Java Path for Specific FileSystem

Question

Reading the documentation on Path and other places it's obvious to me that it always takes the file system the VM is running on. However, I want to make it clear to Java that I want to have Unix-paths.

The reason is that I'm exporting paths as JSON via Jackson and there using toString() in a serializer returns different results for different VMs. In simple terms I want to get this even if I'm developing on a Windows machine:

{"path":"/tmp"}

My serializer looks like this:

public class PathSerializer extends JsonSerializer<Path> {

  @Override
  public void serialize(Path path, JsonGenerator jsonGenerator, SerializerProvider provider) throws IOException, JsonProcessingException {
    jsonGenerator.writeString(path.toString());
  }

}

To solve it for Windows I could do this of course:

public class PathSerializer extends JsonSerializer<Path> {

  @Override
  public void serialize(Path path, JsonGenerator jsonGenerator, SerializerProvider provider) throws IOException, JsonProcessingException {
    jsonGenerator.writeString(path.toString().replace('\\', '/'));
  }

}

But, that's not independent of the file system. I mean I know what target system I have and I don't want to cover all source systems here.

How do I do that? I mean the last resort of course is to use String instead of Path, but that's kind of lame IMHO.

what value contains your path variable ?? is it like that ?? eg:- foldername\\foldername\\filename — Vikrant Kashyap
– Vikrant Kashyap, Commented Mar 18, 2016 at 8:44
@VikrantKashyap An absolute path. Currently the JSON would look like {"path":"\\tmp"} — sjngm
– sjngm, Commented Mar 18, 2016 at 8:53
your questions is valid . If your production system is deployed over 'linux` and User System is windows based then it will raise an error — Vikrant Kashyap
– Vikrant Kashyap, Commented Mar 18, 2016 at 8:58

Ahmed H. Saab · Accepted Answer · 2016-03-18 08:57:27Z

1

This will work on all platforms:

@Override
public void serialize(Path path, JsonGenerator jsonGenerator, SerializerProvider provider) throws IOException, JsonProcessingException
{
   jsonGenerator.writeString(path.toString().replace(File.separator, "/"));
}

With the Java libraries for dealing with files, you can safely use / (slash, not backslash) on all platforms. The library code handles translating things into platform-specific paths internally. That being said no matter what OS will later on read the path will be able to construct it correctly.

answered Mar 18, 2016 at 8:57

Ahmed H. Saab

4135 silver badges15 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

sjngm Over a year ago

I think this is the closest I can get to a "path generator for a different file system".

Ludovic Frérot · Accepted Answer · 2016-03-18 09:28:13Z

1

The trick is to use the URI in between..

// At the begining you have the input parameter with tmp path in it
// so same as:
Path path= new File("/tmp").toPath();
// System.out.println(path.toString()) 
// -> "\tmp" under windows
URI theTmpFolderURI = path.toUri();
// System.out.println(theTmpFolderURI.toString()) 
// -> "file:///C:/tmp" under windows and 
// -> "file://tmp/" under xNIX

Back to a Path and then a file the result is environment dependent under windows you got

Paths.get(theTmpFolderURI).toFile().getAbsolutePath();
// -> C:\tmp

Same as :

Paths.get(theTmpFolderURI).toAbsolutePath().toString();
// -> C:\tmp

So the code will be something like:

String fromString = Paths.get(path.toUri()).toAbsolutePath().toString(); 
jsonGenerator.writeString(fromString);

and the resulting JSON will be

"C:\\tmp"

edited Mar 18, 2016 at 9:28

answered Mar 18, 2016 at 8:57

Ludovic Frérot

6054 silver badges9 bronze badges

5 Comments

sjngm Over a year ago

Where does it get rid of the backslash?

Ludovic Frérot Over a year ago

For the communication between systems always uses the URI notation. That's the purpose of the standard obviously :) Internally (server side) the code will adapt the the current environment automatically and transform the URI to specific filesystem resource identifiers at runtime. The double backslash in the JSON is mandatory for the JSON to be VALID....

Ludovic Frérot Over a year ago

If you need to force the filesystem to a specific environment I recomment using the Apache Commons IO project's tooling like this method for windows style conversion or this other for the unix style.

sjngm Over a year ago

No, that's not what I want, I think you misunderstand the question. I don't need full URIs, just the path and I don't need any backslashes anywhere.

Ludovic Frérot Over a year ago

Have a look to the Apache Commons IO FilenameUtils. There is some nice windows to Unix and reverse conversation tools. commons.apache.org/proper/commons-io/javadocs/api-1.4/org/…

Collectives™ on Stack Overflow

Java Path for Specific FileSystem

2 Answers 2

1 Comment

5 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

5 Comments

Your Answer

Sign up or log in

Post as a guest

Related