识别字符串中的外链图片，下载存到本地，并替换图片地址

define('UPLOAD_IMG_PATH','./wordpress/');
//$str = 'sdasda <img src="http://news.xinhuanet.com/forum/2012-07/12/123399677_31n.jpgsdasd" />';
function lx_findPicAndDownload($str){
	preg_match_all('/http://([^/]+/)+[^.]+.(jpg|png|gif)/i',$str, $out);
	for($i=0;$i<count($out[0]);$i++){
		$new_file = lx_downloadAndSaveFile($out[0][$i],$out[2][$i]);
		if($new_file){
			$str = str_replace($out[0][$i],$new_file,$str);
		}
	}
	return $str;
}
function lx_downloadAndSaveFile($name, $ext, $tried_count=0){
	if($tried_count>2) return;
	$file = file_get_contents($name);
	if($file){
		$path = '/wp-content/uploads/'.date('Y/m').'/'.lx_randFileName($ext);
		file_put_contents(UPLOAD_IMG_PATH.$path, $file);
		//file_put_contents('/tmp/log1.txt',UPLOAD_IMG_PATH.$path);
		return $path;
	}else{
		sleep(3);
		return lx_downloadAndSaveFile($name, $ext, ++$tried_count);
	}
}
function lx_randFileName($ext){
	return date('YmdHis').floor(rand(10000,99999)).'.'.substr(trim($ext),-3);
}