header("Content-type: text/html;charset=utf-8");
if(strlen($FileName)<=3){echo "下载失败：你所以下载的文件信息有误";return;}
$FileName=iconv("utf-8","gb2312",$FileName);//进行文件名格式转换,以防中文乱码
//开始判断路径
if(!is_null($FilePath)&&strlen($FilePath)>1){

if(substr($FilePath,0,1)=='/'){//判断是否为绝对路径

$FilePath=$_SERVER['DOCUMENT_ROOT'].$FilePath;

}
if(substr($FilePath,-1)!="/"){//检查最后是否为 / 结尾

$FilePath=$FilePath.'/';

}
if(is_numeric(strpos($FilePath,":\"))){//检查是否为绝对路径

$FilePath=str_replace("/","\",$FilePath);

}
}elseif(strlen($FilePath)==1&&$FilePath!="/"){

$FilePath=$FilePath."/";

}else{

$FilePath="";

}
if(!file_exists($FilePath.$FileName)){

echo"下载失败：所要下载的文件未找到";return;

}
/*================================================
发送下载相关的头部信息
=================================================*/

header("Content-type: application/octet-stream");

header("Accept-Ranges: bytes");//按照字节大小返回

header("Accept-Length: $FileSize");//返回文件大小

header("Content-Disposition: attachment; filename=".$FileName);//这里客户端的弹出对话框，对应的文件名

/*================================================
开始下载相关
=================================================*/
$FileSize=filesize($FilePath.$FileName);

$File=fopen($FilePath.$FileName,"r");//打开文件

$FileBuff=512;

while($FileSize>=0){

$FileSize-=$FileBuff;

echo fread($File,$FileBuff);

}

fclose($File);
}
?>