Home | History | Annotate | Download | only in util 
      1 /*
      2  * [The "BSD licence"]
      3  * Copyright (c) 2010 Ben Gruver
      4  * All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  * 3. The name of the author may not be used to endorse or promote products
     15  *    derived from this software without specific prior written permission.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25  * INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 package org.jf.util;
     30 
     31 import java.io.File;
     32 import java.io.IOException;
     33 import java.util.ArrayList;
     34 
     35 public class PathUtil {
     36     private PathUtil() {
     37     }
     38 
     39     public static File getRelativeFile(File baseFile, File fileToRelativize) throws IOException {
     40         if (baseFile.isFile()) {
     41             baseFile = baseFile.getParentFile();
     42         }
     43 
     44         return new File(getRelativeFileInternal(baseFile.getCanonicalFile(), fileToRelativize.getCanonicalFile()));
     45     }
     46 
     47     public static String getRelativePath(String basePath, String pathToRelativize) throws IOException {
     48         File baseFile = new File(basePath);
     49         if (baseFile.isFile()) {
     50             baseFile = baseFile.getParentFile();
     51         }
     52 
     53         return getRelativeFileInternal(baseFile.getCanonicalFile(),
     54                 new File(pathToRelativize).getCanonicalFile());
     55     }
     56 
     57     static String getRelativeFileInternal(File canonicalBaseFile, File canonicalFileToRelativize) {
     58         ArrayList<String> basePath = getPathComponents(canonicalBaseFile);
     59         ArrayList<String> pathToRelativize = getPathComponents(canonicalFileToRelativize);
     60 
     61         //if the roots aren't the same (i.e. different drives on a windows machine), we can't construct a relative
     62         //path from one to the other, so just return the canonical file
     63         if (!basePath.get(0).equals(pathToRelativize.get(0))) {
     64             return canonicalFileToRelativize.getPath();
     65         }
     66 
     67         int commonDirs;
     68         StringBuilder sb = new StringBuilder();
     69 
     70         for (commonDirs=1; commonDirs<basePath.size() && commonDirs<pathToRelativize.size(); commonDirs++) {
     71             if (!basePath.get(commonDirs).equals(pathToRelativize.get(commonDirs))) {
     72                 break;
     73             }
     74         }
     75 
     76         boolean first = true;
     77         for (int i=commonDirs; i<basePath.size(); i++) {
     78             if (!first) {
     79                 sb.append(File.separatorChar);
     80             } else {
     81                 first = false;
     82             }
     83 
     84             sb.append("..");
     85         }
     86 
     87         first = true;
     88         for (int i=commonDirs; i<pathToRelativize.size(); i++) {
     89             if (first) {
     90                 if (sb.length() != 0) {
     91                     sb.append(File.separatorChar);
     92                 }
     93                 first = false;
     94             } else {
     95                 sb.append(File.separatorChar);
     96             }
     97 
     98             sb.append(pathToRelativize.get(i));
     99         }
    100 
    101         if (sb.length() == 0) {
    102             return ".";
    103         }
    104 
    105         return sb.toString();
    106     }
    107 
    108     private static ArrayList<String> getPathComponents(File file) {
    109         ArrayList<String> path = new ArrayList<String>();
    110 
    111         while (file != null) {
    112             File parentFile = file.getParentFile();
    113 
    114             if (parentFile == null) {
    115                 path.add(0, file.getPath());
    116             } else {
    117                 path.add(0, file.getName());
    118             }
    119 
    120             file = parentFile;
    121         }
    122 
    123         return path;
    124     }
    125 }
    126