php?生成验证码解决思路

session_start();<br />$dict = str_split('abcdefghijklmnopqrstuv0123456789');<br />shuffle($dict);<br />$_SESSION['word'] = join('', array_slice($dict, -4));<br /><br />$im = imagecreate(100, 30);<br />$bg = imagecolorallocate($im, 255, 255, 255);<br />$char = imagecolorallocate($im, 0, 0, 0);<br />imagestring($im, 5, 10, 10, $_SESSION['word'], $char);<br />imagegif($im);

<br />	session_start();<br />	$checkCode="";<br />	for($i=0;$i<4;$i++){<br />		$checkCode .=substr('abcdefghijklmnopqrstuvwxyz0123456789', rand(0,35), 1);    // $checkCode.=dechex(rand(1,15));<br />	}<br />	//讲随机验证码保存到session中<br />	$_SESSION['myCheckCode']=$checkCode;<br />	//创建图片，并把随机数画上去<br />	$img=imagecreatetruecolor(100,30);<br />	//背景默认就是黑色<br />	//你可以指定背景颜色<br />	$bgcolor=imagecolorallocate($img,0,0,0);<br />	imagefill($img,0,0,$bgcolor);<br />	//创建新的颜色<br />	$white=imagecolorallocate($img,255,255,255);<br />	$blue=imagecolorallocate($img,0,0,255);<br />	$red=imagecolorallocate($img,255,0,0);<br />	$green=imagecolorallocate($img,255,0,0);<br /><br />	//画出干扰线段<br />	for($i=0;$i<20;$i++){<br />		//更好的方法是颜色随机<br />		imageline($img,rand(0,110),rand(0,30),rand(0,110),rand(0,30),imagecolorallocate($img,rand(0,255),rand(0,255),rand(0,255)));<br />		<br />	}<br />	//画出噪点,自己画.<br />	<br />	//把四个随机值画上去	<br />	imagestring($img,rand(1,5),rand(2,80),rand(2,10),$checkCode,$white);<br />	<br />	//如果要使用中文<br />	//array imagefttext (  string $font_file , string $text [, array $extrainfo ] )<br />	//imagettftext($img,15,10,20,25,$white,"STXINWEI.TTF","北京你好");<br />	//输出<br />	header("content-type: image/png");<br />	imagepng($img);<br /><br />