三步FTP实现PHP上传文件代码剖析

想知道上传文件的详细步骤吗，下面我就带大家一起详细分析一下吧。利用PHP，你总是可以有多种方式来完成某个特定的任务。我们就拿文件上传举个例子。当然了，你可以按照传统的方式来使用HTTP文件上传，把文件直接传输到Web服务器磁盘上。你还可以用更加奇异的方式上传，用FTP协议两步就完成上传：从你的本地硬盘到Web服务器，然后再到FTP服务器。

PHP在本机同时支持FTP和HTTP上传，所以你可以根据自己应用程序的设计需要进行最佳的选择。使用PHP的FTP函数进行文件传输几乎与使用传统的FTP客户端相同——你会看到连函数的名字都和标准的FTP命令类似。关于HTTP文件上传的文章已经多得满天飞了，这就是为什么本文有必要把注意力放在基于FTP的文件上传上了（但是在后面给出的例子中，两种方式你都会看到）。要注意的是，本教程假设你已经安装好了PHP／Apache，而且HTTP文件上传和FTP的函数都已经激活了。本文可以从这里下载，所有的源代码都以单独的文本方式列出来了。

第一步：确信你拥有连接／上传到FTP服务器的权限

PHP的FTP函数需要客户端－服务器连接，所以你需要在进行文件上传之前登录到目标服务器上。你的第一项任务是确信你已经拥有了完成这项任务的信任书。这一步可能看起来是理所当然的，但是你会惊奇地发现有多少开发人员忘了这么做，结果后来浪费大量的时间来解决因此而出现的问题。你可以通过使用命令行的FTP客户端登录到目标服务器上，以检查连接状况并尝试上传一个假文件。

PHP上传文件代码列表A

<ol class="dp-xml">
<li class="alt"><span><span>$ftp  </span></span></li>
<li class="">
<span>ftp</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>opensome.host.com  </span>
</li>
<li class="alt"><span>Connectedtosome.host.com.  </span></li>
<li class=""><span>220WelcometoleonFTPServer!  </span></li>
<li class="alt"><span>User:upload  </span></li>
<li class=""><span>331Useruploadokay,needpassword.  </span></li>
<li class="alt"><span>Password:***  </span></li>
<li class=""><span>230Restricteduserloggedin.  </span></li>
<li class="alt">
<span>ftp</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>bin  </span>
</li>
<li class=""><span>200Typeokay.  </span></li>
<li class="alt">
<span>ftp</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>hash  </span>
</li>
<li class=""><span>HashmarkprintingOn?ftp:(2048bytes/hashmark).  </span></li>
<li class="alt">
<span>ftp</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>putfile.bin  </span>
</li>
<li class=""><span>200PORTcommandsuccessful.  </span></li>
<li class="alt"><span>150OpeningBINARYmodedataconnection.  </span></li>
<li class=""><span>##  </span></li>
<li class="alt"><span>226Transfercompleted.  </span></li>
<li class=""><span>ftp:4289bytessentin0.00Seconds4289000.00Kbytes/sec.  </span></li>
<li class="alt">
<span>ftp</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>bye  </span>
</li>
<li class=""><span>221Goodbye. </span></li>
</ol>

一旦确认有相关的访问权限，你就可以登录出来。

第二步：创建上传表单

然后，创建一个简单的HTML表单，向用户询问重要的参数——FTP服务器的访问信息、服务器上传的目录，以及完整的目录和上传文件的名字。下面这个例子就是这个表单的样式。

PHP上传文件代码列表B

<ol class="dp-xml">
<li class="alt"><span><strong><font color="#006699"><span class="tag"><span class="tag-name">html</span><span class="tag">></span></span></font></strong><span> </span></span></li>
<li class="">
<span></span><strong><font color="#006699"><span class="tag"><span class="tag-name">head</span><span class="tag">></span><span class="tag"></span><span class="tag-name">head</span><span class="tag">></span></span></font></strong><span> </span>
</li>
<li class="alt">
<span></span><strong><font color="#006699"><span class="tag"><span class="tag-name">body</span><span class="tag">></span></span></font></strong><span> </span>
</li>
<li class="">
<span></span><strong><font color="#006699"><span class="tag"><span class="tag-name">h2</span><span class="tag">></span></span></font></strong><span>Pleaseprovidethefollowinginformation:</span><strong><font color="#006699"><span class="tag"></span><span class="tag-name">h2</span><span class="tag">></span></font></strong><span> </span>
</li>
<li class="alt"><span> </span></li>
<li class="">
<span></span><span class="tag"><strong><font color="#006699"></font></strong></span><span class="attribute"><font color="#ff0000">formenctype</font></span><span class="tag-name"><strong><font color="#006699">formenctype</font></strong></span><span>="multipart/form-data"</span><span class="attribute-value"><font color="#0000ff">method</font></span><span>="post"</span><span class="attribute"><font color="#ff0000">action</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">"upload.php"</font></span><span class="tag"><strong><font color="#006699">></font></strong></span><span> </span>
</li>
<li class="alt">
<span></span><span class="tag"><strong><font color="#006699"></font></strong></span><span class="attribute"><font color="#ff0000">inputtype</font></span><span class="tag-name"><strong><font color="#006699">inputtype</font></strong></span><span>="hidden"</span><span class="attribute-value"><font color="#0000ff">name</font></span><span>="MAX_FILE_SIZE"</span><span class="attribute"><font color="#ff0000">value</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">"5000000"</font></span><span class="tag"><strong><font color="#006699">/></font></strong></span><span> </span>
</li>
<li class="">
<span>Host</span><strong><font color="#006699"><span class="tag"><span class="tag-name">br</span><span class="tag">/></span></span></font></strong><span> </span>
</li>
<li class="alt">
<span></span><span class="tag"><strong><font color="#006699"></font></strong></span><span class="attribute"><font color="#ff0000">inputtype</font></span><span class="tag-name"><strong><font color="#006699">inputtype</font></strong></span><span>="text"</span><span class="attribute-value"><font color="#0000ff">name</font></span><span>="host"</span><strong><font color="#006699"><span class="tag">/></span><span class="tag"><span class="tag-name">p</span><span class="tag">/></span></span></font></strong><span> </span>
</li>
<li class="">
<span>Username</span><strong><font color="#006699"><span class="tag"><span class="tag-name">br</span><span class="tag">/></span></span></font></strong><span> </span>
</li>
<li class="alt">
<span></span><span class="tag"><strong><font color="#006699"></font></strong></span><span class="attribute"><font color="#ff0000">inputtype</font></span><span class="tag-name"><strong><font color="#006699">inputtype</font></strong></span><span>="text"</span><span class="attribute-value"><font color="#0000ff">name</font></span><span>="user"</span><strong><font color="#006699"><span class="tag">/></span><span class="tag"><span class="tag-name">p</span><span class="tag">/></span></span></font></strong><span> </span>
</li>
<li class="">
<span>Password</span><strong><font color="#006699"><span class="tag"><span class="tag-name">br</span><span class="tag">/></span></span></font></strong><span> </span>
</li>
<li class="alt">
<span></span><span class="tag"><strong><font color="#006699"></font></strong></span><span class="attribute"><font color="#ff0000">inputtype</font></span><span class="tag-name"><strong><font color="#006699">inputtype</font></strong></span><span>="password"</span><span class="attribute-value"><font color="#0000ff">name</font></span><span>="pass"</span><strong><font color="#006699"><span class="tag">/></span><span class="tag"><span class="tag-name">p</span><span class="tag">/></span></span></font></strong><span> </span>
</li>
<li class="">
<span>Destinationdirectory</span><strong><font color="#006699"><span class="tag"><span class="tag-name">br</span><span class="tag">/></span></span></font></strong><span> </span>
</li>
<li class="alt">
<span></span><span class="tag"><strong><font color="#006699"></font></strong></span><span class="attribute"><font color="#ff0000">inputtype</font></span><span class="tag-name"><strong><font color="#006699">inputtype</font></strong></span><span>="text"</span><span class="attribute-value"><font color="#0000ff">name</font></span><span>="dir"</span><strong><font color="#006699"><span class="tag">/></span><span class="tag"><span class="tag-name">p</span><span class="tag">/></span></span></font></strong><span> </span>
</li>
<li class="">
<span>File</span><strong><font color="#006699"><span class="tag"><span class="tag-name">br</span><span class="tag">/></span></span></font></strong><span> </span>
</li>
<li class="alt">
<span></span><span class="tag"><strong><font color="#006699"></font></strong></span><span class="attribute"><font color="#ff0000">inputtype</font></span><span class="tag-name"><strong><font color="#006699">inputtype</font></strong></span><span>="file"</span><span class="attribute-value"><font color="#0000ff">name</font></span><span>="file"</span><strong><font color="#006699"><span class="tag">/></span><span class="tag"><span class="tag-name">p</span><span class="tag">/></span></span></font></strong><span> </span>
</li>
<li class="">
<span></span><span class="tag"><strong><font color="#006699"></font></strong></span><span class="attribute"><font color="#ff0000">inputtype</font></span><span class="tag-name"><strong><font color="#006699">inputtype</font></strong></span><span>="submit"</span><span class="attribute-value"><font color="#0000ff">name</font></span><span>="submit"</span><span class="attribute"><font color="#ff0000">value</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">"UploadFile"</font></span><span class="tag"><strong><font color="#006699">/></font></strong></span><span> </span>
</li>
<li class="alt">
<span></span><strong><font color="#006699"><span class="tag"></span><span class="tag-name">form</span><span class="tag">></span></font></strong><span> </span>
</li>
<li class="">
<span></span><strong><font color="#006699"><span class="tag"></span><span class="tag-name">body</span><span class="tag">></span></font></strong><span> </span>
</li>
<li class="alt">
<span></span><strong><font color="#006699"><span class="tag"></span><span class="tag-name">html</span><span class="tag">></span></font></strong><span> </span>
</li>
</ol>

在这里，元素用来生成文件选择对话框，用户通过它来选择要被上传的文件。元素然后就把表单数据编码成为多个部分提交，这可以让PHP更容易地识别提交的文件组件。

第三步：创建PHP上传处理程序

一旦表单被提交给了Web服务器，下一步（也是最后一步）是使用PHP的FTP函数按照用户提供的访问信任书把它传输到目标服务器上。下面就是完成上述所有工作的脚本（upload.php）。

PHP上传文件代码列表C

<ol class="dp-xml">
<li class="alt"><span><span class="tag"></span><span class="tag-name">php</span><span> </span></span></li>
<li class=""><span>//getFTPaccessparameters  </span></li>
<li class="alt">
<span>$</span><span class="attribute">host</span><span>=$_POST['host'];  </span>
</li>
<li class="">
<span>$</span><span class="attribute">user</span><span>=$_POST['user'];$</span><span class="attribute">pass</span><span>=$_POST['pass'];  </span>
</li>
<li class="alt">
<span>$</span><span class="attribute">destDir</span><span>=$_POST['dir'];  </span>
</li>
<li class="">
<span>$</span><span class="attribute">workDir</span><span>=</span><span class="attribute-value">"/usr/local/temp"</span><span>;//definethisasperlocalsystem  </span>
</li>
<li class="alt"><span>//gettemporaryfilenamefortheuploadedfile  </span></li>
<li class="">
<span>$</span><span class="attribute">tmpName</span><span>=</span><span class="attribute-value">basename</span><span>($_FILES['file']['tmp_name']);  </span>
</li>
<li class="alt"><span>//copyuploadedfileintocurrentdirectory  </span></li>
<li class=""><span>move_uploaded_file($_FILES['file']['tmp_name'],$workDir."/".$tmpName)ordie("Cannotmoveuploadedfiletoworkingdirectory");  </span></li>
<li class="alt"><span>//openconnection  </span></li>
<li class="">
<span>$</span><span class="attribute">conn</span><span>=</span><span class="attribute-value">ftp_connect</span><span>($host)ordie("Cannotinitiateconnectiontohost");  </span>
</li>
<li class="alt"><span>//sendaccessparameters  </span></li>
<li class=""><span>ftp_login($conn,$user,$pass)ordie("Cannotlogin");  </span></li>
<li class="alt"><span>//performfileupload  </span></li>
<li class="">
<span>$</span><span class="attribute">upload</span><span>=</span><span class="attribute-value">ftp_put</span><span>($conn,$destDir."/".$_FILES['file']['name'],$workDir."/".$tmpName,FTP_BINARY);  </span>
</li>
<li class="alt"><span>//checkuploadstatus  </span></li>
<li class=""><span>//displaymessage  </span></li>
<li class="alt"><span>if(!$upload){  </span></li>
<li class=""><span>echo"Cannotupload";  </span></li>
<li class="alt"><span>}else{  </span></li>
<li class=""><span>echo"Uploadcomplete";  </span></li>
<li class="alt"><span>}  </span></li>
<li class=""><span>//closetheFTPstream  </span></li>
<li class="alt"><span>ftp_close($conn);  </span></li>
<li class=""><span>//deletelocalcopyofuploadedfile  </span></li>
<li class="alt"><span>unlink($workDir."/".$tmpName)ordie("Cannotdeleteuploadedfilefromworkingdirectory--manualdeletionrecommended");  </span></li>
<li class="">
<span></span><span class="tag">?></span><span> </span>
</li>
</ol>