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The example of this article analyzes the PHP file upload operation. Share it with everyone for your reference, the details are as follows:
File upload
occurs in the request sent by the browser to the server.
File, for the browser, is just a special type of data in the form.
Data in the browser form, two types:
String type (byte stream encoding)
File type (binary encoding), the file is in the form data Part of
Server perspective:
Process the data in the form when accepting the browser request. Different processing methods are used according to different data types:
String type, stored in the $_POST variable (memory)
File type data, stored in the upload temporary directory
When the form is submitted, the browser will behave as follows:
The content in the form is of string type. Even if a file field is added, attributes need to be added to the form to inform the browser that more than just strings are uploaded. type data. enctype="multipart/form-data"
<body> <form action="upload.php" method="post" enctype="multipart/form-data"> <input type="file" name="file"> </br> <input type="submit" value="submit"> </form> </body>
After the php server receives the form data of the file type, it stores the file in a temporary directory (it is a temporary file and is valid within the script cycle)
; Temporary directory for HTTP uploaded files (will use system default if not ; specified). ; http://php.net/upload-tmp-dir ;upload_tmp_dir =
Persistently store temporary files
move_uploaded_file(src_url,goa_url)
$_FILES, which stores uploaded file information including temporary addresses
Error type:
0-1-2-3-4-6-7
0 means there is no error
1 means the file is larger than the php setting
; Maximum allowed size for uploaded files. ; http://php.net/upload-max-filesize upload_max_filesize = 2M
2 means the file is larger than the form setting max_file_size
<input type='hidden' name='MAX_FILE_SIZE' value='1024'>
3 means that the file upload is incomplete
4 means that no file is uploaded
5 means that a 0-byte file (empty file) is logically uploaded
6 means the temporary upload directory was not found (insufficient permissions)
7 means file writing failed (disk space, permissions)
Maximum number of uploaded files allowed by php
; Maximum number of files that can be uploaded via a single request max_file_uploads = 20
There is a maximum value limit for post
Once exceeded, PHP cannot process post and file values normally and may be empty values
; Maximum size of POST data that PHP will accept. ; http://php.net/post-max-size post_max_size = 8M
In type detection
The suffix name and mime are both browse Provided by the server, PHP extension fileinfo is required to complete the check of file information (function process and object-oriented)
;extension=php_fileinfo.dll
$finfo = new Finfo(FILEINFO_MIME_TYPE); $mine_type = $finfo->file($file['tmp_name']);
Molecular directory storage uploaded files
Principle: business logic, number of files, time
Create directory mkdir()
Check directory is_dir()
<?php upload($_FILES['file']); function upload($file){ if($file['error']!=0){ return false; } //3M $max_size = 3145728; if($max_size<$file['size']){ return false; } //设置一个后缀名与mime的映射关系 $type_map = array( '.jpeg'=>array('image/jpeg','image/pjpeg'), '.jpg'=>array('image/jpeg','image/pjpeg'), '.png'=>array('image/png','image/x-png'), '.gif'=>array('image/gif') ); //后缀 $allow_ext_list = array('.jpeg','.png','.jpg'); $ext = strtolower(strrchr($file['name'],'.')); if(!in_array($ext,$allow_ext_list)){ echo '不支持该图片格式'; return false; } //MIME $allow_mime_list = array(); foreach($allow_ext_list as $val){ $allow_mime_list = array_merge($allow_mime_list,$type_map[$val]); } //浏览器提供信息坚持 $allow_mime_list = array_unique($allow_mime_list); if(!in_array($file['type'],$allow_mime_list)){ echo '不支持该图片格式'; return false; } //php自身检查 $file_mime = new Finfo(FILEINFO_MIME_TYPE); $mime = $file_mime->file($file['tmp_name']); if(!in_array($mime,$allow_mime_list)){ echo '不支持该图片格式'; return false; } //目录存储 $up_loadpath = './'; $sub_dir = date('Ymdh'); if(!is_dir($up_loadpath.$sub_dir)){ mkdir($up_loadpath.$sub_dir); } $prefix = 'bee_'; $name = uniqid($prefix,true).$ext; if(move_uploaded_file($file['tmp_name'],$up_loadpath.$sub_dir.$name)){ echo '上传成功'; return $name; }else{ echo '上传失败'; return false; } }
I hope this article will be useful to everyone in PHP programming. helped.
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