Android Path Normalize normalizePath(String path)

Description

normalize Path

License

Open Source License

Declaration

public static String normalizePath(String path) 

Method Source Code

//package com.java2s;
/*//  w  w w  .j  a  v  a2s . c o  m
 * Copyright (c) 2002-2012 Alibaba Group Holding Limited.
 * All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.util.StringTokenizer;

public class Main {
    private static final char COLON_CHAR = ':';
    private static final String UNC_PREFIX = "//";
    private static final String SLASH = "/";
    private static final char SLASH_CHAR = '/';
    private static final char BACKSLASH_CHAR = '\\';
    /** ??????????"." */
    public static final String CURRENT_DIR = ".";
    /** ?????????".." */
    public static final String UP_LEVEL_DIR = "..";

    public static String normalizePath(String path) {
        return normalizePath(path, isWindows());
    }

    private static String normalizePath(String path, boolean isWindows) {
        if (path == null) {
            return null;
        }

        path = path.trim();

        // ?"\\"??????"/"?????????
        path = path.replace(BACKSLASH_CHAR, SLASH_CHAR);

        // ?????????????????windows?????????"C:"??"//hostname"
        String prefix = getSystemDependentPrefix(path, isWindows);

        if (prefix == null) {
            return null;
        }

        path = path.substring(prefix.length());

        // ????????prefix???"/"??????????????prefix.length > 0
        if (prefix.length() > 0 || path.startsWith(SLASH)) {
            prefix += SLASH_CHAR;
        }

        // ???path???"/"
        boolean endsWithSlash = path.endsWith(SLASH);

        // ??????"."?".."
        StringTokenizer tokenizer = new StringTokenizer(path, "/");
        StringBuffer buffer = new StringBuffer(prefix.length()
                + path.length());
        int level = 0;

        buffer.append(prefix);

        while (tokenizer.hasMoreTokens()) {
            String element = tokenizer.nextToken();

            // ??"."
            if (CURRENT_DIR.equals(element)) {
                continue;
            }

            // ??".."
            if (UP_LEVEL_DIR.equals(element)) {
                if (level == 0) {
                    // ??prefix?????????????????????????
                    // ??null??????????
                    if (prefix.length() > 0) {
                        return null;
                    }

                    buffer.append(UP_LEVEL_DIR).append(SLASH_CHAR);
                } else {
                    level--;

                    boolean found = false;

                    for (int i = buffer.length() - 2; i >= prefix.length(); i--) {
                        if (buffer.charAt(i) == SLASH_CHAR) {
                            buffer.setLength(i + 1);
                            found = true;
                            break;
                        }
                    }

                    if (!found) {
                        buffer.setLength(prefix.length());
                    }
                }

                continue;
            }

            // ???path
            buffer.append(element).append(SLASH_CHAR);
            level++;
        }

        // ????????????"./"
        if (buffer.length() == 0) {
            buffer.append(CURRENT_DIR).append(SLASH_CHAR);
        }

        // ????????"/"
        if (!endsWithSlash && buffer.length() > prefix.length()
                && buffer.charAt(buffer.length() - 1) == SLASH_CHAR) {
            buffer.setLength(buffer.length() - 1);
        }

        return buffer.toString();
    }

    private static boolean isWindows() {
        return System.getProperty("os.name").startsWith("Windows");
    }

    private static String getSystemDependentPrefix(String path,
            boolean isWindows) {
        if (isWindows) {
            // ??UNC??
            if (path.startsWith(UNC_PREFIX)) {
                // ????UNC???"//"
                if (path.length() == UNC_PREFIX.length()) {
                    return null;
                }

                // ???????//hostname/subpath???//hostname
                int index = path.indexOf(SLASH, UNC_PREFIX.length());

                if (index != -1) {
                    return path.substring(0, index);
                } else {
                    return path;
                }
            }

            // ??Windows??????"c:/..."
            if (path.length() > 1 && path.charAt(1) == COLON_CHAR) {
                return path.substring(0, 2).toUpperCase();
            }
        }

        return "";
    }
}

Related

1. getCanonicalPath(File pFile)
2. normalizeFile(String path)
3. normalizePath(String path, boolean isWindows)
4. normalizeUnixPath(String path)
5. normalizeWindowsPath(String path)