How to Read file from a shared location Windows? (Java)

Question

Is there a way to read a file from a network shared location on windows?

Let's say for instance I've this simple code that reads a text file called readMe.txt from the Addons folder.

import java.io.File;

class Sample{

    public static void main(String[] ar){
        File file = new File("Addons/ReadMe.txt");
        System.out.println(file.getAbsolutePath());
      //followed by printing the contents of file   
    }
}

And I execute this file using a windows batch runme.bat that has

java Sample
PAUSE

The bat runs and executes the above class only when I place the Addons folder with ReadMe.txt, Sample.class, runme.bat file in my local drive.

When it is placed in a network shared location with UNC path like \\name\Shared

In such a scenario, the bat file typically starts the base from C:\Windows and throws a classNotFoundException. I can rather map the shared drive to a *Z:* drive or whatever but I do not want to do it.

I want the code to programatically detect and retrieve the content of Readme.txt in Addons folder irrespective of whether it is being executed on a local drive or on a shared drive. Is there a way to achieve this? Please help..

Thanks

Veekay

Answer 1

When using a file path in Java, make sure to escape all \ correctly when giving the full path name.

For example, if the file is on PC with IP (10.10.10.123) on a Shared folder called Addons then the full path will be:

File f = new File ("\\\\10.10.10.123\\Addons\\readme.txt");

Other than the full path, your code is throwing a ClassNotFound because you JAVA-CLASSPATH is not set properly.

Answer 2

In your bat file %~dp0 expands to the location of the bat file. You need that in your classpath so that java can find the class, though I don't know if it will choke on UNC path. For example:

@echo off
echo %~dp0

would output

\\host\share\dir

EDIT: %dp0 will not work if there are spaces. This is what you need in your bat file:

@echo off
set p=%~dps0
echo %p%
java -classpath %p%\jarname classname
pause

Answer 3

Two ways of doing.

1) Map the shared path to a local drive.

2) Else hard code the server path in new File('') as mentioned by Medopal.

Something like new File("").getAbsolutePath() might help me get the base Folder when executed on a local system. Likewise there is no such way to programmatically find out the working base when executed on a shared location.