Joomla 2.5：GD库-如何命名文件以避免冲突

Question

I'm writing a component for Joomla 2.5 that generates a graph using the PHP GD Library depending on the users input.

What name should I give the image file to avoid conflict when multiple users are using the component.

Answer 1

you can generate random name with help of eg date and php hash function: http://www.php.net/manual/en/function.hash.php

So the name will be unique.

Or, depends on used feature in your component, you can somehow add the user name to the image name. It depends of the function of the component and on my factors (if there will be only one image per user, or per some other feature, etc.)

Jan

Answer 2

In my opinion you have two way. The first is save the image with prefix like this

scotttiger-img12321323.jpg

where scotttiger is the username and 12321323 is the user input. Another way is to use different folder for every user

scotttiger/1231321.jpg

But if You don't have the user logged in and doesn't know the username, do a simple check with isfile ( http://it1.php.net/is_file ) function and set incremental name. eg:

$wrote = false;
$prog = 0;
$filename="img-{$user_input}-{$prog}.jpg";
while(isfile($filename)) {
   $prog++;
   $filename="img-{$user_input}-{$prog}.jpg";
}
write_file($filename);

So you have the first time img-input-1.jpg the second once img-input-2.jpg and so on. With this solution You doesn't have duplicates or conflict.

You can improve performance with this solution:

$wrote = false;
$prog = md5(time());
$filename="img-{$user_input}-{$prog}.jpg";
while(isfile($filename)) {
   $prog = md5(time());
   $filename="img-{$user_input}-{$prog}.jpg";
}
write_file($filename);