1 class FileDownload{ // class start
2
3 private $_speed = 512; // 下载速度
4
5 /** 下载
6 * @param String $file 要下载的文件路径
7 * @param String $name 文件名称,为空则与下载的文件名称一样
8 * @param boolean $reload 是否开启断点续传
9 */
10 public function download($file, $name='', $reload=false){
11 if(file_exists($file)){
12 if($name==''){
13 $name = basename($file);
14 }
15
16 $fp = fopen($file, 'rb');
17 $file_size = filesize($file);
18 $ranges = $this->getRange($file_size);
19
20 header('cache-control:public');
21 header('content-type:application/octet-stream');
22 header('content-disposition:attachment; filename='.$name);
23
24 if($reload && $ranges!=null){ // 使用续传
25 header('HTTP/1.1 206 Partial Content');
26 header('Accept-Ranges:bytes');
27
28 // 剩余长度
29 header(sprintf('content-length:%u',$ranges['end']-$ranges['start']));
30
31 // range信息
32 header(sprintf('content-range:bytes %s-%s/%s', $ranges['start'], $ranges['end'], $file_size));
33
34 // fp指针跳到断点位置
35 fseek($fp, sprintf('%u', $ranges['start']));
36 }else{
37 header('HTTP/1.1 200 OK');
38 header('content-length:'.$file_size);
39 }
40
41 while(!feof($fp)){
42 echo fread($fp, round($this->_speed*1024,0));
43 ob_flush();
44 //sleep(1); // 用于测试,减慢下载速度
45 }
46
47 ($fp!=null) && fclose($fp);
48
49 }else{
50 return '';
51 }
52 }
53
54 /** 设置下载速度
55 * @param int $speed
56 */
57 public function setSpeed($speed){
58 if(is_numeric($speed) && $speed>16 && $speed<4096){
59 $this->_speed = $speed;
60 }
61 }
62
63 /** 获取header range信息
64 * @param int $file_size 文件大小
65 * @return Array
66 */
67 private function getRange($file_size){
68 if(isset($_SERVER['HTTP_RANGE']) && !empty($_SERVER['HTTP_RANGE'])){
69 $range = $_SERVER['HTTP_RANGE'];
70 $range = preg_replace('/[\s|,].*/', '', $range);
71 $range = explode('-', substr($range, 6));
72 if(count($range)<2){
73 $range[1] = $file_size;
74 }
75 $range = array_combine(array('start','end'), $range);
76 if(empty($range['start'])){
77 $range['start'] = 0;
78 }
79 if(empty($range['end'])){
80 $range['end'] = $file_size;
81 }
82 return $range;
83 }
84 return null;
85 }
86 }
