规范化路径

/*

 * Copyright (c) 2007 Adobe Systems Incorporated

 *

 *  Permission is hereby granted, free of charge, to any person obtaining a copy of

 *  this software and associated documentation files (the "Software"), to deal in

 *  the Software without restriction, including without limitation the rights to

 *  use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of

 *  the Software, and to permit persons to whom the Software is furnished to do so,

 *  subject to the following conditions:

 *

 *  The above copyright notice and this permission notice shall be included in all

 *  copies or substantial portions of the Software.

 *

 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS

 *  FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR

 *  COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER

 *  IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN

 *  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

 *

 */

//package com.nowjava;
/* 
*来 自
 N o w  J a v a  . c o m
*/


import java.util.Stack;

import java.util.StringTokenizer;


public class Main {

    public static String normalizePath(String path)

            throws IllegalArgumentException {

        // Test for any ../ or ./

        if (path.indexOf("./") < 0)

            return path;

        Stack<String> pathSegments = new Stack<String>();

        StringTokenizer tokenizer = new StringTokenizer(path, "/");

        while (tokenizer.hasMoreTokens()) {
        /** from 
        nowjava**/

            String pathSegment = tokenizer.nextToken();

            if (".".equals(pathSegment))

                continue;

            if ("..".equals(pathSegment)) {

                if (pathSegments.size() == 0) {

                    throw new IllegalArgumentException("Invalid path: "

                            + path);

                }

                pathSegments.pop();

            } else {

                pathSegments.push(pathSegmen