\extendDownLoad

<?php
// +----------------------------------------------------------------------
// | Project: 晴玖商城
// +----------------------------------------------------------------------
// | Creation: 2022/1/10 15:14
// +----------------------------------------------------------------------
// | Filename: DownLoad.php
// +----------------------------------------------------------------------
// | Explain: 下载操作集成，支持分块下载
// +----------------------------------------------------------------------
namespace extend;

use Exception;

class DownLoad
{
    /**
     * 远程文件的路径
     * @var string
     */
    private $siteUrl = '';

    /**
     * Http请求头
     * @var array
     */
    private $header = [];

    /**
     * 分片下载大小
     * @var int
     */
    private $burstBytes = 1048576;

    /**
     * 设置远程下载文件的路径
     * @param string $url 远程文件的路径
     * @return $this
     */
    public function setUrl($url)
    {
        $this->siteUrl = $url;
        return $this;
    }

    /**
     * 设置分段下载字节大小
     * @param int $byte 字节大小
     * @return $this
     */
    public function setBurst($byte)
    {
        $this->burstBytes = $byte;
        return $this;
    }

    /**
     * 设置Http请求头
     * @param array $header 请求头
     * @return $this
     */
    public function setHeader($header)
    {
        $this->header = $header;
        return $this;
    }

    /**
     * 获取远程文件的信息
     * @return array
     * @throws Exception
     */
    private function getSiteFiLeInfo()
    {
        if (!$this->siteUrl) {
            throw new Exception('请先设置远程文件url!');
        }
        $responseHeader = get_headers($this->siteUrl, 1);
        if (!$responseHeader) {
            throw new Exception('获取远程文件信息失败!');
        }
        if (!empty($responseHeader['Location'])) {
            //处理文件下载302问题
            $this->siteUrl = $responseHeader['Location'];
            return $this->getSiteFiLeInfo();
        }

        return $responseHeader;
    }

    /**
     * 保存文件到本地
     * @param string $fileName 保存到本地的文件名称
     * @throws
     */
    public function saveFile($fileName)
    {
        //获取远程文件的信息
        $siteFileInfo = $this->getSiteFiLeInfo();
        $siteFileLength = $siteFileInfo['Content-Length'] ?? 0;

        //根据文件是否存在创建文件句柄
        if (file_exists($fileName)) {
            $fd = fopen($fileName, 'ab');
        } else {
            $fd = fopen($fileName, 'wb');
        }
        if (!$fd) {
            throw new Exception('创建或打开本地文件失败!');
        }

        //加上文件锁,防止刷新抢占资源句柄
        if (!flock($fd, LOCK_EX | LOCK_NB)) {
            throw new Exception('已有相关进程操作执行下载本文件!');
        }

        //检查文件是否已经下载完成
        $fileSize = filesize($fileName);
        if ($fileSize && $fileSize >= $siteFileLength) {
            //throw new Exception('原文件已下载完成,请勿重复下载!');
        }

        //计算断点下载开始和结束字节
        $sByte = $fileSize;
        $eByte = $sByte + $this->burstBytes;

        //循环下载文件
        while (true) {
            //文件下载完成
            if ($fileSize >= $siteFileLength) {
                fclose($fd);
                break;
            }

            //传递分片范围
            $xRange = "{$sByte}-{$eByte}";

            //请求curl
            $result = $this->curl($xRange);

            //检查是否正常请求
            $code = $result['code'] ?? 0;
            if (!$code) {
                throw new Exception('Http请求异常!');
            }
            if ($code != 206) {
                throw new Exception('Http状态码异常,可能不支持断点的资源或已完成下载!');
            }

            //返回流长度
            $streamLength = $result['length'] ?? 0;

            //返回流内容
            $streamContent = $result['stream'] ?? '';
            if ($streamLength > 0) {
                $saveRes = fwrite($fd, $streamContent);
                if (!$saveRes) {
                    throw new Exception('写入流到文件失败!');
                }
                if ($saveRes != $streamLength) {
                    //讲道理这种情况基本不会遇到,除非分段数设置过大,暂时未做兼容处理,重新执行就行
                    throw new Exception('数据异常:返回大小和写入大小不一致!');
                }

                //递增range
                $sByte = $eByte + 1;
                $eByte = $sByte + $this->burstBytes;

                //记录文件大小
                $fileSize = $fileSize + $saveRes;
            }
        }
    }

    /**
     * 获取下载文件流
     * @param string $range 分片字节范围
     * @return array
     * @throws
     */
    private function curl($range)
    {
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, $this->siteUrl);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'GET');
        curl_setopt($ch, CURLOPT_HEADER, TRUE);

        //设置关闭SSL
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 0);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);

        //设置分片
        curl_setopt($ch, CURLOPT_RANGE, $range);

        //设置header
        if ($this->header) {
            curl_setopt($ch, CURLOPT_HTTPHEADER, $this->header);
        }

        //执行请求
        $response = curl_exec($ch);
        if (curl_errno($ch)) {
            throw new Exception('下载文件异常:' . curl_error($ch));
        }

        //提取response_header和response_body
        $headSize = curl_getinfo($ch, CURLINFO_HEADER_SIZE);
        $httpHeader = substr($response, 0, $headSize);
        if (!$httpHeader) {
            throw new Exception('下载文件异常:未获取到响应头');
        }
        $fileStream = substr($response, $headSize);

        //解析header
        $length = $this->getResHeaderValue('Content-Length', $httpHeader);
        $httpCode = $this->getResHeaderValue('Http-Code', $httpHeader);
        curl_close($ch);

        //返回
        return [
            'code' => $httpCode,
            'length' => $length,
            'stream' => $fileStream,
        ];
    }

    /**
     * 获取响应头某个Key的值
     * @param string $key header头的key
     * @param string $responseHead header头字符串
     * @return string
     */
    private function getResHeaderValue($key, $responseHead)
    {
        $value = '';
        $headArr = explode("\r\n", $responseHead);
        foreach ($headArr as $loop) {
            if ($key == 'Http-Code') {
                if (preg_match('/HTTP\/1\.[0-9]{1} ([0-9]{3})/', $loop, $matches)) {
                    return $matches['1'];
                }
            } else {
                if (strpos($loop, $key) !== false) {
                    $value = trim(str_replace($key . ':', '', $loop));
                }
            }
        }

        return $value;
    }
}