PHP grabs the images in the content and downloads the saved code

<?php
 //$url 远程完整图片地址，不能为空
 //程序员之家 http://bbs.it-home.org
 //$filename 另存为的图片名称，保存在与脚本相同的目录中
 function getImage($url, $filename=""){
  if($url == ""){return false;}
  $ext = strrchr($url, ".");//获取图片的扩展名
  if($ext != ".gif" && $ext != ".jpg" && $ext != ".bmp"){
   echo "格式不支持！";return false;
  }
  if($filename == ""){
   $filename = time()."$ext";
  }
  ob_start();
  readfile($url);
  $img = ob_get_contents();
  ob_end_clean();
  $size = strlen($img);
  $fp2 = fopen($filename , "a");           
  fwrite($fp2, $img);
  fclose($fp2);
  return $filename;
 }
 //测试
 getImage("http://bbs.it-home.org/images/123.jpg", "zq123.jpg");
?>