How can I represent URL (possibly including query string) as a filename in Java without obscuring the original URL?

Is there any real way to represent a URL (which more than likely will also have a query string) as a filename in Java without obscuring the original URL completely?

My first approach was to simply escape invalid characters with arbitrary replacements (for example, replacing "/" with "_", etc). The problem is, as in the example of replacing with underscores is that a URL such as "app/my_app" would become "app_my_app" thus obscuring the original URL completely. I have also attempted to encode all th开发者_运维知识库e special characters, however again, seeing crazy %3e %20 etc is really not clear.

Thank you for any suggestions.

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Well, you should know what you want here, exactly. Keep in mind that the restrictions on file names vary between systems. On a Unix system you probably only need to escape the virgule somehow, whereas on Windows you need to take care of the colon and the question mark as well.

I guess, the safest thing would be to encode anything that could potentially clash (everything non-alphanumeric would be a good candidate, although you migth adapt this to the platform) with percent-encoding. It's still somewhat readable and you're guaranteed to get the original URL back.

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Why? URL-encoding is already defined in an RFC: there's not much point in reinventing it. Basically you must have an escape character such as %, otherwise you can't tell whether a character represents itself or an escape. E.g. in your example app_my_app could represent app/my/app. You therefore also need a double-escape convention so you can represent the escape character itself. It is not simple.