public static void main(String[] args) {
File root = new File("z:/a/b/c/d");
File t1 = new File("z:/a/b/e/f");
File t2 = new File("c:/t/r");
File t3 = new File("z:/a/b/c/d/i/m");
File t4 = new File("z:/a/b/c/d");
System.out.println("Rel root, t1: " + makePathRelativeIfPossible(root, t1));
System.out.println("Rel root, t2: " + makePathRelativeIfPossible(root, t2));
System.out.println("Rel root, t3: " + makePathRelativeIfPossible(root, t3));
System.out.println("Rel root, t4: " + makePathRelativeIfPossible(root, t4));
File f1 = new File("f:\\a\\b");
File f2 = new File("f:\\a\\c");
File f3 = new File(f1, f2.toString());
System.out.println("f3 = " + f3.toString());
}
// root : z:/a/b/c/d
// t1: z:/a/b/e/f
// t2: c:/t/r
// t3: z:/a/b/c/d/i/m
// t4: z:/a/b/c/d
public static File makePathRelativeIfPossible(File root, File f) {
if (f.toString().indexOf("${") >= 0) return f;
File orgfile = f;
try {
if (f.isAbsolute() == false) {
f = new File(root, f.toString());
}
f = f.getCanonicalFile();
f = f.getAbsoluteFile();
root = root.getCanonicalFile();
root = root.getAbsoluteFile();
} catch (IOException iox) {
iox.printStackTrace();
System.out.println("Failed, returning " + orgfile);
return orgfile;
}
Vector rootvec = new Vector();
Vector targetvec = new Vector();
File cur;
cur = root;
while (cur != null) {
String n = cur.getName();
// lame hack, because getName() returns "" when the file is a drive (like c: or z:)
if (n.equals("")) n = cur.getAbsolutePath();
rootvec.add(0, n);
cur = cur.getParentFile();
}
cur = f;
while (cur != null) {
String n = cur.getName();
if (n.equals("")) n = cur.getAbsolutePath();
targetvec.add(0, n);
cur = cur.getParentFile();
}
// find the lowest common path
int cursor = 0;
while ((cursor < rootvec.size()) && (cursor < targetvec.size())) {
if (rootvec.elementAt(cursor).equals(targetvec.elementAt(cursor)) == false) break;
cursor++;
}
if (cursor == 0) return f;
if ((cursor == rootvec.size()) && (cursor == targetvec.size())) return new File(".");
StringBuffer buffer = new StringBuffer();
for (int i = cursor; i < rootvec.size(); i++) {
buffer.append("../");
}
for (int i = cursor; i < targetvec.size(); i++) {
buffer.append(targetvec.elementAt(i).toString());
buffer.append("/");
}
return new File(buffer.toString());
}