PHP实现文件下载限速功能的方法详解

/**
 * 下载文件并限速
 *
 * @param string $file_path 文件路径
 * @param int $kilobytes 每秒下载的 KB 数
 */
function downloadFileWithSpeedLimit($file_path, $kilobytes = 100) {
    if (file_exists($file_path)) {
        // 获取文件大小
        $file_size = filesize($file_path);
 
        // 设置下载响应头
        header('Content-Description: File Transfer');
        header('Content-Type: application/octet-stream');
        header('Content-Disposition: attachment; filename=' . basename($file_path));
        header('Content-Transfer-Encoding: binary');
        header('Expires: 0');
        header('Cache-Control: must-revalidate');
        header('Pragma: public');
        header('Content-Length: ' . $file_size);
 
        // 打开文件并进行读取
        $file = fopen($file_path, "rb");
 
        // 设置下载速度限制
        $limit_speed = $kilobytes * 1024; // 转换为字节
        $start_time = microtime(true);
        while (!feof($file)) {
            echo fread($file, $limit_speed);
            flush();
            usleep(1000000 / $limit_speed);
            $elapsed_time = microtime(true) - $start_time;
            if ($elapsed_time > 1) {
                $start_time = microtime(true);
            }
        }
 
        // 关闭文件句柄
        fclose($file);
        exit;
    } else {
        echo "文件不存在！";
    }
}
 
// 调用方法，下载文件并限速
$file_path = "your_file_path"; // 替换为要下载的文件路径
downloadFileWithSpeedLimit($file_path, 100); // 设置下载速率为每秒 100KB

<?php
//设置文件最长执行时间
set_time_limit(0);
if (isset($_GET['filename']) && !empty($_GET['filename'])) {
  $file_name = $_GET['filename'];
  $file = __DIR__ . '/assets/' . $file_name;
} else {
  echo 'what are your searching for?';
  exit();
}
if (file_exists($file) && is_file($file)) {
  $filesize = filesize($file);
  header('Content-Description: File Transfer');
  header('Content-Type: application/octet-stream');
  header('Content-Transfer-Encoding: binary');
  header('Accept-Ranges: bytes');
  header('Expires: 0');
  header('Cache-Control: must-revalidate');
  header('Pragma: public');
  header('Content-Length: ' . $filesize);
  header('Content-Disposition: attachment; filename=' . $file_name);
  // 打开文件
  $fp = fopen($file, 'rb');
  // 设置指针位置
  fseek($fp, 0);
  // 开启缓冲区
  ob_start();
  // 分段读取文件
  while (!feof($fp)) {
    $chunk_size = 1024 * 1024 * 2; // 2MB
    echo fread($fp, $chunk_size);
    ob_flush(); // 刷新PHP缓冲区到Web服务器    flush(); // 刷新Web服务器缓冲区到浏览器
    sleep(1); // 每1秒 下载 2 MB
  }
  // 关闭缓冲区
  ob_end_clean();
  fclose($fp);
} else {
  echo 'file not exists or has been removed!';
}
exit();

<?php
 /*
 * set here a limit of downloading rate (e.g. 10.20 Kb/s)
 */
 $download_rate = 10.20;
 $download_file = 'download-file.zip';
 $target_file = 'target-file.zip';
 if(file_exists($download_file)){
  /* headers */
  header('Last-Modified:'.gmdate('D, d M Y H:i:s').'GMT');
  header('Cache-control: private');
  header('Content-Type: application/octet-stream');
  header('Content-Length: '.filesize($download_file));
  header('Content-Disposition: filename='.$target_file);
  /* flush content */
  flush();
  /* open file */
  $fh = @fopen($download_file, 'r');
  while(!feof($fh)){
   /* send only current part of the file to browser */
   print fread($fh, round($download_rate * 1024));
   /* flush the content to the browser */
   flush();
   /* sleep for 1 sec */
   sleep(1);
  }
  /* close file */
  @fclose($fh);
 }else{
  die('Fatal error: the '.$download_file.' file does not exist!');
 }
?>

// local file that should be send to the client
$local_file = 'test-file.zip';
// filename that the user gets as default
$download_file = 'your-download-name.zip';
// set the download rate limit (=> 20,5 kb/s)
$download_rate = 20.5;
if(file_exists($local_file) && is_file($local_file)) {
 // send headers
 header('Cache-control: private');
 header('Content-Type: application/octet-stream');
 header('Content-Length: '.filesize($local_file));
 header('Content-Disposition: filename='.$download_file);
 // flush content
 flush();
 // open file stream
 $file = fopen($local_file, "r");
 while (!feof($file)) {
 // send the current file part to the browser
 print fread($file, round($download_rate * 1024));
 // flush the content to the browser
 flush();
 // sleep one second
 sleep(1);
 }
 // close file stream
 fclose($file);
}
else {
 die('Error: The file '.$local_file.' does not exist!');
}