How to find out if string has already been URL encoded?

Question

How could I check if string has already been encoded?

For example, if I encode TEST==, I get TEST%3D%3D. If I again encode last string, I

Answer 1

Using Spring UriComponentsBuilder:

import java.net.URI;
import org.springframework.web.util.UriComponentsBuilder;

private URI getProperlyEncodedUri(String uriString) {
    try {
        return URI.create(uriString);
    } catch (IllegalArgumentException e) {
        return UriComponentsBuilder.fromUriString(uriString).build().toUri();
    }
}