Regex to find a string anywhere

[Derv McDermott]

Hi,

Apologies if this is not worded well..

Basically I have this line in a servlet

FileInputStream flinp = new FileInputStream("C:\\xampp\\img\\"+empid+".jpg");

where empid is a string.

So currently I am getting files with the empid as the name, but I need to get files that have the empid ANYWHERE in the name.. so for example if my empid is 2500, I need to get the file if its called anything like -
2500_Amy
Amy_2500
Amy2500
2500Amy

Can anyone help with this? Is it regex I need to use and if so what do I write? Thanks

[Campbell Ritchie]

Don't know much about regexes, but what about this?

.*2500.*

Remember that the full stop is a metacharacter for anything except line ends.

[Knute Snortum]

Well, if it's as simple as finding a String in a String, what about using String#indexOf(String)?  Anything that doesn't return -1 is a match.

If you need something more complex than that, you could use Matcher#find().

[Junilu Lacar]

or use String.contains(substr)

[Stephan van Hulst]

I think you guys have the requirements mixed up. This is not about finding a string, this is about finding a file.

The Files utility class contains a method that allows you to iterate children of a specified directory while filtering them using a glob. Globs are like simple regular expressions that target file paths specifically.

var glob = String.format("*%s*.[jJ][pP][gG]", escapeSpecialGlobCharacters(employeeId));

for (var imagePath: Files.newDirectoryStream(imageDirectoryPath, glob)) {
  // use the image path
}

If you can guarantee that the employee ID doesn't contain special glob characters, you can use it directly, without calling escapeSpecialGlobCharacters(). Otherwise you can use the following implementation:

private static String escapeSpecialGlobCharacters(String s) {
  return s.replaceAll("[*?{}\\[\\]\\\\]", "\\\\$0");
}

This method escapes the special characters * ? { } [ ] \ with a backslash.

[Stephan van Hulst]

I question the wisdom of accessing files on the server's file system like that though.

Are you sure that the application will always run on the same machine as XAMPP, with XAMPP being installed in that exact location, with that exact directory structure? If the images are hosted by XAMPP, isn't it better to retrieve them using a HTTP request to localhost?

[Derv McDermott]

Yeah so I've now realised that you can't use regex directly with FileInputStream..

Stephan van Hulst thank you but I am a bit confused on where I'd put your given code in my servlet.

Also it is not actually XAMPP that will be used that was just for purpose of an example, but the photos will actually be in a folder on a Wildfly server (which my app will be hosted on) and they will stay in that folder.. if that makes my question any different? Is there a better way you think I could be reading the files to begin with?

Thanks

[Stephan van Hulst]

Derv McDermott wrote:Stephan van Hulst thank you but I am a bit confused on where I'd put your given code in my servlet.

In the same place where you use your existing code.

Is there a better way you think I could be reading the files to begin with?

Normally I wouldn't use a file system to store dynamic resources in the first place, but a database instead. You can use the BLOB data type.

Are the images shared between applications? Will they always be in a fixed location relative to your application? Can you guarantee this for all customers where the application will be installed?