PHP file upload guide_PHP tutorial

1. Form part
Allows users to upload files. An upload attribute must be added to the declaration of the HTML form:
enctype = 'multipart/form-data'
Method of the form Must be the POST
form option MAX_FILE_SIZE hidden field used to limit the upload file size. It must be placed in front of the file form element, in bytes.
For example:

Copy code The code is as follows:

2. Processing uploaded files
When uploading, PHP receives an array of information about the file, which can be found in the super global array $_FILES.
For example: If the name of the file input box in the form is upload_file, then all information about the file is contained in the array $_FILES['upload_file']. " /tmp/phpjksdf" The temporary file name on the server side
error The return value of the upload error
size 2045 The actual size of the file

The error in the above array will return different constant values, as follows:
UPLOAD_ERR_OK No error occurred and the file was uploaded successfully
UPLOAD_ERR_INI_SIZE The file size exceeded the value of the upload_max_filesize option in PHP.INI
UPLOAD_ERR_FORM_SIZE The size of the uploaded file exceeded the MAX_FILE_SIZE option value in the HTML form. You can check the form $FILES ['up_file']['size'] in the program to process
UPLOAD_ERR_PARTIAL Only part of the file was uploaded
UPLOAD_ERR_NO_FILE The user did not provide any file upload
Specific example of post-upload processing:



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The code is as follows: if(!move_uploaded_file($_FILES['f']['tmp_name']," uploads/".$_FILES['f']['name'].".jpg")){ echo "error";

}

Function:
move_uploaded_file moves the uploaded temporary file to the specified directory
Example:

move_uploaded_file('temporary file name', 'specified file path')

is_uploaded_file determines whether it is a file uploaded through http Post
Example:



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The code is as follows: if(!is_uploaded_file($_FILES['f'][' tmp_name'])){ echo 'illegal';

}

3. Related parameters

Parameters in php.ini designed for PHP upload:
file_uploads Whether to allow file uploading, default ON

upload_tmp_dir Temporary directory to prevent uploading files, if not specified, the system default location is used

upload_max_filesize The maximum size of allowed uploaded files, the default is 2M

post_max_size controls the use of POST method for a form submission The maximum amount of data that PHP can accept. If you want to use PHP files to upload, this value should be changed to be larger than upload_max_filesize

max_input_time is the time to receive data through POST/GET/PUT in seconds. limit.

memory_limit In order to avoid running scripts from using a large amount of system memory, PHP allows defining memory usage limits. Set this parameter to specify the maximum memory capacity that a single script program can use, which should be appropriately larger than the post_max_size value.

max_execution_time is used to set the time that PHP waits for the script to be executed before forcibly terminating the script, in seconds. This second option can limit infinite loop scripts, but this feature can also cause the operation to fail when there is a long period of legitimate activity (such as uploading a large file). In this case, you must consider increasing this variable.

4. Consider uploading multiple files
You can easily upload multiple files by using the $_FILES array. The $_FILES array can obtain all the file field contents in the client form, thereby obtaining all files uploaded in the same form.

5. Break through the upload memory limit

Method 1:
Modify the memory_limit value in php.ini to a larger value, such as 64M
Method Two:
Use the Apache Rewrite method to dynamically modify the value of memory_limit. First create a .htaccess file and save it in the current directory of the file upload program. The code is as follows:
php_value memory_limit 100M
php_value post_max_size 30M
php_value upload_max_filesize 30M
php_value max_execution_time 300
php_value max_input_tim 300
php_value display_errors On

http://www.bkjia.com/PHPjc/321666.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/321666.htmlTechArticle1. The form part allows users to upload files. An upload attribute must be added to the declaration of the HTML form: enctype = 'multipart/form-data' The method of the form must be the POST form option MAX_FI...