Excerpted from the HTTP file download class of Dreamweaver CMS,

Extracted from the HTTP file download class of DreamWeaver CMS,

The example in this article describes the HTTP file download class taken from DreamWeaver CMS. Share it with everyone for your reference. The details are as follows:
<&#63;php if(!defined('DEDEINC')) exit("Request Error!");
/**
 * 织梦HTTP下载类
 *
 * @version  $Id: dedehttpdown.class.php 1 11:42 2010年7月6日Z tianya $
 * @package  DedeCMS.Libraries
 * @copyright  Copyright (c) 2007 - 2010, DesDev, Inc.
 * @license  http://help.dedecms.com/usersguide/license.html
 * @link   http://www.dedecms.com
 */
@set_time_limit(0);
class DedeHttpDown
{
 var $m_url = '';
 var $m_urlpath = '';
 var $m_scheme = 'http';
 var $m_host = '';
 var $m_port = '80';
 var $m_user = '';
 var $m_pass = '';
 var $m_path = '/';
 var $m_query = '';
 var $m_fp = '';
 var $m_error = '';
 var $m_httphead = '';
 var $m_html = '';
 var $m_puthead = '';
 var $BaseUrlPath = '';
 var $HomeUrl = '';
 var $reTry = 0;
 var $JumpCount = 0;
 /**
  * 初始化系统
  *
  * @access public
  * @param  string $url 需要下载的地址
  * @return string
  */
 function PrivateInit($url)
 {
  if($url=='') {
   return ;
  }
  $urls = '';
  $urls = @parse_url($url);
  $this->m_url = $url;
  if(is_array($urls))
  {
   $this->m_host = $urls["host"];
   if(!empty($urls["scheme"]))
   {
    $this->m_scheme = $urls["scheme"];
   }
   if(!empty($urls["user"]))
   {
    $this->m_user = $urls["user"];
   }
   if(!empty($urls["pass"]))
   {
    $this->m_pass = $urls["pass"];
   }
   if(!empty($urls["port"]))
   {
    $this->m_port = $urls["port"];
   }
   if(!empty($urls["path"]))
   {
    $this->m_path = $urls["path"];
   }
   $this->m_urlpath = $this->m_path;
   if(!empty($urls["query"]))
   {
    $this->m_query = $urls["query"];
    $this->m_urlpath .= "&#63;".$this->m_query;
   }
   $this->HomeUrl = $urls["host"];
   $this->BaseUrlPath = $this->HomeUrl.$urls["path"];
   $this->BaseUrlPath = preg_replace("/\/([^\/]*)\.(.*)$/","/",$this->BaseUrlPath);
   $this->BaseUrlPath = preg_replace("/\/$/","",$this->BaseUrlPath);
  }
 }
 /**
  * 重设各参数
  *
  * @access public
  * @return void
  */
 function ResetAny()
 {
  $this->m_url = "";
  $this->m_urlpath = "";
  $this->m_scheme = "http";
  $this->m_host = "";
  $this->m_port = "80";
  $this->m_user = "";
  $this->m_pass = "";
  $this->m_path = "/";
  $this->m_query = "";
  $this->m_error = "";
 }
 /**
  * 打开指定网址
  *
  * @access public
  * @param  string $url 地址
  * @param  string $requestType 请求类型
  * @return string
  */
 function OpenUrl($url,$requestType="GET")
 {
  $this->ResetAny();
  $this->JumpCount = 0;
  $this->m_httphead = Array() ;
  $this->m_html = '';
  $this->reTry = 0;
  $this->Close();
  //初始化系统
  $this->PrivateInit($url);
  $this->PrivateStartSession($requestType);
 }
 /**
  * 转到303重定向网址
  *
  * @access public
  * @param  string $url 地址
  * @return string
  */
 function JumpOpenUrl($url)
 {
  $this->ResetAny();
  $this->JumpCount++;
  $this->m_httphead = Array() ;
  $this->m_html = "";
  $this->Close();
  //初始化系统
  $this->PrivateInit($url);
  $this->PrivateStartSession('GET');
 }
 /**
  * 获得某操作错误的原因
  *
  * @access public
  * @return void
  */
 function printError()
 {
  echo "错误信息：".$this->m_error;
  echo "<br/>具体返回头：<br/>";
  foreach($this->m_httphead as $k=>$v){ echo "$k => $v <br/>\r\n"; }
 }
 /**
  * 判别用Get方法发送的头的应答结果是否正确
  *
  * @access public
  * @return bool
  */
 function IsGetOK()
 {
  if( preg_match("/^2/",$this->GetHead("http-state")) )
  {
   return TRUE;
  }
  else
  {
   $this->m_error .= $this->GetHead("http-state")." - ".$this->GetHead("http-describe")."<br/>";
   return FALSE;
  }
 }
 /**
  * 看看返回的网页是否是text类型
  *
  * @access public
  * @return bool
  */
 function IsText()
 {
  if( preg_match("/^2/",$this->GetHead("http-state")) && preg_match("/text|xml/i",$this->GetHead("content-type")) )
  {
   return TRUE;
  }
  else
  {
   $this->m_error .= "内容为非文本类型或网址重定向<br/>";
   return FALSE;
  }
 }
 /**
  * 判断返回的网页是否是特定的类型
  *
  * @access public
  * @param  string $ctype 内容类型
  * @return string
  */
 function IsContentType($ctype)
 {
  if(preg_match("/^2/",$this->GetHead("http-state"))
  && $this->GetHead("content-type")==strtolower($ctype))
  { return TRUE; }
  else
  {
   $this->m_error .= "类型不对 ".$this->GetHead("content-type")."<br/>";
   return FALSE;
  }
 }
 /**
  * 用Http协议下载文件
  *
  * @access public
  * @param  string $savefilename 保存文件名称
  * @return string
  */
 function SaveToBin($savefilename)
 {
  if(!$this->IsGetOK())
  {
   return FALSE;
  }
  if(@feof($this->m_fp))
  {
   $this->m_error = "连接已经关闭！"; return FALSE;
  }
  $fp = fopen($savefilename,"w");
  while(!feof($this->m_fp))
  {
   fwrite($fp, fread($this->m_fp, 1024));
  }
  fclose($this->m_fp);
  fclose($fp);
  return TRUE;
 }
 /**
  * 保存网页内容为Text文件
  *
  * @access public
  * @param  string $savefilename 保存文件名称
  * @return string
  */
 function SaveToText($savefilename)
 {
  if($this->IsText())
  {
   $this->SaveBinFile($savefilename);
  }
  else
  {
   return "";
  }
 }
 /**
  * 用Http协议获得一个网页的内容
  *
  * @access public
  * @return string
  */
 function GetHtml()
 {
  if(!$this->IsText())
  {
   return '';
  }
  if($this->m_html!='')
  {
   return $this->m_html;
  }
  if(!$this->m_fp||@feof($this->m_fp))
  {
   return '';
  }
  while(!feof($this->m_fp))
  {
   $this->m_html .= fgets($this->m_fp,256);
  }
  @fclose($this->m_fp);
  return $this->m_html;
 }
 /**
  * 开始HTTP会话
  *
  * @access public
  * @param  string $requestType 请求类型
  * @return string
  */
 function PrivateStartSession($requestType="GET")
 {
  if(!$this->PrivateOpenHost())
  {
   $this->m_error .= "打开远程主机出错!";
   return FALSE;
  }
  $this->reTry++;
  if($this->GetHead("http-edition")=="HTTP/1.1")
  {
   $httpv = "HTTP/1.1";
  }
  else
  {
   $httpv = "HTTP/1.0";
  }
  $ps = explode('&#63;',$this->m_urlpath);
  $headString = '';
  //发送固定的起始请求头GET、Host信息
  if($requestType=="GET")
  {
   $headString .= "GET ".$this->m_urlpath." $httpv\r\n";
  }
  else
  {
   $headString .= "POST ".$ps[0]." $httpv\r\n";
  }
  $this->m_puthead["Host"] = $this->m_host;
  //发送用户自定义的请求头
  if(!isset($this->m_puthead["Accept"]))
  {
   $this->m_puthead["Accept"] = "*/*";
  }
  if(!isset($this->m_puthead["User-Agent"]))
  {
   $this->m_puthead["User-Agent"] = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2)";
  }
  if(!isset($this->m_puthead["Refer"]))
  {
   $this->m_puthead["Refer"] = "http://".$this->m_puthead["Host"];
  }
  foreach($this->m_puthead as $k=>$v)
  {
   $k = trim($k);
   $v = trim($v);
   if($k!=""&&$v!="")
   {
    $headString .= "$k: $v\r\n";
   }
  }
  fputs($this->m_fp, $headString);
  if($requestType=="POST")
  {
   $postdata = "";
   if(count($ps)>1)
   {
    for($i=1;$i<count($ps);$i++)
    {
     $postdata .= $ps[$i];
    }
   }
   else
   {
    $postdata = "OK";
   }
   $plen = strlen($postdata);
   fputs($this->m_fp,"Content-Type: application/x-www-form-urlencoded\r\n");
   fputs($this->m_fp,"Content-Length: $plen\r\n");
  }
  //发送固定的结束请求头
  //HTTP1.1协议必须指定文档结束后关闭链接,否则读取文档时无法使用feof判断结束
  if($httpv=="HTTP/1.1")
  {
   fputs($this->m_fp,"Connection: Close\r\n\r\n");
  }
  else
  {
   fputs($this->m_fp,"\r\n");
  }
  if($requestType=="POST")
  {
   fputs($this->m_fp,$postdata);
  }
  //获取应答头状态信息
  $httpstas = explode(" ",fgets($this->m_fp,256));
  $this->m_httphead["http-edition"] = trim($httpstas[0]);
  $this->m_httphead["http-state"] = trim($httpstas[1]);
  $this->m_httphead["http-describe"] = "";
  for($i=2;$i<count($httpstas);$i++)
  {
   $this->m_httphead["http-describe"] .= " ".trim($httpstas[$i]);
  }
  //获取详细应答头
  while(!feof($this->m_fp))
  {
   $line = trim(fgets($this->m_fp,256));
   if($line == "")
   {
    break;
   }
   $hkey = "";
   $hvalue = "";
   $v = 0;
   for($i=0;$i<strlen($line);$i++)
   {
    if($v==1)
    {
     $hvalue .= $line[$i];
    }
    if($line[$i]==":")
    {
     $v = 1;
    }
    if($v==0)
    {
     $hkey .= $line[$i];
    }
   }
   $hkey = trim($hkey);
   if($hkey!="")
   {
    $this->m_httphead[strtolower($hkey)] = trim($hvalue);
   }
  }
  //如果连接被不正常关闭，重试
  if(feof($this->m_fp))
  {
   if($this->reTry > 10)
   {
    return FALSE;
   }
   $this->PrivateStartSession($requestType);
  }
  //判断是否是3xx开头的应答
  if(preg_match("/^3/",$this->m_httphead["http-state"]))
  {
   if($this->JumpCount > 3)
   {
    return;
   }
   if(isset($this->m_httphead["location"]))
   {
    $newurl = $this->m_httphead["location"];
    if(preg_match("/^http/i",$newurl))
    {
     $this->JumpOpenUrl($newurl);
    }
    else
    {
     $newurl = $this->FillUrl($newurl);
     $this->JumpOpenUrl($newurl);
    }
   }
   else
   {
    $this->m_error = "无法识别的答复！";
   }
  }
 }
 /**
  * 获得一个Http头的值
  *
  * @access public
  * @param  string $headname 头文件名称
  * @return string
  */
 function GetHead($headname)
 {
  $headname = strtolower($headname);
  return isset($this->m_httphead[$headname]) &#63; $this->m_httphead[$headname] : '';
 }
 /**
  * 设置Http头的值
  *
  * @access public
  * @param  string $skey 键
  * @param  string $svalue 值
  * @return string
  */
 function SetHead($skey,$svalue)
 {
  $this->m_puthead[$skey] = $svalue;
 }
 /**
  * 打开连接
  *
  * @access public
  * @return bool
  */
 function PrivateOpenHost()
 {
  if($this->m_host=="")
  {
   return FALSE;
  }
  $errno = "";
  $errstr = "";
  $this->m_fp = @fsockopen($this->m_host, $this->m_port, $errno, $errstr,10);
  if(!$this->m_fp)
  {
   $this->m_error = $errstr;
   return FALSE;
  }
  else
  {
   return TRUE;
  }
 }
 /**
  * 关闭连接
  *
  * @access public
  * @return void
  */
 function Close()
 {
  @fclose($this->m_fp);
 }
 /**
  * 补全相对网址
  *
  * @access public
  * @param  string $surl 需要不全的地址
  * @return string
  */
 function FillUrl($surl)
 {
  $i = 0;
  $dstr = "";
  $pstr = "";
  $okurl = "";
  $pathStep = 0;
  $surl = trim($surl);
  if($surl=="")
  {
   return "";
  }
  $pos = strpos($surl,"#");
  if($pos>0)
  {
   $surl = substr($surl,0,$pos);
  }
  if($surl[0]=="/")
  {
   $okurl = "http://".$this->HomeUrl.$surl;
  }
  else if($surl[0]==".")
  {
   if(strlen($surl)<=1)
   {
    return "";
   }
   else if($surl[1]=="/")
   {
    $okurl = "http://".$this->BaseUrlPath."/".substr($surl,2,strlen($surl)-2);
   }
   else
   {
    $urls = explode("/",$surl);
    foreach($urls as $u)
    {
     if($u=="..")
     {
      $pathStep++;
     }
     else if($i<count($urls)-1)
     {
      $dstr .= $urls[$i]."/";
     }
     else
     {
      $dstr .= $urls[$i];
     }
     $i++;
    }
    $urls = explode("/",$this->BaseUrlPath);
    if(count($urls) <= $pathStep)
    {
     return "";
    }
    else
    {
     $pstr = "http://";
     for($i=0;$i<count($urls)-$pathStep;$i++)
     {
      $pstr .= $urls[$i]."/";
     }
     $okurl = $pstr.$dstr;
    }
   }
  }
  else
  {
   if(strlen($surl)<7)
   {
    $okurl = "http://".$this->BaseUrlPath."/".$surl;
   }
   else if(strtolower(substr($surl,0,7))=="http://")
   {
    $okurl = $surl;
   }
   else
   {
    $okurl = "http://".$this->BaseUrlPath."/".$surl;
   }
  }
  $okurl = preg_replace("/^(http:\/\/)/i","",$okurl);
  $okurl = preg_replace("/\/{1,}/", "/", $okurl);
  return "http://".$okurl;
 }
}//End Class
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