<?php
/**
* 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;
}
}
?>
