PHP获取验证码图片到本地，支持png、gif、jpg三种格式的验证码。在实现时，PHP判断图片格式是使用的php内置的exif_imagetype函数，确实比较方便，学习PHP的不妨可参考下本代码：
view sourceprint?01
02header("Content-type:image/png");
03set_time_limit(0);//设置超时时间
04$url = $_GET['url'];
05$url = "http://vcer.baidu.com/verify";
06if(empty($url)){
07 echo "没有图片";
08 die;
09}
10$imginfo = GetImageSize ( $url );
11$type = exif_imagetype($url);
12$imgw = $imginfo [0];
13$imgh = $imginfo [1];
14$bg = imagecreatetruecolor($imgw,$imgh);
15if($type==IMAGETYPE_GIF){
16 $image = imagecreatefromgif($url);
17}elseif($type==IMAGETYPE_JPEG){
18 $image = imagecreatefromjpeg($url);
19}elseif($type==IMAGETYPE_PNG){
20 $image = imagecreatefrompng($url);
21}
22imagecolorallocate($image,255,255,255);
23imagecopy($bg,$image,0,0, 0,0,$imgw,$imgh);
24imagedestroy($image);
25ImagePng($bg);
26?>