Using file functions to implement PHP file upload case analysis_PHP tutorial

If you are a computer enthusiast and don’t know PHP, you are too behind the times. If you want to know the relevant knowledge of PHP, let’s take a look at the implementation of PHP file upload. This code is divided into two files, one is upload.html and the other is upload.php.

<ol class="dp-xml">
<li class="alt">
<span><strong><font color="#006699"><span class="tag"><</SPAN><SPAN class=tag-name>form</SPAN></FONT></STRONG><SPAN> </SPAN><SPAN class=attribute><FONT color=#ff0000>enctype</FONT></SPAN><SPAN>=</SPAN><SPAN class=attribute-value><FONT color=#0000ff>"multipart/form-data"</FONT></SPAN><SPAN> </SPAN><SPAN class=attribute><FONT color=#ff0000>action</FONT></SPAN><SPAN>=</SPAN><SPAN class=attribute-value><FONT color=#0000ff>"upload.php"</FONT></SPAN><SPAN> </SPAN><SPAN class=attribute><FONT color=#ff0000>method</FONT></SPAN><SPAN>=</SPAN><SPAN class=attribute-value><FONT color=#0000ff>"post"</FONT></SPAN><SPAN class=tag><STRONG><FONT color=#006699>></span></font></strong></span><span> </span>
</li>
<li class="">
<span></span><strong><font color="#006699"><span class="tag"><</SPAN><SPAN class=tag-name>input</SPAN></FONT></STRONG><SPAN> </SPAN><SPAN class=attribute><FONT color=#ff0000>type</FONT></SPAN><SPAN>=</SPAN><SPAN class=attribute-value><FONT color=#0000ff>"hidden"</FONT></SPAN><SPAN> </SPAN><SPAN class=attribute><FONT color=#ff0000>name</FONT></SPAN><SPAN>=</SPAN><SPAN class=attribute-value><FONT color=#0000ff>"max_file_size"</FONT></SPAN><SPAN> </SPAN><SPAN class=attribute><FONT color=#ff0000>value</FONT></SPAN><SPAN>=</SPAN><SPAN class=attribute-value><FONT color=#0000ff>"100000"</FONT></SPAN><SPAN class=tag><STRONG><FONT color=#006699>></span></font></strong><span> </span>
</li>
<li class="alt">
<span></span><strong><font color="#006699"><span class="tag"><</SPAN><SPAN class=tag-name>input</SPAN></FONT></STRONG><SPAN> </SPAN><SPAN class=attribute><FONT color=#ff0000>name</FONT></SPAN><SPAN>=</SPAN><SPAN class=attribute-value><FONT color=#0000ff>"userfile"</FONT></SPAN><SPAN> </SPAN><SPAN class=attribute><FONT color=#ff0000>type</FONT></SPAN><SPAN>=</SPAN><SPAN class=attribute-value><FONT color=#0000ff>"file"</FONT></SPAN><SPAN class=tag><STRONG><FONT color=#006699>></span></font></strong><span>  </span>
</li>
<li class="">
<span></span><strong><font color="#006699"><span class="tag"><</SPAN><SPAN class=tag-name>input</SPAN></FONT></STRONG><SPAN> </SPAN><SPAN class=attribute><FONT color=#ff0000>type</FONT></SPAN><SPAN>=</SPAN><SPAN class=attribute-value><FONT color=#0000ff>"submit"</FONT></SPAN><SPAN> </SPAN><SPAN class=attribute><FONT color=#ff0000>value</FONT></SPAN><SPAN>=</SPAN><SPAN class=attribute-value><FONT color=#0000ff>"上传文件"</FONT></SPAN><SPAN class=tag><STRONG><FONT color=#006699>></span></font></strong><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>
</ol>

Among them, please note that

This is a tag, If we want to upload files, we must specify multipart/form-data, otherwise the server will not know what to do. It is worth noting that the hidden value field of the form option MAX_FILE_SIZE in the file upload.html can limit the size of the uploaded file by setting its Value. The value of MAX_FILE_SIZE is just a suggestion for browsers, and it can be easily bypassed. So don't rely on this value to limit browser restrictions. In fact, the maximum value for PHP file upload in PHP settings will not be invalid. But it's better to include MAX_FILE_SIZE in the form, as it saves users the trouble of spending time waiting for a large file to be uploaded only to find out that the file is too big.

<ol class="dp-xml">
<li class="alt"><span><span>upload.php  </span></span></li>
<li class="">
<span>$</span><span class="attribute"><font color="#ff0000">f</font></span><span>=&$HTTP_POST_FILES['Myfile'];  </span>
</li>
<li class="alt">
<span>$</span><span class="attribute"><font color="#ff0000">dest_dir</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">'uploads'</font></span><span>;//设定上传目录  </span>
</li>
<li class="">
<span>$</span><span class="attribute"><font color="#ff0000">dest</font></span><span>=$dest_dir.'/'.date("ymd")."_".$f['name'];//设置文件名为日期加上文件名避免重复  </span>
</li>
<li class="alt">
<span>$</span><span class="attribute"><font color="#ff0000">r</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">move_uploaded_file</font></span><span>($f['tmp_name'],$dest);  </span>
</li>
<li class=""><span>chmod($dest, 0755);//设定上传的文件的属性 </span></li>
</ol>

or

<ol class="dp-xml"><li class="alt">
<span><strong><font color="#006699"><span class="tag"><?</SPAN><SPAN class=tag-name>copy</SPAN></FONT></STRONG><SPAN>($_FILES[MyFile][tmp_name],$_FILES[MyFile][name]);</SPAN><SPAN class=tag><STRONG><FONT color=#006699>?></span></font></strong></span><span> </span>
</li></ol>

The contents of the $_FILES array in the above example are as follows. We assume that the name of the file upload field is userfile (the name can be named arbitrarily)

<ol class="dp-xml">
<li class="alt"><span><span>$_FILES['userfile']['name']//客户端机器文件的原名称。  </span></span></li>
<li class=""><span>$_FILES['userfile']['type'] //文件的 MIME 类型，需要浏览器提供该信息的支持，例如“image/gif”。  </span></li>
<li class="alt"><span>$_FILES['userfile']['size']// 已上传文件的大小，单位为字节。  </span></li>
<li class=""><span>$_FILES['userfile']['tmp_name'] //文件被上传后在服务端储存的临时文件名。  </span></li>
<li class="alt"><span>$_FILES['userfile']['error'] //和该文件上传相关的错误代码 </span></li>
</ol>

PHP file upload value analysis:
◆Value: 0; No error occurs and the file upload is successful.
◆Value: 1; The uploaded file exceeds the limit of the upload_max_filesize option in php.ini.
◆Value: 2; The size of the uploaded file exceeds the value specified by the MAX_FILE_SIZE option in the HTML form.
◆Value: 3; Only part of the file was uploaded.
◆Value: 4; No files were uploaded.

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