Comment construire un chemin relatif en Java à partir de deux chemins absolus (ou URL)?
Étant donné deux chemins absolus, par exemple.
/var/data/stuff/xyz.dat
/var/data
Comment créer un chemin relatif qui utilise le deuxième chemin comme base? Dans l'exemple ci-dessus, le résultat devrait être: ./stuff/xyz.dat
C'est un petit rond point, mais pourquoi ne pas utiliser l'URI? Il a une méthode relativiser qui fait toutes les vérifications nécessaires pour vous.
String path = "/var/data/stuff/xyz.dat";
String base = "/var/data";
String relative = new File(base).toURI().relativize(new File(path).toURI()).getPath();
// relative == "stuff/xyz.dat"
Notez que pour le chemin du fichier, il y a Java.nio.file.Path#relativize depuis Java 1.7, comme indiqué par @Jirka Meluzin in l'autre réponse .
Depuis Java 7, vous pouvez utiliser la méthode relativize :
import Java.nio.file.Path;
import Java.nio.file.Paths;
public class Test {
public static void main(String[] args) {
Path pathAbsolute = Paths.get("/var/data/stuff/xyz.dat");
Path pathBase = Paths.get("/var/data");
Path pathRelative = pathBase.relativize(pathAbsolute);
System.out.println(pathRelative);
}
}
Sortie:
stuff/xyz.dat
Au moment de la rédaction de cet article (juin 2010), cette solution était la seule à réussir mes tests. Je ne peux pas garantir que cette solution soit exempte de bugs, mais elle réussit les cas de test inclus. La méthode et les tests que j'ai écrits dépendent de la FilenameUtils class de Apache commons IO .
La solution a été testée avec Java 1.4. Si vous utilisez Java 1.5 (ou supérieur), vous devriez envisager de remplacer StringBuffer par StringBuilder (si vous utilisez toujours Java 1.4, vous devriez plutôt envisager un changement d'employeur).
import Java.io.File;
import Java.util.regex.Pattern;
import org.Apache.commons.io.FilenameUtils;
public class ResourceUtils {
/**
* Get the relative path from one file to another, specifying the directory separator.
* If one of the provided resources does not exist, it is assumed to be a file unless it ends with '/' or
* '\'.
*
* @param targetPath targetPath is calculated to this file
* @param basePath basePath is calculated from this file
* @param pathSeparator directory separator. The platform default is not assumed so that we can test Unix behaviour when running on Windows (for example)
* @return
*/
public static String getRelativePath(String targetPath, String basePath, String pathSeparator) {
// Normalize the paths
String normalizedTargetPath = FilenameUtils.normalizeNoEndSeparator(targetPath);
String normalizedBasePath = FilenameUtils.normalizeNoEndSeparator(basePath);
// Undo the changes to the separators made by normalization
if (pathSeparator.equals("/")) {
normalizedTargetPath = FilenameUtils.separatorsToUnix(normalizedTargetPath);
normalizedBasePath = FilenameUtils.separatorsToUnix(normalizedBasePath);
} else if (pathSeparator.equals("\\")) {
normalizedTargetPath = FilenameUtils.separatorsToWindows(normalizedTargetPath);
normalizedBasePath = FilenameUtils.separatorsToWindows(normalizedBasePath);
} else {
throw new IllegalArgumentException("Unrecognised dir separator '" + pathSeparator + "'");
}
String[] base = normalizedBasePath.split(Pattern.quote(pathSeparator));
String[] target = normalizedTargetPath.split(Pattern.quote(pathSeparator));
// First get all the common elements. Store them as a string,
// and also count how many of them there are.
StringBuffer common = new StringBuffer();
int commonIndex = 0;
while (commonIndex < target.length && commonIndex < base.length
&& target[commonIndex].equals(base[commonIndex])) {
common.append(target[commonIndex] + pathSeparator);
commonIndex++;
}
if (commonIndex == 0) {
// No single common path element. This most
// likely indicates differing drive letters, like C: and D:.
// These paths cannot be relativized.
throw new PathResolutionException("No common path element found for '" + normalizedTargetPath + "' and '" + normalizedBasePath
+ "'");
}
// The number of directories we have to backtrack depends on whether the base is a file or a dir
// For example, the relative path from
//
// /foo/bar/baz/gg/ff to /foo/bar/baz
//
// ".." if ff is a file
// "../.." if ff is a directory
//
// The following is a heuristic to figure out if the base refers to a file or dir. It's not perfect, because
// the resource referred to by this path may not actually exist, but it's the best I can do
boolean baseIsFile = true;
File baseResource = new File(normalizedBasePath);
if (baseResource.exists()) {
baseIsFile = baseResource.isFile();
} else if (basePath.endsWith(pathSeparator)) {
baseIsFile = false;
}
StringBuffer relative = new StringBuffer();
if (base.length != commonIndex) {
int numDirsUp = baseIsFile ? base.length - commonIndex - 1 : base.length - commonIndex;
for (int i = 0; i < numDirsUp; i++) {
relative.append(".." + pathSeparator);
}
}
relative.append(normalizedTargetPath.substring(common.length()));
return relative.toString();
}
static class PathResolutionException extends RuntimeException {
PathResolutionException(String msg) {
super(msg);
}
}
}
Les cas de test que cela réussit sont
public void testGetRelativePathsUnix() {
assertEquals("stuff/xyz.dat", ResourceUtils.getRelativePath("/var/data/stuff/xyz.dat", "/var/data/", "/"));
assertEquals("../../b/c", ResourceUtils.getRelativePath("/a/b/c", "/a/x/y/", "/"));
assertEquals("../../b/c", ResourceUtils.getRelativePath("/m/n/o/a/b/c", "/m/n/o/a/x/y/", "/"));
}
public void testGetRelativePathFileToFile() {
String target = "C:\\Windows\\Boot\\Fonts\\chs_boot.ttf";
String base = "C:\\Windows\\Speech\\Common\\sapisvr.exe";
String relPath = ResourceUtils.getRelativePath(target, base, "\\");
assertEquals("..\\..\\Boot\\Fonts\\chs_boot.ttf", relPath);
}
public void testGetRelativePathDirectoryToFile() {
String target = "C:\\Windows\\Boot\\Fonts\\chs_boot.ttf";
String base = "C:\\Windows\\Speech\\Common\\";
String relPath = ResourceUtils.getRelativePath(target, base, "\\");
assertEquals("..\\..\\Boot\\Fonts\\chs_boot.ttf", relPath);
}
public void testGetRelativePathFileToDirectory() {
String target = "C:\\Windows\\Boot\\Fonts";
String base = "C:\\Windows\\Speech\\Common\\foo.txt";
String relPath = ResourceUtils.getRelativePath(target, base, "\\");
assertEquals("..\\..\\Boot\\Fonts", relPath);
}
public void testGetRelativePathDirectoryToDirectory() {
String target = "C:\\Windows\\Boot\\";
String base = "C:\\Windows\\Speech\\Common\\";
String expected = "..\\..\\Boot";
String relPath = ResourceUtils.getRelativePath(target, base, "\\");
assertEquals(expected, relPath);
}
public void testGetRelativePathDifferentDriveLetters() {
String target = "D:\\sources\\recovery\\RecEnv.exe";
String base = "C:\\Java\\workspace\\AcceptanceTests\\Standard test data\\geo\\";
try {
ResourceUtils.getRelativePath(target, base, "\\");
fail();
} catch (PathResolutionException ex) {
// expected exception
}
}
Lorsque vous utilisez Java.net.URI.relativize, vous devez être conscient du bogue Java: JDK-6226081 (l’URI doit pouvoir relativiser les chemins avec des racines partielles)
Pour le moment, la méthode
relativize()deURIne relativise les URI que lorsque l'un est le préfixe de l'autre.
Ce qui signifie essentiellement que Java.net.URI.relativize ne créera pas de ".." pour vous.
Le bug mentionné dans la réponse de Peter Peter Mueller est traité par URIUtils in Apache HttpComponents
public static URI resolve(URI baseURI,
String reference)
Résout une référence d'URI contre un URI de base. Contournement pour bug dans Java.net.URI ()
Dans Java 8 vous pouvez simplement faire (et contrairement à URI, il n’ya pas de bogue):
Path#relativize(Path)
Si vous savez que la deuxième chaîne fait partie de la première:
String s1 = "/var/data/stuff/xyz.dat";
String s2 = "/var/data";
String s3 = s1.substring(s2.length());
ou si vous voulez vraiment la période au début comme dans votre exemple:
String s3 = ".".concat(s1.substring(s2.length()));
La récursivité produit une solution plus petite. Cela lève une exception si le résultat est impossible (par exemple, un autre disque Windows) ou peu pratique (la racine n’est que le répertoire commun).
/**
* Computes the path for a file relative to a given base, or fails if the only shared
* directory is the root and the absolute form is better.
*
* @param base File that is the base for the result
* @param name File to be "relativized"
* @return the relative name
* @throws IOException if files have no common sub-directories, i.e. at best share the
* root prefix "/" or "C:\"
*/
public static String getRelativePath(File base, File name) throws IOException {
File parent = base.getParentFile();
if (parent == null) {
throw new IOException("No common directory");
}
String bpath = base.getCanonicalPath();
String fpath = name.getCanonicalPath();
if (fpath.startsWith(bpath)) {
return fpath.substring(bpath.length() + 1);
} else {
return (".." + File.separator + getRelativePath(parent, name));
}
}
Voici une solution autre bibliothèque libre:
Path sourceFile = Paths.get("some/common/path/example/a/b/c/f1.txt");
Path targetFile = Paths.get("some/common/path/example/d/e/f2.txt");
Path relativePath = sourceFile.relativize(targetFile);
System.out.println(relativePath);
Les sorties
..\..\..\..\d\e\f2.txt
[EDIT] en fait, il sort plus ..\parce que la source est un fichier et non un répertoire La solution correcte pour mon cas est:
Path sourceFile = Paths.get(new File("some/common/path/example/a/b/c/f1.txt").parent());
Path targetFile = Paths.get("some/common/path/example/d/e/f2.txt");
Path relativePath = sourceFile.relativize(targetFile);
System.out.println(relativePath);
Ma version est basée sur les versions de Matt et Steve :
/**
* Returns the path of one File relative to another.
*
* @param target the target directory
* @param base the base directory
* @return target's path relative to the base directory
* @throws IOException if an error occurs while resolving the files' canonical names
*/
public static File getRelativeFile(File target, File base) throws IOException
{
String[] baseComponents = base.getCanonicalPath().split(Pattern.quote(File.separator));
String[] targetComponents = target.getCanonicalPath().split(Pattern.quote(File.separator));
// skip common components
int index = 0;
for (; index < targetComponents.length && index < baseComponents.length; ++index)
{
if (!targetComponents[index].equals(baseComponents[index]))
break;
}
StringBuilder result = new StringBuilder();
if (index != baseComponents.length)
{
// backtrack to base directory
for (int i = index; i < baseComponents.length; ++i)
result.append(".." + File.separator);
}
for (; index < targetComponents.length; ++index)
result.append(targetComponents[index] + File.separator);
if (!target.getPath().endsWith("/") && !target.getPath().endsWith("\\"))
{
// remove final path separator
result.delete(result.length() - File.separator.length(), result.length());
}
return new File(result.toString());
}
La solution de Matt B indique le nombre de répertoires dans lesquels le retour en arrière est incorrect - ce doit être la longueur du chemin de base moins le nombre d'éléments de chemin communs, moins un (pour le dernier élément de chemin, qui est un nom de fichier ou un "" final généré par split). Il se trouve que cela fonctionne avec /a/b/c/ et /a/x/y/, mais remplacez les arguments par /m/n/o/a/b/c/ et /m/n/o/a/x/y/ et vous verrez le problème.
De plus, il a besoin d'un else break dans la première boucle for, sinon les noms de répertoires correspondants, tels que /a/b/c/d/ et /x/y/c/z, seront mal gérés. La variable c se trouve dans le même emplacement dans les deux tableaux, mais ne correspond pas.
Toutes ces solutions n'ont pas la capacité de gérer des chemins qui ne peuvent pas être relativisés les uns aux autres car elles ont des racines incompatibles, telles que C:\foo\bar et D:\baz\quux. Probablement seulement un problème sur Windows, mais il convient de le noter.
J'ai passé beaucoup plus de temps que prévu sur ce sujet, mais ça va. En fait, j’avais besoin de ça pour le travail, alors merci à tous ceux qui sont intervenus, et je suis sûr que cette version sera corrigée aussi!
public static String getRelativePath(String targetPath, String basePath,
String pathSeparator) {
// We need the -1 argument to split to make sure we get a trailing
// "" token if the base ends in the path separator and is therefore
// a directory. We require directory paths to end in the path
// separator -- otherwise they are indistinguishable from files.
String[] base = basePath.split(Pattern.quote(pathSeparator), -1);
String[] target = targetPath.split(Pattern.quote(pathSeparator), 0);
// First get all the common elements. Store them as a string,
// and also count how many of them there are.
String common = "";
int commonIndex = 0;
for (int i = 0; i < target.length && i < base.length; i++) {
if (target[i].equals(base[i])) {
common += target[i] + pathSeparator;
commonIndex++;
}
else break;
}
if (commonIndex == 0)
{
// Whoops -- not even a single common path element. This most
// likely indicates differing drive letters, like C: and D:.
// These paths cannot be relativized. Return the target path.
return targetPath;
// This should never happen when all absolute paths
// begin with / as in *nix.
}
String relative = "";
if (base.length == commonIndex) {
// Comment this out if you prefer that a relative path not start with ./
//relative = "." + pathSeparator;
}
else {
int numDirsUp = base.length - commonIndex - 1;
// The number of directories we have to backtrack is the length of
// the base path MINUS the number of common path elements, minus
// one because the last element in the path isn't a directory.
for (int i = 1; i <= (numDirsUp); i++) {
relative += ".." + pathSeparator;
}
}
relative += targetPath.substring(common.length());
return relative;
}
Et voici des tests pour couvrir plusieurs cas:
public void testGetRelativePathsUnixy()
{
assertEquals("stuff/xyz.dat", FileUtils.getRelativePath(
"/var/data/stuff/xyz.dat", "/var/data/", "/"));
assertEquals("../../b/c", FileUtils.getRelativePath(
"/a/b/c", "/a/x/y/", "/"));
assertEquals("../../b/c", FileUtils.getRelativePath(
"/m/n/o/a/b/c", "/m/n/o/a/x/y/", "/"));
}
public void testGetRelativePathFileToFile()
{
String target = "C:\\Windows\\Boot\\Fonts\\chs_boot.ttf";
String base = "C:\\Windows\\Speech\\Common\\sapisvr.exe";
String relPath = FileUtils.getRelativePath(target, base, "\\");
assertEquals("..\\..\\..\\Boot\\Fonts\\chs_boot.ttf", relPath);
}
public void testGetRelativePathDirectoryToFile()
{
String target = "C:\\Windows\\Boot\\Fonts\\chs_boot.ttf";
String base = "C:\\Windows\\Speech\\Common";
String relPath = FileUtils.getRelativePath(target, base, "\\");
assertEquals("..\\..\\Boot\\Fonts\\chs_boot.ttf", relPath);
}
public void testGetRelativePathDifferentDriveLetters()
{
String target = "D:\\sources\\recovery\\RecEnv.exe";
String base = "C:\\Java\\workspace\\AcceptanceTests\\Standard test data\\geo\\";
// Should just return the target path because of the incompatible roots.
String relPath = FileUtils.getRelativePath(target, base, "\\");
assertEquals(target, relPath);
}
En fait, mon autre réponse ne fonctionnait pas si le chemin cible n'était pas un enfant du chemin de base.
Cela devrait marcher.
public class RelativePathFinder {
public static String getRelativePath(String targetPath, String basePath,
String pathSeparator) {
// find common path
String[] target = targetPath.split(pathSeparator);
String[] base = basePath.split(pathSeparator);
String common = "";
int commonIndex = 0;
for (int i = 0; i < target.length && i < base.length; i++) {
if (target[i].equals(base[i])) {
common += target[i] + pathSeparator;
commonIndex++;
}
}
String relative = "";
// is the target a child directory of the base directory?
// i.e., target = /a/b/c/d, base = /a/b/
if (commonIndex == base.length) {
relative = "." + pathSeparator + targetPath.substring(common.length());
}
else {
// determine how many directories we have to backtrack
for (int i = 1; i <= commonIndex; i++) {
relative += ".." + pathSeparator;
}
relative += targetPath.substring(common.length());
}
return relative;
}
public static String getRelativePath(String targetPath, String basePath) {
return getRelativePath(targetPath, basePath, File.pathSeparator);
}
}
public class RelativePathFinderTest extends TestCase {
public void testGetRelativePath() {
assertEquals("./stuff/xyz.dat", RelativePathFinder.getRelativePath(
"/var/data/stuff/xyz.dat", "/var/data/", "/"));
assertEquals("../../b/c", RelativePathFinder.getRelativePath("/a/b/c",
"/a/x/y/", "/"));
}
}
Cool!! J'ai besoin d'un peu de code comme celui-ci, mais pour comparer les chemins de répertoires sur des machines Linux. J'ai trouvé que cela ne fonctionnait pas dans les situations où un répertoire parent était la cible.
Voici une version de la méthode adaptée aux répertoires:
public static String getRelativePath(String targetPath, String basePath,
String pathSeparator) {
boolean isDir = false;
{
File f = new File(targetPath);
isDir = f.isDirectory();
}
// We need the -1 argument to split to make sure we get a trailing
// "" token if the base ends in the path separator and is therefore
// a directory. We require directory paths to end in the path
// separator -- otherwise they are indistinguishable from files.
String[] base = basePath.split(Pattern.quote(pathSeparator), -1);
String[] target = targetPath.split(Pattern.quote(pathSeparator), 0);
// First get all the common elements. Store them as a string,
// and also count how many of them there are.
String common = "";
int commonIndex = 0;
for (int i = 0; i < target.length && i < base.length; i++) {
if (target[i].equals(base[i])) {
common += target[i] + pathSeparator;
commonIndex++;
}
else break;
}
if (commonIndex == 0)
{
// Whoops -- not even a single common path element. This most
// likely indicates differing drive letters, like C: and D:.
// These paths cannot be relativized. Return the target path.
return targetPath;
// This should never happen when all absolute paths
// begin with / as in *nix.
}
String relative = "";
if (base.length == commonIndex) {
// Comment this out if you prefer that a relative path not start with ./
relative = "." + pathSeparator;
}
else {
int numDirsUp = base.length - commonIndex - (isDir?0:1); /* only subtract 1 if it is a file. */
// The number of directories we have to backtrack is the length of
// the base path MINUS the number of common path elements, minus
// one because the last element in the path isn't a directory.
for (int i = 1; i <= (numDirsUp); i++) {
relative += ".." + pathSeparator;
}
}
//if we are comparing directories then we
if (targetPath.length() > common.length()) {
//it's OK, it isn't a directory
relative += targetPath.substring(common.length());
}
return relative;
}
Je suppose que vous avez fromPath (un chemin absolu pour un dossier) et toPath (un chemin absolu pour un dossier/fichier) et que vous recherchez un chemin qui représente le fichier./folder dans toPath en tant que chemin relatif depuis fromPath (votre répertoire de travail actuel est fromPath ), un résultat similaire devrait alors fonctionner:
public static String getRelativePath(String fromPath, String toPath) {
// This weirdness is because a separator of '/' messes with String.split()
String regexCharacter = File.separator;
if (File.separatorChar == '\\') {
regexCharacter = "\\\\";
}
String[] fromSplit = fromPath.split(regexCharacter);
String[] toSplit = toPath.split(regexCharacter);
// Find the common path
int common = 0;
while (fromSplit[common].equals(toSplit[common])) {
common++;
}
StringBuffer result = new StringBuffer(".");
// Work your way up the FROM path to common ground
for (int i = common; i < fromSplit.length; i++) {
result.append(File.separatorChar).append("..");
}
// Work your way down the TO path
for (int i = common; i < toSplit.length; i++) {
result.append(File.separatorChar).append(toSplit[i]);
}
return result.toString();
}
Beaucoup de réponses déjà ici, mais j'ai constaté qu'ils ne traitaient pas tous les cas, tels que la base et la cible étant identiques. Cette fonction prend un répertoire répertoire et un chemin cible et renvoie le chemin relatif. Si aucun chemin relatif n'existe, le chemin cible est renvoyé. File.separator est inutile.
public static String getRelativePath (String baseDir, String targetPath) {
String[] base = baseDir.replace('\\', '/').split("\\/");
targetPath = targetPath.replace('\\', '/');
String[] target = targetPath.split("\\/");
// Count common elements and their length.
int commonCount = 0, commonLength = 0, maxCount = Math.min(target.length, base.length);
while (commonCount < maxCount) {
String targetElement = target[commonCount];
if (!targetElement.equals(base[commonCount])) break;
commonCount++;
commonLength += targetElement.length() + 1; // Directory name length plus slash.
}
if (commonCount == 0) return targetPath; // No common path element.
int targetLength = targetPath.length();
int dirsUp = base.length - commonCount;
StringBuffer relative = new StringBuffer(dirsUp * 3 + targetLength - commonLength + 1);
for (int i = 0; i < dirsUp; i++)
relative.append("../");
if (commonLength < targetLength) relative.append(targetPath.substring(commonLength));
return relative.toString();
}
Réussite les tests de Dónal, le seul changement - si aucune racine commune n’est renvoyée, le chemin cible (il peut déjà être relatif)
import static Java.util.Arrays.asList;
import static Java.util.Collections.nCopies;
import static org.Apache.commons.io.FilenameUtils.normalizeNoEndSeparator;
import static org.Apache.commons.io.FilenameUtils.separatorsToUnix;
import static org.Apache.commons.lang3.StringUtils.getCommonPrefix;
import static org.Apache.commons.lang3.StringUtils.isBlank;
import static org.Apache.commons.lang3.StringUtils.isNotEmpty;
import static org.Apache.commons.lang3.StringUtils.join;
import Java.io.File;
import Java.util.ArrayList;
import Java.util.List;
public class ResourceUtils {
public static String getRelativePath(String targetPath, String basePath, String pathSeparator) {
File baseFile = new File(basePath);
if (baseFile.isFile() || !baseFile.exists() && !basePath.endsWith("/") && !basePath.endsWith("\\"))
basePath = baseFile.getParent();
String target = separatorsToUnix(normalizeNoEndSeparator(targetPath));
String base = separatorsToUnix(normalizeNoEndSeparator(basePath));
String commonPrefix = getCommonPrefix(target, base);
if (isBlank(commonPrefix))
return targetPath.replaceAll("/", pathSeparator);
target = target.replaceFirst(commonPrefix, "");
base = base.replaceFirst(commonPrefix, "");
List<String> result = new ArrayList<>();
if (isNotEmpty(base))
result.addAll(nCopies(base.split("/").length, ".."));
result.addAll(asList(target.replaceFirst("^/", "").split("/")));
return join(result, pathSeparator);
}
}
Si vous écrivez un plugin Maven, vous pouvez utiliser Plexus 'PathTool :
import org.codehaus.plexus.util.PathTool;
String relativeFilePath = PathTool.getRelativeFilePath(file1, file2);
Voici une méthode qui résout un chemin relatif à partir d'un chemin de base, qu'ils se trouvent dans la même racine ou dans une racine différente:
public static String GetRelativePath(String path, String base){
final String SEP = "/";
// if base is not a directory -> return empty
if (!base.endsWith(SEP)){
return "";
}
// check if path is a file -> remove last "/" at the end of the method
boolean isfile = !path.endsWith(SEP);
// get URIs and split them by using the separator
String a = "";
String b = "";
try {
a = new File(base).getCanonicalFile().toURI().getPath();
b = new File(path).getCanonicalFile().toURI().getPath();
} catch (IOException e) {
e.printStackTrace();
}
String[] basePaths = a.split(SEP);
String[] otherPaths = b.split(SEP);
// check common part
int n = 0;
for(; n < basePaths.length && n < otherPaths.length; n ++)
{
if( basePaths[n].equals(otherPaths[n]) == false )
break;
}
// compose the new path
StringBuffer tmp = new StringBuffer("");
for(int m = n; m < basePaths.length; m ++)
tmp.append(".."+SEP);
for(int m = n; m < otherPaths.length; m ++)
{
tmp.append(otherPaths[m]);
tmp.append(SEP);
}
// get path string
String result = tmp.toString();
// remove last "/" if path is a file
if (isfile && result.endsWith(SEP)){
result = result.substring(0,result.length()-1);
}
return result;
}
Si Paths n'est pas disponible pour JRE 1.5 runtime ou maven plugin
package org.afc.util;
import Java.io.File;
import Java.util.LinkedList;
import Java.util.List;
public class FileUtil {
public static String getRelativePath(String basePath, String filePath) {
return getRelativePath(new File(basePath), new File(filePath));
}
public static String getRelativePath(File base, File file) {
List<String> bases = new LinkedList<String>();
bases.add(0, base.getName());
for (File parent = base.getParentFile(); parent != null; parent = parent.getParentFile()) {
bases.add(0, parent.getName());
}
List<String> files = new LinkedList<String>();
files.add(0, file.getName());
for (File parent = file.getParentFile(); parent != null; parent = parent.getParentFile()) {
files.add(0, parent.getName());
}
int overlapIndex = 0;
while (overlapIndex < bases.size() && overlapIndex < files.size() && bases.get(overlapIndex).equals(files.get(overlapIndex))) {
overlapIndex++;
}
StringBuilder relativePath = new StringBuilder();
for (int i = overlapIndex; i < bases.size(); i++) {
relativePath.append("..").append(File.separatorChar);
}
for (int i = overlapIndex; i < files.size(); i++) {
relativePath.append(files.get(i)).append(File.separatorChar);
}
relativePath.deleteCharAt(relativePath.length() - 1);
return relativePath.toString();
}
}