php图片下载详解编程语言

function iDownload(){ 
 
        $name=$_GET['name']; //获取图片地址$file = fopen($dir,"r"); // 打开文件    
        $dir='/www/image/';$ext=strrchr($name,".");  
         
        if($ext!=".gif" && $ext!=".jpg" && $ext!=".png")  
            return false;  
 
        $file_path=$dir.$name; 
        $size=filesize($file_path); 
        $file = fopen($file_path,"r") or die("file is not exist");; // 打开文件   
         
        Header("Content-type: application/octet-stream");  
        Header("Accept-Ranges: bytes");  
        Header("Accept-Length: ".$size);  
        Header("Content-Disposition: attachment; filename=" . $name);  
        echo fread($file,$size);  
        fclose($file);  
        exit;  
    }