php 根据URL下载远程图片、压缩包、pdf等文件到本

//远程路径，名称，文件后缀
function downImgRar($url,$rename,$ext){
  switch ($ext) {
    case 'jpg':    //下载图片
      $file_path = 'uploads/images/';      
      break;
    case 'png':    //下载图片
      $file_path = 'uploads/images/';      
      break;
    case 'pdf':    //下载PDF
      $file_path = 'uploads/pdf/';  
      break;
    case 'rar':    //下载压缩包
      $file_path = 'uploads/rar/';      
      break;
    case 'zip':    //下载压缩包
      $file_path = 'uploads/rar/';      
      break;
    default:
      $file_path = 'uploads/files/';      
    break;
  }
  $ch = curl_init($url);
  curl_setopt($ch, CURLOPT_HEADER, 0);
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
  curl_setopt($ch, CURLOPT_BINARYTRANSFER,1);
  $rawdata=curl_exec ($ch);
  curl_close ($ch);
  // 使用中文文件名需要转码
  $fp = fopen($file_path.iconv('UTF-8', 'GBK', $rename).".".$ext,'w');
  fwrite($fp, $rawdata);
  fclose($fp);
  // 返回路径
  return $_SERVER['DOCUMENT_ROOT'].$file_path.$rename.".".$ext;
}

// 下载压缩包
function downRar($file_path)
{
  $file_name = '/uploads/rar/2009323162920-维C银翘片说明书.rar';
  $file_name = iconv("utf-8","gbk//IGNORE",$file_name); // 特别注意！特别注意！特别注意这里，windows下必须开转码,不然直接文件不存
  $file_path = $_SERVER['DOCUMENT_ROOT'] . $file_name;// 比如windows下这里我的是 "D:/web/public/uploads/rar/2009323162920-维C银翘片说明书.rar"
  //判断如果文件存在,则跳转到下载路径
  if (!file_exists($file_path)) {
    die("文件不存在!");
  }
  $fp = fopen($file_path, "r+") or die('打开文件错误');  //下载文件必须要将文件先打开。写入内存
  $file_size = filesize($file_path);
  //返回的文件流
  Header("Content-type:application/octet-stream");
  //按照字节格式返回
  Header("Accept-Ranges:bytes");
  //返回文件大小
  Header("Accept-Length:" . $file_size);
  //弹出客户端对话框，对应的文件名
  Header("Content-Disposition:attachment;filename=" . substr($file_name, strrpos($file_name, '/') + 1));
  //防止服务器瞬间压力增大，分段读取
  $buffer = 1024;
  while (!feof($fp)) {
    $file_data = fread($fp, $buffer);
    echo $file_data;
  }
  fclose($fp);
  die("下载成功!");
}