简易使用方法: 
复制代码 代码如下:
$object = new httpdownload();
$object->set_byfile($file)%n#h#%;//服务器文件名,包括路径
$object->filename = $filename;//下载另存为的文件名
$object->download();
3.源文件:
复制代码 代码如下:
class httpdownload {
var $data = null;
var $data_len = 0;
var $data_mod = 0;
var $data_type = 0;
var $data_section = 0; //section download
var $sentsize=0;
var $handler = array('auth' => null);
var $use_resume = true;
var $use_autoexit = false;
var $use_auth = false;
var $filename = null;
var $mime = null;
var $bufsize = 2048;
var $seek_start = 0;
var $seek_end = -1;
var $totalsizeref = 0;
var $bandwidth = 0;
var $speed = 0;
function initialize() {
global $http_server_vars;
if ($this->use_auth) //use authentication
{
if (!$this->_auth()) //no authentication
{
header('www-authenticate: basic realm=please enter your username and password');
header('http/1.0 401 unauthorized');
header('status: 401 unauthorized');
if ($this->use_autoexit) exit();
return false;
}
}
if ($this->mime == null) $this->mime = application/octet-stream; //default mime
if (isset($_server['http_range']) || isset($http_server_vars['http_range']))
{
if (isset($http_server_vars['http_range'])) $seek_range = substr($http_server_vars['http_range'] , strlen('bytes='));
else $seek_range = substr($_server['http_range'] , strlen('bytes='));
$range = explode('-',$seek_range);
if ($range[0] > 0)
{
$this->seek_start = intval($range[0]);
}
if ($range[1] > 0) $this->seek_end = intval($range[1]);
else $this->seek_end = -1;
if (!$this->use_resume)
{
$this->seek_start = 0;
//header(http/1.0 404 bad request);
//header(status: 400 bad request);
//exit;
//return false;
}
else
{
$this->data_section = 1;
}
}
else
{
$this->seek_start = 0;
$this->seek_end = -1;
}
$this->sentsize=0;
return true;
}
function header($size,$seek_start=null,$seek_end=null) {
header('content-type: ' . $this->mime);
header('content-disposition: attachment; filename=' . $this->filename . '');
header('last-modified: ' . date('d, d m y h:i:s \g\m\t' , $this->data_mod));
if ($this->data_section && $this->use_resume)
{
header(http/1.0 206 partial content);
header(status: 206 partial content);
header('accept-ranges: bytes');
header(content-range: bytes $seek_start-$seek_end/$size);
header(content-length: . ($seek_end - $seek_start + 1));
}
else
{
header(content-length: $size);
}
}
function download_ex($size)
{
if (!$this->initialize()) return false;
ignore_user_abort(true);
//use seek end here
if ($this->seek_start > ($size - 1)) $this->seek_start = 0;
if ($this->seek_end seek_end = $size - 1;
$this->header($size,$seek,$this->seek_end);
$this->data_mod = time();
return true;
}
function download() {
if (!$this->initialize()) return false;
try
{
error_log(begin download\n, 3,/usr/local/www/apache22/logs/apache22_php.err);
$seek = $this->seek_start;
$speed = $this->speed;
$bufsize = $this->bufsize;
$packet = 1;
//do some clean up
@ob_end_clean();
$old_status = ignore_user_abort(true);
@set_time_limit(0);
$this->bandwidth = 0;
$size = $this->data_len;
if ($this->data_type == 0) //download from a file
{
$size = filesize($this->data);
if ($seek > ($size - 1)) $seek = 0;
if ($this->filename == null) $this->filename = basename($this->data);
$res = fopen($this->data,'rb');
if ($seek) fseek($res , $seek);
if ($this->seek_end seek_end = $size - 1;
$this->header($size,$seek,$this->seek_end); //always use the last seek
$size = $this->seek_end - $seek + 1;
while (!(connection_aborted() || connection_status() == 1) && $size > 0)
{
if ($size {
echo fread($res , $size);
$this->bandwidth += $size;
$this->sentsize+=$size;
}
else
{
echo fread($res , $bufsize);
$this->bandwidth += $bufsize;
$this->sentsize+=$bufsize;
}
$size -= $bufsize;
flush();
if ($speed > 0 && ($this->bandwidth > $speed*$packet*1024))
{
sleep(1);
$packet++;
}
}
fclose($res);
}
elseif ($this->data_type == 1) //download from a string
{
if ($seek > ($size - 1)) $seek = 0;
if ($this->seek_end seek_end = $this->data_len - 1;
$this->data = substr($this->data , $seek , $this->seek_end - $seek + 1);
if ($this->filename == null) $this->filename = time();
$size = strlen($this->data);
$this->header($this->data_len,$seek,$this->seek_end);
while (!connection_aborted() && $size > 0) {
if ($size {
$this->bandwidth += $size;
$this->sentsize+=$size;
}
else
{
$this->bandwidth += $bufsize;
$this->sentsize+=$bufsize;
}
echo substr($this->data , 0 , $bufsize);
$this->data = substr($this->data , $bufsize);
$size -= $bufsize;
flush();
if ($speed > 0 && ($this->bandwidth > $speed*$packet*1024))
{
sleep(1);
$packet++;
}
}
} else if ($this->data_type == 2) {
//just send a redirect header
header('location: ' . $this->data);
}
if($this->totalsizeref==$this->sentsize )error_log(end download\n, 3,/usr/local/www/apache22/logs/apache22_php.err);
else error_log(download is canceled\n, 3,/usr/local/www/apache22/logs/apache22_php.err);
if ($this->use_autoexit) exit();
//restore old status
ignore_user_abort($old_status);
set_time_limit(ini_get(max_execution_time));
}
catch(exception $e)
{
error_log(cancel download\n.$e, 3,/usr/local/www/apache22/logs/apache22_php.err);
}
return true;
}
function set_byfile($dir) {
if (is_readable($dir) && is_file($dir)) {
$this->data_len = 0;
$this->data = $dir;
$this->data_type = 0;
$this->data_mod = filemtime($dir);
$this->totalsizeref = filesize($dir);
return true;
} else return false;
}
function set_bydata($data) {
if ($data == '') return false;
$this->data = $data;
$this->data_len = strlen($data);
$this->data_type = 1;
$this->data_mod = time();
return true;
}
function set_byurl($data) {
$this->data = $data;
$this->data_len = 0;
$this->data_type = 2;
return true;
}
function set_lastmodtime($time) {
$time = intval($time);
if ($time $this->data_mod = $time;
}
function _auth() {
if (!isset($_server['php_auth_user'])) return false;
if (isset($this->handler['auth']) && function_exists($this->handler['auth']))
{
return $this->handler['auth']('auth' , $_server['php_auth_user'],$_server['php_auth_pw']);
}
else return true; //you must use a handler
}
}
?>