• 初始化
  */
  public function PrivateInit($url){
  $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"];
  $this->m_urlpath .= "?".$this->m_query;
  }
  }
  }

/**

• 打开指定网址
  */
  function OpenUrl($url) {

  重设各参数

  $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 = "";
  $this->m_httphead = "" ;
  $this->m_html = "";
  $this->Close();

  初始化系统

  $this->PrivateInit($url);
  $this->PrivateStartSession();
  }

/**

• 获得某操作错误的原因
  */
  public function printError() {
  echo "错误信息：".$this->m_error;
  echo "具体返回头：
  ";
  foreach($this->m_httphead as $k=>$v) {
  echo "$k => $v
  \r\n";
  }
  }

/**

• 判别用Get方法发送的头的应答结果是否正确
  */
  public function IsGetOK() {
  if( ereg("^2",$this->GetHead("http-state")) ) {
  return true;
  } else {
  $this->m_error .= $this->GetHead("http-state")." - ".$this->GetHead("http-describe")."
  ";
  return false;
  }
  }

/**

• 看看返回的网页是否是text类型
  */
  public function IsText() {
  if (ereg("^2",$this->GetHead("http-state")) && eregi("^text",$this->GetHead("content-type"))) {
  return true;
  } else {
  $this->m_error .= "内容为非文本类型
  ";
  return false;
  }
  }
  /**
• 判断返回的网页是否是特定的类型
  */
  public function IsContentType($ctype) {
  if (ereg("^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")."
  ";
  return false;
  }
  }

/**

• 用 HTTP 协议下载文件
  */
  public 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") or die("写入文件 $savefilename 失败！");
  while (!feof($this->m_fp)) {
  @fwrite($fp,fgets($this->m_fp,256));
  }
  @fclose($this->m_fp);
  return true;
  }

/**

• 保存网页内容为 Text 文件
  */
  public function SaveToText($savefilename) {
  if ($this->IsText()) {
  $this->SaveBinFile($savefilename);
  } else {
  return "";
  }
  }

/**

• 用 HTTP 协议获得一个网页的内容
  */
  public 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
  /
  public function PrivateStartSession() {
  if (!$this->PrivateOpenHost()) {
  $this->m_error .= "打开远程主机出错!";
  return false;
  }
  if ($this->GetHead("http-edition")=="HTTP/1.1") {
  $httpv = "HTTP/1.1";
  } else {
  $httpv = "HTTP/1.0";
  }
  fputs($this->m_fp,"GET ".$this->m_urlpath." $httpv\r\n");
  fputs($this->m_fp,"Host: ".$this->m_host."\r\n");
  fputs($this->m_fp,"Accept: /*\r\n");
  fputs($this->m_fp,"User-Agent: Mozilla/4.0+(compatible;+MSIE+6.0;+Windows+NT+5.2)\r\n");

  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");
  }
  $httpstas = fgets($this->m_fp,256);
  $httpstas = split(" ",$httpstas);
  $this->m_httphead["http-edition"] = trim($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[$i]);
  }
  while (!feof($this->m_fp)) {
  $line = str_replace("\"","",trim(fgets($this->m_fp,256)));
  if($line == "") break;
  if (ereg(":",$line)) {
  $lines = split(":",$line);
  $this->m_httphead[strtolower(trim($lines[0]))] = trim($lines[1]);
  }
  }
  }

/**

• 获得一个Http头的值
  */
  public function GetHead($headname) {
  $headname = strtolower($headname);
  if (isset($this->m_httphead[$headname])) {
  return $this->m_httphead[$headname];
  } else {
  return "";
  }
  }

/**

• 打开连接
  */
  public function PrivateOpenHost() {
  if ($this->m_host=="") return false;
  $this->m_fp = @fsockopen($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
  */
  public function Close(){
  @fclose($this->m_fp);
  }
  }

两种使用方法，分别如下：

打开网页

$httpdown = new HttpDownload();
$httpdown->OpenUrl("http://www.google.com.hk");
echo $httpdown->GetHtml();
$httpdown->Close();

下载文件

$file = new HttpDownload(); # 实例化类
$file->OpenUrl("http://dldir1.qq.com/qqfile/qq/QQ8.2/17724/QQ8.2.exe"); # 远程文件地址
$file->SaveToBin("qq.exe"); # 保存路径及文件名
$file->Close(); # 释放资源