本文是为大家分享php支持断点续传、分块下载的类，供大家参考，具体内容如下

/**

* User: djunny

* Date: 2016-04-29

* Time: 17:18

* Mail: 199962760@qq.com

* 支持断点下载的类

*/

class downloader {

/**

* download file to local path

*

* @param $url

* @param $save_file

* @param int $speed

* @param array $headers

* @param int $timeout

* @return bool

* @throws Exception

*/

static function get($url, $save_file, $speed = 10240, $headers = array(), $timeout = 10) {

$url_info = self::parse_url($url);

if (!$url_info['host']) {

throw new Exception('Url is Invalid');

}

// default header

$def_headers = array(

'Accept' => '*/*',

'User-Agent' => 'Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0)',

'Accept-Encoding' => 'gzip, deflate',

'Host' => $url_info['host'],

'Connection' => 'Close',

'Accept-Language' => 'zh-cn',

);

// merge heade

$headers = array_merge($def_headers, $headers);

// get content length

$content_length = self::get_content_size($url_info['host'], $url_info['port'], $url_info['request'], $headers, $timeout);

// content length not exist

if (!$content_length) {

throw new Exception('Content-Length is Not Exists');

}

// get exists length

$exists_length = is_file($save_file) ? filesize($save_file) : 0;

// get tmp data file

$data_file = $save_file . '.data';

// get tmp data

$exists_data = is_file($data_file) ? json_decode(file_get_contents($data_file), 1) : array();

// check file is valid

if ($exists_length == $content_length) {

$exists_data && @unlink($data_file);

return true;

}

// check file is expire

if ($exists_data['length'] != $content_length || $exists_length > $content_length) {

$exists_data = array(

'length' => $content_length,

);

}

// write exists data

file_put_contents($data_file, json_encode($exists_data));

try {

$download_status = self::download_content($url_info['host'], $url_info['port'], $url_info['request'], $save_file, $content_length, $exists_length, $speed, $headers, $timeout);

if ($download_status) {

@unlink($data_file);

}

} catch (Exception $e) {

throw new Exception($e->getMessage());

}

return true;

}

/**

* parse url

*

* @param $url

* @return bool|mixed

*/

static function parse_url($url) {

$url_info = parse_url($url);

if (!$url_info['host']) {

return false;

}

$url_info['port'] = $url_info['port'] ? $url_info['host'] : 80;

$url_info['request'] = $url_info['path'] . ($url_info['query'] ? '?' . $url_info['query'] : '');

return $url_info;

}

/**

* download content by chunk

*

* @param $host

* @param $port

* @param $url_path

* @param $headers

* @param $timeout

*/

static function download_content($host, $port, $url_path, $save_file, $content_length, $range_start, $speed, &$headers, $timeout) {

$request = self::build_header('GET', $url_path, $headers, $range_start);

$fsocket = @fsockopen($host, $port, $errno, $errstr, $timeout);

stream_set_blocking($fsocket, TRUE);

stream_set_timeout($fsocket, $timeout);

fwrite($fsocket, $request);

$status = stream_get_meta_data($fsocket);

if ($status['timed_out']) {

throw new Exception('Socket Connect Timeout');

}

$is_header_end = 0;

$total_size = $range_start;

$file_fp = fopen($save_file, 'a+');

while (!feof($fsocket)) {

if (!$is_header_end) {

$line = @fgets($fsocket);

if (in_array($line, array("\n", "\r\n"))) {

$is_header_end = 1;

}

continue;

}

$resp = fread($fsocket, $speed);

$read_length = strlen($resp);

if ($resp === false || $content_length < $total_size + $read_length) {

fclose($fsocket);

fclose($file_fp);

throw new Exception('Socket I/O Error Or File Was Changed');

}

$total_size += $read_length;

fputs($file_fp, $resp);

// check file end

if ($content_length == $total_size) {

break;

}

sleep(1);

// for test

//break;

}

fclose($fsocket);

fclose($file_fp);

return true;

}

/**

* get content length

*

* @param $host

* @param $port

* @param $url_path

* @param $headers

* @param $timeout

* @return int

*/

static function get_content_size($host, $port, $url_path, &$headers, $timeout) {

$request = self::build_header('HEAD', $url_path, $headers);

$fsocket = @fsockopen($host, $port, $errno, $errstr, $timeout);

stream_set_blocking($fsocket, TRUE);

stream_set_timeout($fsocket, $timeout);

fwrite($fsocket, $request);

$status = stream_get_meta_data($fsocket);

$length = 0;

if ($status['timed_out']) {

return 0;

}

while (!feof($fsocket)) {

$line = @fgets($fsocket);

if (in_array($line, array("\n", "\r\n"))) {

break;

}

$line = strtolower($line);

// get location

if (substr($line, 0, 9) == 'location:') {

$location = trim(substr($line, 9));

$url_info = self::parse_url($location);

if (!$url_info['host']) {

return 0;

}

fclose($fsocket);

return self::get_content_size($url_info['host'], $url_info['port'], $url_info['request'], $headers, $timeout);

}

// get content length

if (strpos($line, 'content-length:') !== false) {

list(, $length) = explode('content-length:', $line);

$length = (int)trim($length);

}

}

fclose($fsocket);

return $length;

}

/**

* build header for socket

*

* @param $action

* @param $url_path

* @param $headers

* @param int $range_start

* @return string

*/

static function build_header($action, $url_path, &$headers, $range_start = -1) {

$out = $action . " {$url_path} HTTP/1.0\r\n";

foreach ($headers as $hkey => $hval) {

$out .= $hkey . ': ' . $hval . "\r\n";

}

if ($range_start > -1) {

$out .= "Accept-Ranges: bytes\r\n";

$out .= "Range: bytes={$range_start}-\r\n";

}

$out .= "\r\n";

return $out;

}

}

#use age

/*

try {

if (downloader::get('http://dzs.aqtxt.com/files/11/23636/201604230358308081.rar', 'test.rar')) {

//todo

echo 'Download Succ';

}

} catch (Exception $e) {

echo 'Download Failed';

}

*/

?>

以上就是本文的全部内容，希望对大家的学习有所帮助。