// 初始化一个 curl
$ch = curl_init();
// 设置请求的 url
curl_setopt($ch, CURLOPT_URL, $url);
// 
curl_setopt($ch, CURLOPT_HEADER, 0);
// 不直接输出，而是通过 curl_exec 返回
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
if (false === ($stream = curl_exec($ch))) {
 throw new \Exception(curl_errno($ch));
}
curl_close($ch);
return $stream;

class Request
{
 protected $bar;
 // 是否下载完成
 protected $downloaded = false;
 public function __construct()
 {
 // 初始化一个进度条
 $this->bar = new CliProgressBar(100);
 $this->bar->display();
 $this->bar->setColorToRed();
 }
 
 function download($url)
 {
 $ch = curl_init();
 // 从配置文件中获取根路径
 curl_setopt($ch, CURLOPT_URL, $url);
 curl_setopt($ch, CURLOPT_RETURNTRANSFER, 0);
 // 开启进度条
 curl_setopt($ch, CURLOPT_NOPROGRESS, 0);
 // 进度条的触发函数
 curl_setopt($ch, CURLOPT_PROGRESSFUNCTION, 'progress');
 // ps: 如果目标网页跳转，也跟着跳转
 // curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
 if (false === ($stream = curl_exec($ch))) {
  throw new \Exception(curl_errno($ch));
 }
 curl_close($ch);
 return $stream;
 }
 
 /**
 * 进度条下载.
 *
 * @param $ch
 * @param $countDownloadSize 总下载量
 * @param $currentDownloadSize 当前下载量
 * @param $countUploadSize 
 * @param $currentUploadSize
 */
 public function progress($ch, $countDownloadSize, $currentDownloadSize, $countUploadSize, $currentUploadSize)
 {
  // 等于 0 的时候，应该是预读资源不等于0的时候即开始下载
  // 这里的每一个判断都是坑，多试试就知道了
 if (0 === $countDownloadSize) {
  return false;
 }
 // 有时候会下载两次，第一次很小，应该是重定向下载
 if ($countDownloadSize > $currentDownloadSize) {
  $this->downloaded = false;
  // 继续显示进度条
 }
 // 已经下载完成还会再发三次请求
 elseif ($this->downloaded) {
  return false;
 }
 // 两边相等下载完成并不一定结束，
 elseif ($currentDownloadSize === $countDownloadSize) {
  return false;
 }
 
 // 开始计算
 $bar = $currentDownloadSize / $countDownloadSize * 100;
 $this->bar->progress($bar);
 }
}
(new Request)->download('http://www.shiguopeng.cn/database.sql');