Chapter 1 File Upload
1.1 Client Upload Settings
File upload has become a common function in B/S programs.The goal is that customers can upload files to a specified directory on the server (Server) through a browser (Browser).
Common web sites that support file upload:
Various disks
Portrait
Web Albums
Real-name authentication
Mail Attachments
Simply put, Web development requires users to pass files to the server in the PHP upload category.The server side can only accept copies unless it does not do this.Just like 10086 Customer Service, it accepts when you just call it. It can only accept when the server is busy.
Fundamentals of file upload in PHP:
1) Client form Settings
2) Server handles uploaded files
Form form items that must be set:
<html> <head><title>File Upload</title></head> <body> <form action="./upload.php" method="post" enctype="multipart/form-data"><!--Must write--> <!--typle write file Type, name Must write, name is free--> //Select file: <input type="file" name="myfile"> <input type="submit" value="Upload Files"> </form> </body> </html>
Notice several characteristic attributes:
1. The file must be uploaded by post, not by get.
2. Entype="multipart/form-data" must be written in the form.
3. The input form must write a name name.
1.2 Processing uploads through PHP on the server side
Receiving and processing uploaded files is handled through PHP scripts, which need three aspects of information:
1) Set up the instructions in the PH profile: for fine tuning the file upload function of PHP.
2)$FILES Multidimensional Array: used to store various information related to uploaded files, other data is obtained using $_POST.
3) File upload processing function of PHP: for subsequent processing of uploaded files.
1) Options related to file upload in the PHP configuration file.
| Instruction Name | Default value | Functional Description |
|---|---|---|
| file_uploads | ON | Whether to turn on file upload |
| upload_max_filesize | 2M | Limit the maximum upload file size for PHP processing, which must be less than post_max_size |
| post_max_size | 8M | Limits the maximum amount of information that can be accepted through the POST method, that is, the submission value for the entire POST request.This value must be greater than upload_max_filesize |
| upload_tmp_dir | NULL | The temporary path where the uploaded file is stored, which can be an absolute path.The default NULL uses the system's temporary directory. |
| max_file_uploads | 20 | Number of files allowed to be uploaded simultaneously |
2) $_FILES multidimensional array.
Super Global Array $_FILES
The value in $_FILES["myfile"]["name"] is the name of the file in the client file system.
2. $FILES["myfile"]["type"] is the type of file passed by the client.
3. The value in $_FILES ['myfile']['size'] is the size of the file's bytes.
4. $_FILES["myfile"]["tmp_name"] has a temporary full path stored on the server after the file has been uploaded.
5. $_FILES["myfile"]["error"] value is: file upload error code - php 4.2 added after the function.
Error code for error file upload:
UPLOAD_ERR_OK The value is 0, no errors occurred, and the file was uploaded successfully. UPLOAD_ERR_INI_SIZE The value is 1, and the uploaded file exceeds the upload_max_filesize option limit in php.ini. UPLOAD_ERR_FORM_SIZE The value is 2 and the size of the uploaded file exceeds the value specified by the MAX_FILE_SIZE option in the HTML form. UPLOAD_ERR_PARTIAL With a value of 3, only part of the file is uploaded. UPLOAD_ERR_NO_FILE It has a value of 4 and no files have been uploaded. UPLOAD_ERR_NO_TMP_DIR With a value of 6, the temporary folder could not be found.Introduction of PHP 4.3.10 and PHP 5.0.3. UPLOAD_ERR_CANT_WRITE With a value of 7, the file failed to write.Introduction of PHP 5.1.0. Note: The above values become PHP constants after PHP 4.3.0.
Common Data Formats (MIME)
| file type | MIME Type |
|---|---|
| Picture File | image/gif，image/jpg，image/jpeg，image/png，image/x-png |
| Plain text and HTML | text/txt，text/plain，text/html |
| Binary file | application/octet-stream |
| Audio format | audio/basic |
| Video format | video/mpeg |
3) File upload handler for PHP
Successful uploads are placed in a server-side temporary directory, where the file name is a randomly generated temporary file name.
Note: This file will be deleted automatically after the program is executed.You can act like a local file before deleting it.
File Upload Processing Function:
is_uploaded_file - Determines if the file was uploaded through HTTP POST.
Format: bool is_uploaded_file (string $filename)
move_uploaded_file - Moves the uploaded file to a new location.
Format: bool move_uploaded_file (string $filename, string $destination)
Note: If the target file already exists, it will be overwritten.
Parameter description: File temporary directory, location directory to move to
Case:
1) Set up front-end upload interface
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Document</title> </head> <body> <form action="doup.php" method="post" enctype="multipart/form-data"> <input type="file" name="pic"> <input type="submit" value="upload"> </form> </body> </html>
2) doup.php handles files uploaded to the temporary directory
//Professional handling tools //move_uploaded_file() //Parameter 1: File Temporary Directory Parameter 2: Location to move to //is_uploaded_file() to determine if the file was submitted by http post //Parameter 1: File Temporary Directory //1. Our saved paths are created by time //var_dump($_GET); //1.1 Saved Path $dir='./biran/'.date('Y/m/d/'); //echo $dir;exit; //1.2 Determine if the path to file upload exists or is created if it does not exist if(!file_exists($dir)){ mkdir($dir,777,true); } //2. Have a good filename and a unique filename //2.1 Get the suffix name of the file //2.jpg jpg $suffix = pathinfo($_FILES['pic']['name'],PATHINFO_EXTENSION); //echo $suffix; //2.2 Rename $filename = date('Ymd').uniqid().mt_rand(0,9999).'.'.$suffix; //echo $filename; //Start handling //Determine whether it is a file passed by http post if(!is_uploaded_file($_FILES['pic']['tmp_name'])){ //Not http post upload file echo 'Don't be useless!!';exit; } //Start a real move if(move_uploaded_file($_FILES['pic']['tmp_name'],$dir.$filename)){ echo '11111111111'; }else{ echo '22222222222'; }
Encapsulate as a function:
Ideas:
function upload(){ //1. Determine file upload errors //2. Determine if the type of file you upload is what you want //3. Names //4. Determine if the save path exists //5. Determine if it is an http post upload //6. Move pictures //7. Return the picture name of the successful move }
Start encapsulating functions: New function.php
<?php /* File Upload Function @param string $name name value of file upload file field @param string $dir File Save Path @param array $allow Types of files allowed to upload return string $filename Filename returns false if it fails */ function upload($name,$dir='./upload/',$allow=array('jpg','gif','jpeg','png')){ //echo $name;exit; //var_dump($_FILES);exit; //1. Determine file upload errors if($_FILES[$name]['error']>0){ //echo'upload error'; switch($_FILES[$name]['error']){ case 1: echo 'More files uploaded than php.ini in upload_max_filesize Value of Option Limit.'; break; case 2: echo 'The size of the uploaded file exceeds HTML In Form MAX_FILE_SIZE Value specified by option'; break; case 3: echo 'Only part of the file was uploaded.'; break; case 4: echo 'No files uploaded.'; break; case 6: echo 'Temporary folder not found.'; break; case 7: echo 'File Write Failure.'; break; } return false; } //2. Determine if the type of file you upload is what you want //2.1 Types of uploads allowed //2.2 Get the suffix name $suffix = pathinfo($_FILES[$name]['name'],PATHINFO_EXTENSION); //echo $suffix;exit; //2.3 Determine if we are allowed to upload //var_dump(in_array($suffix,$allow));exit; if(!in_array($suffix,$allow)){ //Type of upload not allowed echo 'Big Brother Your upload type doesn't match'; return false; } //3. Names $filename = date('Ymd').uniqid().mt_rand(0,9999).'.'.$suffix; //echo $filename;exit; //4. Determine if the save path exists //4.1 Get Saved Path //4.2 Handles save paths and slashes behind $save_path = rtrim($dir,'/'); $save_path .='/'; //4.3 Time Folder Processing in Save Path $save_path .=date('Y/m/d/'); //4.4 Determine if a saved path exists if(!file_exists($save_path)){ mkdir($save_path,777,true); } //4.5 Stitch together a complete saved path $path = $save_path.$filename; //echo $path;exit; //5. Determine if upload is httppost if(!is_uploaded_file($_FILES[$name]['tmp_name'])){ echo 'Rats, screw you!'; return false; } //6. Move pictures if(!move_uploaded_file($_FILES[$name]['tmp_name'],$path)){ echo 'Move failed'; return false; } //7. Return the picture name of the successful move return $filename; }
Call function to start uploading:
<?php include './function.php'; //var_dump($_FILES);exit; echo upload('file','./leiding',array('jpg','png'));
Chapter 2 Multi-file Upload
2.1 Multi-file upload with different name
When you need to upload more than one file, there are two solutions:
1) Use different form elements.
<input type="file" name="file_a"> <input type="file" name="file_b"> <input type="file" name="file_c">
2) Form elements in array format.
<input type="file" name="file[]"> <input type="file" name="file[]"> <input type="file" name="file[]">
Chapter 3 File Download
1) For files not recognized by browsers, they can be downloaded directly using a connection.
<!-- Because their three browsers don't recognize this type --> <a href="./downlist/1.rar">1.rar</a> <a href="./downlist/1.exe">1.exe</a> <a href="./downlist/1.avi">1.avi</a>
2) If the browser does not recognize it, you can use the readfile function.
<!-- Browsers recognize this type,Will be resolved --> <a href="./action.php?name=1.html">1.html</a> <a href="./action.php?name=1.php">1.php</a> <a href="./action.php?name=1.txt">1.txt</a> <a href="./action.php?name=1.jpg">1.jpg</a>
//Receive the name value. $name = $_GET['name']; //Implement download capability //Force browser to pop up Save As dialog header('content-Disposition:attachment;filename="'.$name.'"'); //At this point, only an empty file is downloaded, you need to read through all the contents with readfile. You can download it. $path = './downlist/'.$name; readfile($path);