<?php
/**
 * 下載遠程文件類支持斷點續傳
 */
class HttpDownload {
  private $m_url = "";
  private $m_urlpath = "";
  private $m_scheme = "http";
  private $m_host = "";
  private $m_port = "80";
  private $m_user = "";
  private $m_pass = "";
  private $m_path = "/";
  private $m_query = "";
  private $m_fp = "";
  private $m_error = "";
  private $m_httphead = "" ;
  private $m_html = "";
  /**
   * 初始化
   */
  public function PrivateInit($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;
      }
    }
  }
  /**
  * 打開指定網址
  */
  function OpenUrl($url) {
    #重設各參數
    $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();
    #初始化系統
    $this->PrivateInit($url);
    $this->PrivateStartSession();
  }
  /**
  * 獲得某操作錯誤的原因
  */
  public function printError() {
    echo "錯誤信息：".$this->m_error;
    echo "具體返回頭：<br>";
    foreach($this->m_httphead as $k=>$v) {
      echo "$k => $v <br>\r\n";
    }
  }
  /**
  * 判別用Get方法發送的頭的應答結果是否正確
  */
  public function IsGetOK() {
    if( ereg("^2",$this->GetHead("http-state")) ) {
      return true;
    } else {
      $this->m_error .= $this->GetHead("http-state")." - ".$this->GetHead("http-describe")."<br>";
      return false;
    }
  }
  /**
  * 看看返回的網頁是否是text類型
  */
  public function IsText() {
    if (ereg("^2",$this->GetHead("http-state")) && eregi("^text",$this->GetHead("content-type"))) {
      return true;
    } else {
      $this->m_error .= "內容為非文本類型<br>";
      return false;
    }
  }
  /**
  * 判斷返回的網頁是否是特定的類型
  */
  public function IsContentType($ctype) {
    if (ereg("^2",$this->GetHead("http-state")) && $this->GetHead("content-type") == strtolower($ctype)) {
      return true;
    } else {
      $this->m_error .= "類型不對 ".$this->GetHead("content-type")."<br>";
      return false;
    }
  }
  /**
  * 用 HTTP 協議下載文件
  */
  public function SaveToBin($savefilename) {
    if (!$this->IsGetOK()) return false;
    if (@feof($this->m_fp)) {
      $this->m_error = "連接已經關閉！";
      return false;
    }
    $fp = fopen($savefilename,"w") or die("寫入文件 $savefilename 失敗！");
    while (!feof($this->m_fp)) {
      @fwrite($fp,fgets($this->m_fp,256));
    }
    @fclose($this->m_fp);
    return true;
  }
  /**
  * 保存網頁內容為 Text 文件
  */
  public function SaveToText($savefilename) {
    if ($this->IsText()) {
      $this->SaveBinFile($savefilename);
    } else {
      return "";
    }
  }
  /**
  * 用 HTTP 協議獲得一個網頁的內容
  */
  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 $this->m_html;
  }
  /**
  * 開始 HTTP 會話
  */
  public function PrivateStartSession() {
    if (!$this->PrivateOpenHost()) {
      $this->m_error .= "打開遠程主機出錯!";
      return false;
    }
    if ($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($this->m_fp,"User-Agent: Mozilla/4.0+(compatible;+MSIE+6.0;+Windows+NT+5.2)\r\n");
    #HTTP1.1協議必須指定文檔結束后關閉鏈接,否則讀取文檔時無法使用feof判斷結束
    if ($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($lines[1]);
      }
    }
  }
  /**
  * 獲得一個Http頭的值
  */
  public function GetHead($headname) {
    $headname = strtolower($headname);
    if (isset($this->m_httphead[$headname])) {
      return $this->m_httphead[$headname];
    } else {
      return "";
    }
  }
  /**
  * 打開連接
  */
  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 = $errstr;
      return false;
    } else {
      return true;
    }
  }
  /**
  * 關閉連接
  */
  public function Close(){
    @fclose($this->m_fp);
  }
}
#兩種使用方法，分別如下：
#打開網頁
$httpdown = new HttpDownload();
$httpdown->OpenUrl("http://www.google.com.hk");
echo $httpdown->GetHtml();
$httpdown->Close();
#下載文件
$file = new HttpDownload(); # 實例化類
$file->OpenUrl("http://www.ti.com.cn/cn/lit/an/rust020/rust020.pdf"); # 遠程文件地址
$file->SaveToBin("rust020.pdf"); # 保存路徑及文件名
$file->Close(); # 釋放資源
?>