Pass a local file in to URL in Java

Question

How do I create a new URL object using a local file, for the purpose of unit tests?

score 326 · Accepted Answer · edited Apr 16 '12 at 11:47

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new File(path).toURI().toURL();

edited Apr 16 '12 at 11:47

answered May 23 '11 at 14:22

jarnbjo

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For java 7+: Paths.get("path","to","stuff").toUri().toURL() – Ajax Nov 19 '15 at 00:32

Aleksandr Dubinsky · Answer 2 · 2021-11-19T09:11:19.550

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Using Java 11:

Path.of(string).toUri();

Using Java 7:

Paths.get(string).toUri();

To convert to the old-school URL class (why?), add .toURL(). Note there is a difference in the string output. The modern URI::toString begins with file:/// (the traditional URL syntax) while the nearly-deprecated URL::toString with file:/ (the modern URI syntax). Weird

edited Nov 19 '21 at 09:11

answered Jan 30 '14 at 16:16

Aleksandr Dubinsky

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"...a URI begins with file:/// but a URL with file:/ ..." Is that the case for both Windows and Linux? – ptntialunrlsd Jul 13 '15 at 09:19
@ptntialunrlsd That is a good question. I haven't checked, but I would guess yes. – Aleksandr Dubinsky Jul 13 '15 at 15:26
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No. An URL is just a special case of an URI. A file URI starts with "file://" and then lists the host (generally omitted), followed by "/" and the path "foo/bar" (generally meant to be read as an absolute path). Thus "file:///foo/var". An URI that looks like "file:/foo/bar" is incorrect. See also: [file URI scheme](https://en.wikipedia.org/wiki/File_URI_scheme) – David Tonhofer Sep 02 '15 at 14:00
@DavidTonhofer Thank you for the explanation of URIs, but that doesn't answer **ptntialunrlsd**'s question. What does '...toURL().toString()' produce on Linux? Also, I've reverted your edits because they made my answer more wordy without changing the meaning. – Aleksandr Dubinsky Sep 05 '15 at 17:16
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@AleksandrDubinsky It's best to leave pointers to the Oracle javadoc in though.. easier to click through to `java.nio.file.Paths`. Also, please be sure to make clear that you mean the _implementations_ in "URI vs URL". Anway `java.net.URL.toString()` produces the same thing on Unix, as it must. It only displays one "/" which is _very wrong_ (see [file URI scheme](https://en.wikipedia.org/wiki/File_URI_scheme)). I guess this is in Java because of reasons, better use `java.net.URI`. It correctly generates "file://[host]/" on a call to `.toString()`. – David Tonhofer Sep 05 '15 at 21:20
@DavidTonhofer Actually, URIs (RFC 3986, RFC 8089) allow the single-slash `file:/path` form, but URLs (RFC 1738) don't. – Aleksandr Dubinsky Nov 19 '21 at 07:48

score 43 · Answer 3 · answered May 23 '11 at 14:22

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new File("path_to_file").toURI().toURL();

answered May 23 '11 at 14:22

Ted Hopp

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score 23 · Answer 4 · answered May 23 '11 at 14:21

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new URL("file:///your/file/here")

answered May 23 '11 at 14:21

Alex

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where `/your/file/here` is an absolute path to a file on Unix/Linux. On Windows it would be different I think. – Robin Green May 23 '11 at 14:23
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That's not very clever, since you have to handle the escaping of characters which are not allowed in URLs yourself. On Windows (and potentially other operating systems), you also have to modify the path separator from the native path to the file. – jarnbjo May 23 '11 at 14:25
`new URL("file:my.properties");` – weberjn Oct 04 '17 at 14:03
While this is correct, it is not portable as it depends on absolute paths. – mazunki May 02 '20 at 14:59
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On Windows the following worked for me: `file:///C:\\file.zip` – Pawel Gorczynski Apr 15 '21 at 08:36

score 10 · Answer 5 · answered May 23 '11 at 14:23

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File myFile=new File("/tmp/myfile");
URL myUrl = myFile.toURI().toURL();

answered May 23 '11 at 14:23

Sean Patrick Floyd

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score 5 · Answer 6 · answered May 23 '11 at 14:23

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have a look here for the full syntax: http://en.wikipedia.org/wiki/File_URI_scheme for unix-like systems it will be as @Alex said file:///your/file/here whereas for Windows systems would be file:///c|/path/to/file

answered May 23 '11 at 14:23

Liv

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Don't do that manually. `File.toURI().toURL()`is the way to go – Sean Patrick Floyd May 23 '11 at 14:25
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@SeanPatrickFloyd sometimes you don't have a choice, like when it is in a `.properties` file. – Sled Jan 30 '14 at 19:24
@ArtB I don't see how that makes a difference – Sean Patrick Floyd Jan 31 '14 at 08:04
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@SeanPatrickFloyd, this question/answer comes up when you search for `java file url`, which in my case means that I was searching for the format of a `file://` URL, in Java, for use in a `.properties` file, or to type in manually, etc. – daveloyall Apr 28 '15 at 21:40
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@SeanPatrickFloyd sometimes you don't have access to the source code, just to the property, and `file://` is unfortunately necessary. Being system dependent is not such a huge issue since it's a mutable property. – vikingsteve Mar 20 '17 at 11:57

score 4 · Answer 7 · answered May 22 '12 at 18:32

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You can also use

[AnyClass].class.getResource(filePath)

answered May 22 '12 at 18:32

xMichal

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but only if that file exists within the classpath – aepurniet Feb 06 '14 at 21:20
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If the "filePath" can be found in a jar, the resulting URL is like `jar:file:/home/user/a/b/c/foo.jar!/com/example/stuff/config.txt`. – David Tonhofer Sep 02 '15 at 14:39

score 0 · Answer 8 · answered Feb 08 '21 at 15:11

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I tried it with Java on Linux. The following possibilities are OK:

file:///home/userId/aaaa.html
file:/home/userId/aaaa.html
file:aaaa.html  (if current directory is /home/userId)

not working is:

file://aaaa.html

answered Feb 08 '21 at 15:11

SzB

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Pass a local file in to URL in Java

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