Ant path style patterns

java

file-system

pattern-matching

wildcards

byAnton Shumikhin·Jan 15, 2025

Let's match strings with Ant-style path patterns using Java's AntPathMatcher. Here's a simple illustration:

import org.springframework.util.AntPathMatcher;

AntPathMatcher matcher = new AntPathMatcher();
boolean result = matcher.match("*.jpg", "photo.jpg");  // returns true because photo.jpg is obviously a JPG!

With the match method, we're checking whether "photo.jpg" aligns with the *.jpg pattern, denoting it as a JPG image. This could be a cool way when handling tasks such as file filtering or path structure validation.

Parsing wildcard characters

In the realm of Ant path patterns, wildcards are your best friends, helping you match strings with style:

*, the globetrotter, matches zero or more characters within a single path segment.
**, the freewheeler, matches any number of directories across path segments.
?, the finicky one, matches just one character.

Let's put these wild ones to action with some examples:

Single wildcard at its best

Imagine you're rummaging through a directory for all .txt files:

Pattern: '*.txt' will match 'notes.txt', 'chapter1.txt', but not 'novel.pdf'. That's a bit too obvious, isn't it?

All-around directory search

When you're on a treasure hunt for a particular file, not minding its family tree (directory nesting):

Pattern: '**/README.md' will match 'README.md' in any directory, even if it's hiding under seven sub-folders!

One character precision

Those nerve-racking moments when you need to be so precise, down to a single character:

Pattern: 'data_?.csv' will call out to 'data_1.csv', 'data_2.csv', but will snub 'data_10.csv'. Tough love!

Juggling with path variables and regex

Add some flair with variables and regular expressions in these patterns to grab specific path segments like a pro:

boolean result = matcher.match("web/{section:[a-z]+}/{page}.html", "web/news/article.html");
// Here {section:[a-z]+} snags any lowercase word as a 'section', and {page} triumphantly captures 'article'. Magic!

Practical example scenarios

File extension rendezvous

Let's say you need to round up all JavaScript files in a static folder that follow a particular naming convention:

Pattern: 'static/*.min.js' will eyeball 'static/jquery.min.js', but will overlook 'static/jquery.js'. Selective vision!

Diving into directory layers

Perhaps you're trying to match a pattern with varying intermediate directories:

Pattern: 'images/**/thumbnail/*.jpg' will spot 'images/events/2021/thumbnail/pic.jpg', no matter how deep it's buried.

Steer clear of common pitfalls

Deciphering wildcards

Getting the scope of the wildcard mix-up is surprisingly easy. Here's a tip: * sticks to its directory, while ** roams freely across directories.

The importance of path separators

Mind your backslash (/) and your forward slash ()! The file separator changes with operating systems and affects pattern matches.

Stay platform-agnostic

Java file system operations play nice on some playgrounds than others. Make your patterns platform-independent to score points.

Power-up tips and tricks

Harnessing Java's NIO API

Did you know Java NIO's PathMatcher can soup-up your file system wizardry even further?

The genius of Spring's AntPathMatcher

Fancy a spa treatment with Spring? Dabble with AntPathMatcher to flex your pattern matching muscles at a whole new level.

Diving into comprehensive resources

For the insatiable coder thirsting for knowledge, shake hands with the Oracle (official documentation) and theological tomes like "Ant in Action" for deep dives into advanced pattern matching.

explain-codes / Java / Ant path style patterns

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