我可以硬编码`file：//`uri前缀吗？

Question

I was wondering if I can hardcore the file:// prefix into one of my functions in android.

The function is supposed to determine whether or not the given link points to an external resource on the web, or an internal resource inside the phone itself

public Uri generate_image_uri(String link)
{
    // link can be "1DCHiI2.jpg"
    // link can be "file://smiley_face.jpg"

    if (!link.startsWith("file://")
       return Uri.parse("https://i.imgur.com/" + link);
    else
       return Uri.parse(link);
}

Is this advisable? Or is there a more "fault tolerant" way of getting file:// ? maybe some function like getProperFilePrefixForThisAndroidVersion(); ?

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In order to clarify my question:

given the following code

(new File(getFilesDir(), "hello_world.jpg")).toString();

Is it safe to assume within reasonable probability that the resulting string will always start with file:// in all current and future Android versions?

Answer 1

Given:

 (new File(getFilesDir(), "hello_world.jpg")).toString(); 

is it safe to assume within reasonable probability that the resulting string will always start with file:// in all current and future Android versions?

No.

According to the javadoc for File on Android, File.toString returns:

"... the pathname string of this abstract pathname. This is just the string returned by the getPath() method."

Not a "file://" URL.

If you want to get a properly formed "file://" URL, do this:

 new File(...).toURI().toString()

Now, technically the protocol for a URL (ie "file") is case insensitive:

• Is the protocol name in URLs case sensitive?

Which means that "FILE://" or "File://" etc are technically valid alternatives.

However, the probability that above expression would ever emit anything other than the lower-case form of the protocol is (um) vanishingly small ¹ .

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^{1 - It would entail monumentally stupid decision making by a number of people. And they are NOT stupid people.}