ckstr');
	$_SESSION['dd_ckstr'] = strtolower($rndstring);
	$rndcodelen = strlen($rndstring);
  //图片大小
  //$im = imagecreate(85,20);
  $im = imagecreatefromgif("code.gif");
  //字体
  $font_type = dirname(__FILE__)."/data/ant1.ttf";
  //背景颜色
  //$backcolor = imagecolorallocate($im,190,190,120); 
  //边框色
  //$iborder = ImageColorAllocate($im, 0x71,0x76,0x67); 

  //字体色
  //不支持 imagettftext
  $fontColor = ImageColorAllocate($im, 0xff,0xff,0xff); 
  
  //支持 imagettftext
  $fontColor2 = ImageColorAllocate($im, 0xff,0xff,0xff);
  //阴影
  $fontColor1 = ImageColorAllocate($im, 0x33,0x33,0x33); 
  
  //杂点背景线
  //$lineColor1 = ImageColorAllocate($im, 130,220,245);
  //$lineColor2 = ImageColorAllocate($im, 225,245,255);
  
  //背景线
  //for($j=3; $j<=16; $j=$j+3) imageline($im,2,$j,83,$j,$lineColor1);
  //for($j=2; $j<83; $j=$j+(mt_rand(3, 10))) imageline($im,$j,2,$j-6,18,$lineColor2);
 
  //边框
  //imagerectangle($im, 0, 0, 84, 19, $iborder);
  
  $strposs = array();
  //文字
  for($i=0;$i<$rndcodelen;$i++){
	  if(function_exists("imagettftext")){
	  	$strposs[$i][0] = $i*13+6;
	  	$strposs[$i][1] = mt_rand(15,18);
	  	imagettftext($im, 5, 5, $strposs[$i][0]+1, $strposs[$i][1]+1, $fontColor1, $font_type, $rndstring[$i]);
	  } else{
	  	imagestring($im, 5, $i*13+6, mt_rand(2, 4), $rndstring[$i], $fontColor);
	  }
  }
  
  
  //文字
  for($i=0;$ijpg ->png
  if(function_exists("imagejpeg")){
  	header("content-type:image/jpeg\r\n");
  	imagejpeg($im);
  }else{
    header("content-type:image/png\r\n");
  	imagepng($im);
  }
  ImageDestroy($im);

}else{ //不支持GD，只输出字母 ABCD	
	//PutCookie("dd_ckstr","abcd",1800,"/");
	session_register('dd_ckstr');
	$_SESSION['dd_ckstr'] = "abcd";
	header("content-type:image/jpeg\r\n");
	header("Pragma:no-cache\r\n");
  header("Cache-Control:no-cache\r\n");
  header("Expires:0\r\n");
	$fp = fopen("./vdcode.jpg","r");
	echo fread($fp,filesize("./vdcode.jpg"));
	fclose($fp);
}
?>