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本文介绍下,在php中,实现下载文件的一些方法与代码,包括系统函数调用、wget、以及socket连接方式下载文件等。有需要的朋友作个参考吧。
在php中实现下载文件,方法大多是如下二种: 一种是使用system、exec等即有的函数调用系统自带的下载工具,比如 wget 之类的来下载文件。 另一种是使用php本身利用Socket来下载文件。 笔者喜欢用第二种方式。 使用Socket下载文件,如果是http协议的文件,必须明白HTTP协议的运行过程,如果是FTP协议的则要了解ftp协议运行过程。 比如HTTP协议访问一个文件: <?php $fp = fsockopen("www.example.com", 80, $errno, $errstr, 30); if (!$fp) { echo "$errstr ($errno)<br />\n"; } else { $out = "GET / HTTP/1.1\r\n"; $out .= "Host: www.example.com\r\n"; $out .= "Connection: Close\r\n\r\n"; fwrite($fp, $out); while (!feof($fp)) { echo fgets($fp, 128); } fclose($fp); } ?> 使用fopen直接访问远程文件来达到目的,同时又可以访问http,也能访问ftp。 当然,如果按照上面的思路来说,也可以使用ftp的函数库来实现。 使用fopen函数的例子: #! /usr/bin/php <?php error_reporting(0); set_time_limit(0); //无参数则给出提示 if ($argc < 2){ echo "Usage: ". $argv[0] ." URL [Destination]\n\n"; exit(); } //设置获取基本变量 $url = $argv[1]; $save_path = $argv[2] ? $argv[2] : "./"; $file_name = array_pop(explode("/", $url)); $localfile = $save_path . $file_name; //检查变量 if (!check_url($url)){ exit("Error: URL ". $url ." invalid.\n\n"); } if (file_exists($localfile)){ exit("Error: local file ". $localfile ." exists.\n\n"); } //打开远程文件 $fp = fopen($url, "rb"); if (!$fp){ exit("Error: Download ". $url ." failed.\n\n"); } //打开本地文件 $sp = fopen($localfile, "wb"); if (!$sp){ exit("Error: Open local file ". $localfile ." failed.\n\n"); } //下载远程文件 echo "Downloading, please waiting...\n\n"; while (!feof($fp)){ $tmpfile .= fread($fp, 1024); } //保存文件到本地 fwrite($sp, $tmpfile); fclose($fp); fclose($sp); echo "Download file ". $file_name ." succeed!\n\n"; /* 检查URL合法性函数 */ function check_url($url){ return preg_match("/^(http|ftp)(:\/\/)([a-zA-Z0-9-_]+[\.\/]+[\w\-_\/]+.*)+$/i", $url); } ?> 以上代码保存为 download.php 文件,加上可执行属性: chmod +x download.php 执行,注意脚本的路径要正确: #! /usr/local/php/bin/php 使用上面的脚本来下载文件: download.php 远程文件 保存路径 如把Google Talk程序下载到我们的 /tmp 目录下: download.php http://dl.google.com/googletalk/googletalk-setup.exe /tmp/ 如果不出错,等待一会就能够在 /tmp/ 目录下看到 googletalk-setup.exe 文件。 这里分享一个更强的HTTP下载类: <? /*================= // 织梦Http下载类 =======================*/ 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 $m_html = ""; // //初始化系统 // function PrivateInit($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); $this->PrivateStartSession(); } // //获得某操作错误的原因 // function printError() { echo "错误信息:".$this->m_error; echo "具体返回头:<br>"; foreach($this->m_httphead as $k=>$v) { echo "$k => $v <br>\r\n"; } } // //判别用Get方法发送的头的应答结果是否正确 // function IsGetOK() { if( ereg("^2",$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 // function IsText() { if(ereg("^2",$this->GetHead("http-state")) && eregi("^text",$this->GetHead("content-type"))) { return true; } else { $this->m_error .= "内容为非文本类型<br>"; return false; } } // //判断返回的网页是否是特定的类型 // function IsContentType($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 // 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($this->m_fp); return true; } // //保存网页内容为Text文件 // function SaveToText($savefilename) { if($this->IsText()) $this->SaveBinFile($savefilename); else return ""; } // //用Http协议获得一个网页的内容 // 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 $this->m_html; } // //开始HTTP会话 // function PrivateStartSession() { if(!$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($lines[1]); } } } // //获得一个Http头的值 // function GetHead($headname) { $headname = strtolower($headname); if(isset($this->m_httphead[$headname])) return $this->m_httphead[$headname]; else return ""; } // //打开连接 // 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 = $errstr; return false; } else{ return true; } } // //关闭连接 // function Close(){ @fclose($this->m_fp); } } ?> 调用示例: 1,下载网页 <? $httpdown = new DedeHttpDown(); $httpdown->OpenUrl("http://bbs.it-home.org"); echo $httpdown->GetHtml(); $httpdown->Close(); ?> 2,下载图片并保存 <? $httpdown = new DedeHttpDown(); $httpdown->OpenUrl("http://img.jbxue.com/images/1.jpg"); echo $httpdown->SaveBin("test.jpg"); $httpdown->Close(); echo "<img src='test.jpg' alt="php 下载文件的代码分享 " >"; ?> |