使用PHP下载文件

使用PHP脚本来下载文件，无非是通过两种方式，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，还有一种是使用php本身利用Socket来下载文件，我选择第二种方式。

使用Socket下载文件，首先如果是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，比较繁琐。比如HTTP协议访问一个文件的代码：（来自手册）

<?php

$fp = fsockopen("www.example.com", 80, $errno, $errstr, 30);

if (!$fp) {

echo "$errstr ($errno) \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);

}

我们为了简单起见，使用fopen直接访问远程文件来达到目的，同事又能够访问http，也能访问ftp，比较合适。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。

我们使用fopen函数来完成我们的工作，实现了如下代码：

#! /usr/bin/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);

我们把以上代码保存为 download.php 文件，在Linux/Unix下记得要加上可执行属性：

chmod +x download.php

另外，PHP脚本引擎的路径必须是 /usr/bin/php ，如果不是，请自行修改第一行为实际的PHP引擎路径，比如：

#! /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。

能够改进的就是支持更多协议、需要验证的能够输入用户名密码、有下载进度条。至于断点续传和多线程对于PHP来说还不太现实，有兴趣的可以自己加深一步。

PS: 我另外发现一个更强的HTTP下载类，是dedeCMS的作者IT柏拉图写的:

/*=======================================

// 织梦Http下载类

// 织梦之旅 www.dedecms.com

=======================================*/

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： ";

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

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

function IsText()

if(ereg("^2",$this->GetHead("http-state"))

&& eregi("^text",$this->GetHead("content-type")))

$this->m_error .= "内容为非文本类型 ";

//判断返回的网页是否是特定的类型

function IsContentType($ctype)

&& $this->GetHead("content-type")==strtolower($ctype))

$this->m_error .= "类型不对 ".$this->GetHead("content-type")." ";

//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 "";

$this->m_html .= fgets($this->m_fp,256);

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!";

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]);

$line = str_replace("\"","",trim(fgets($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];

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;

else{

return true;

//关闭连接

function Close(){

----------------------------------------------------------------------------------

这个类的使用方法：

下载网页

$httpdown = new DedeHttpDown();

$httpdown->OpenUrl("http://www.dedecms.com");

echo $httpdown->GetHtml();

$httpdown->Close();

如果下载图片并保存,可以用

$httpdown->OpenUrl("http://prato.bokele.com/0/0/399/bGluMi5qcGc=.jpg");

echo $httpdown->SaveBin("test.jpg");

echo "<img src='test.jpg'>";

使用PHP下载文件

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