TestJunctionWithJavaNIO

TestJunction.java

package test;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Arrays;
import java.util.List;

/*
 *
 * prepare the directory from cmd with admin rights
 *
 * mkdir c:\temp\a
 * cd /d c:\temp
 * mklink /j junction_to_a a
 * mklink /d symlink_to_a a
 * 
 * Hardlinks only on files -> http://msdn.microsoft.com/en-us/library/aa365006%28VS.85%29.aspx
 * echo 1 > b
 * mklink /h hardlink_to_b b
 *
 */
public class TestJunction {

/*
 *  results on my machine
 *	
 *	# test for junction
 *              a -> isJunction = false
 *  junction_to_a -> isJunction = true
 *   symlink_to_a -> isJunction = true
 *  hardlink_to_b -> isJunction = false
 *
 * # test for symlink
 *             a -> isSymbolicLink = false
 * junction_to_a -> isSymbolicLink = false
 *  symlink_to_a -> isSymbolicLink = true
 * hardlink_to_b -> isSymbolicLink = false
 *
 * # test for regular file
 *             a -> isRegularFile = false
 * junction_to_a -> isRegularFile = false
 *  symlink_to_a -> isRegularFile = false
 * hardlink_to_b -> isRegularFile = true
 */

public static void main(String[] args) {

        String dir = "c:/temp";
        
        List<String> fileNames = Arrays.asList("a","junction_to_a","symlink_to_a", "hardlink_to_b");
        
        System.out.println("\n# test for junction");
        fileNames.forEach(file -> {
            System.out.format("%15s -> isJunction = %s\n", file, isJunction(Paths.get(dir, file)));
        });
        
        System.out.println("\n# test for symlink");
        fileNames.forEach(file -> {
            System.out.format("%15s -> isSymbolicLink = %s\n", file, Files.isSymbolicLink(Paths.get(dir, file)));
        });

        System.out.println("\n# test for regular file");
        fileNames.forEach(file -> {
            System.out.format("%15s -> isRegularFile = %s\n", file, Files.isRegularFile(Paths.get(dir, file)));
        });
    }

    /**
     * returns true if the Path is a Windows Junction
     */
    private static boolean isJunction(Path p) {
        boolean isJunction = false;
        try {
            isJunction = (p.compareTo(p.toRealPath()) != 0);
        }
        catch (IOException e) {
            e.printStackTrace(); // TODO: handleMeProperly
        }
        return isJunction;
    }
}