How do I create a new URL object using a local file, for the purpose of unit tests?
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9 Answers
NIO.2 in modern Java
Java I/O improved dramatically with the arrival of NIO and NIO.2. See guide by Oracle. See Wikipedia.
Using Path.of in Java 11 and later:
Path.of(string).toUri();
Or in earlier Java use Paths.get.
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 🤷
answered Jan 30, 2014 at 16:16
Aleksandr Dubinsky
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6 Comments
ptntialunrlsd
"...a URI begins with file:/// but a URL with file:/ ..." Is that the case for both Windows and Linux?
Aleksandr Dubinsky
@ptntialunrlsd That is a good question. I haven't checked, but I would guess yes.
David Tonhofer
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
Aleksandr Dubinsky
@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.
David Tonhofer
@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). I guess this is in Java because of reasons, better use java.net.URI. It correctly generates "file://[host]/" on a call to .toString(). |
new File("path_to_file").toURI().toURL();
Comments
new URL("file:///your/file/here")
4 Comments
Robin Green
where
/your/file/here is an absolute path to a file on Unix/Linux. On Windows it would be different I think.
jarnbjo
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.
mazunki
While this is correct, it is not portable as it depends on absolute paths.
Pawel Gorczynski
On Windows the following worked for me:
file:///C:\\file.zipFile myFile=new File("/tmp/myfile");
URL myUrl = myFile.toURI().toURL();
answered May 23, 2011 at 14:23
Sean Patrick Floyd
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Comments
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
5 Comments
Sean Patrick Floyd
Don't do that manually.
File.toURI().toURL()is the way to go
Sled
@SeanPatrickFloyd sometimes you don't have a choice, like when it is in a
.properties file.Sean Patrick Floyd
@ArtB I don't see how that makes a difference
daveloyall
@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.
vikingsteve
@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.You can also use
[AnyClass].class.getResource(filePath)
2 Comments
aepurniet
but only if that file exists within the classpath
David Tonhofer
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.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
Comments
For Windows: You have use in this way if file is in some drive:
eg.:
Actual link:
"C:\Users\er2\Downloads\Designer3.png"
Converted link:
"file:/C:/Users/er2/Downloads/Designer3.png"
