PHP download remote file class (supports breakpoint resume download)_PHP tutorial

<?php
/**
 * 下载远程文件类支持断点续传 
 */
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：".$this->m_error;
		echo "具体返回头：<br>";
		foreach($this->m_httphead as $k=>$v) { 
			echo "$k => $v <br>rn"; 
		}
	}
 
	/**
	* 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")."<br>";
			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 {
			$this->m_error .= "内容为非文本类型<br>";
			return false;
		}
	}
	/**
	* 判断返回的网页是否是特定的类型
	*/
	public function IsContentType($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")."<br>";
			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." $httpvrn");
		fputs($this->m_fp,"Host: ".$this->m_host."rn");
		fputs($this->m_fp,"Accept: */*rn");
		fputs($this->m_fp,"User-Agent: Mozilla/4.0+(compatible;+MSIE+6.0;+Windows+NT+5.2)rn");
		#HTTP1.1协议必须指定文档结束后关闭链接,否则读取文档时无法使用feof判断结束
		if ($httpv=="HTTP/1.1") {
			fputs($this->m_fp,"Connection: Closernrn");
		} else {
			fputs($this->m_fp,"rn");
		}
		$httpstas = fgets($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://www.ti.com.cn/cn/lit/an/rust020/rust020.pdf"); # 远程文件地址
$file->SaveToBin("rust020.pdf"); # 保存路径及文件名
$file->Close(); # 释放资源
?>