计算到文件之间的相对路径

// Copyright (C) 2001-2012 Michael Bayne, et al.

//package com.nowjava;

import java.io.File;
/** from 
NowJava.com - 时代Java**/

import java.io.IOException;


public class Main {

    /**

     * Computes a relative path between to Files

     *

     * @param file the file we're referencing

     * @param relativeTo the path from which we want to refer to the file

     */

    public static String computeRelativePath(File file, File relativeTo)

            throws IOException {

        String[] realDirs = getCanonicalPathElements(file);

        String[] relativeToDirs = getCanonicalPathElements(relativeTo);


        // Eliminate the common root

        int common = 0;

        for (; common < realDirs.length && common < relativeToDirs.length; common++) {

            if (!realDirs[common].equals(relativeToDirs[common])) {

                break;

            }

        }


        String relativePath = "";
        /** 
        来 自 
        nowjava.com - 时  代  Java
        **/


        // For each remaining level in the file path, add a ..

        for (int ii = 0; ii < (realDirs.length - common); ii++) {

            relativePath += ".." + File.separator;

        }


        // For each level in the resource path, add the path

        for (; common < relativeToDirs.length; common++) {

            relativePath += relativeToDirs[common] + File.separator;

        }


        return relativePath;

    }


    /**

     * Gets the individual path elements building up the canonical path to the given file.

     */

    public static String[] getCanonicalPa