PHP使用CURL上传文件
用curl上传文件的话很方便，什么header,post串都不用生成了,用fsockopen要写一堆
curl:

$file = array("upimg"=>"@E:/png.png");//文件路径，前面要加@，表明是文件上传.
$curl = curl_init("http://localhost/a.php");
curl_setopt($curl,CURLOPT_POST,true);
curl_setopt($curl,CURLOPT_POSTFIELDS,$file);
curl_exec($curl);

fsockopen

$uploadFile = file_get_contents("E:/png.png");
$boundary   = md5(time());

$postStr .="--".$boundary."\r\n";//边界开始,注意默认比header定义的boundary多两个'-'
$postStr .="Content-Disposition: form-data; name=\"upimg\"; filename=\"E:/png.png\"\r\n";
$postStr .="Content-Type: image/png\r\n\r\n";
$postStr .=$uploadFile."\r\n";
$postStr .="--".$boundary."\r\n";//边界结束
fwrite($fp,"POST /a.php HTTP/1.0\r\n");
fwrite($fp,"Content-Type: multipart/form-data; boundary=".$boundary."\r\n");
fwrite($fp,"Content-length:".strlen($postStr)."\r\n\r\n");
fwrite($fp,$postStr);
while (!feof($fp)){
     echo fgets($fp, 128);
}
fclose($fp);

print_r($_FILES);