Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;
/*
 * This file is part of OpenVPN-Settings.
 *
 * Copyright  2009-2012  Friedrich Schuffelhut
 *
 * OpenVPN-Settings is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * OpenVPN-Settings is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with OpenVPN-Settings.  If not, see <http://www.gnu.org/licenses/>.
 *
 * Report bugs or new features at: http://code.google.com/p/android-openvpn-settings/
 * Contact the author at:          android.openvpn@schaeuffelhut.de
 */

public class Main {
    /**
     * The Unix separator character.
     */
    private static final char UNIX_SEPARATOR = '/';
    /**
     * The Windows separator character.
     */
    private static final char WINDOWS_SEPARATOR = '\\';

    /**
     * Gets the prefix from a full filename, such as <code>C:/</code>
     * or <code>~/</code>.
     * <p>
     * This method will handle a file in either Unix or Windows format.
     * The prefix includes the first slash in the full filename where applicable.
     * <pre>
     * Windows:
     * a\b\c.txt           --> ""          --> relative
     * \a\b\c.txt          --> "\"         --> current drive absolute
     * C:a\b\c.txt         --> "C:"        --> drive relative
     * C:\a\b\c.txt        --> "C:\"       --> absolute
     * \\server\a\b\c.txt  --> "\\server\" --> UNC
     *
     * Unix:
     * a/b/c.txt           --> ""          --> relative
     * /a/b/c.txt          --> "/"         --> absolute
     * ~/a/b/c.txt         --> "~/"        --> current user
     * ~                   --> "~/"        --> current user (slash added)
     * ~user/a/b/c.txt     --> "~user/"    --> named user
     * ~user               --> "~user/"    --> named user (slash added)
     * </pre>
     * <p>
     * The output will be the same irrespective of the machine that the code is running on.
     * ie. both Unix and Windows prefixes are matched regardless.
     *
     * @param filename  the filename to query, null returns null
     * @return the prefix of the file, null if invalid
     */
    public static String getPrefix(String filename) {
        if (filename == null) {
            return null;
        }
        int len = getPrefixLength(filename);
        if (len < 0) {
            return null;
        }
        if (len > filename.length()) {
            return filename + UNIX_SEPARATOR; // we know this only happens for unix
        }
        return filename.substring(0, len);
    }

    /**
     * Returns the length of the filename prefix, such as <code>C:/</code> or <code>~/</code>.
     * <p>
     * This method will handle a file in either Unix or Windows format.
     * <p>
     * The prefix length includes the first slash in the full filename
     * if applicable. Thus, it is possible that the length returned is greater
     * than the length of the input string.
     * <pre>
     * Windows:
     * a\b\c.txt           --> ""          --> relative
     * \a\b\c.txt          --> "\"         --> current drive absolute
     * C:a\b\c.txt         --> "C:"        --> drive relative
     * C:\a\b\c.txt        --> "C:\"       --> absolute
     * \\server\a\b\c.txt  --> "\\server\" --> UNC
     *
     * Unix:
     * a/b/c.txt           --> ""          --> relative
     * /a/b/c.txt          --> "/"         --> absolute
     * ~/a/b/c.txt         --> "~/"        --> current user
     * ~                   --> "~/"        --> current user (slash added)
     * ~user/a/b/c.txt     --> "~user/"    --> named user
     * ~user               --> "~user/"    --> named user (slash added)
     * </pre>
     * <p>
     * The output will be the same irrespective of the machine that the code is running on.
     * ie. both Unix and Windows prefixes are matched regardless.
     *
     * @param filename  the filename to find the prefix in, null returns -1
     * @return the length of the prefix, -1 if invalid or null
     */
    public static int getPrefixLength(String filename) {
        if (filename == null) {
            return -1;
        }
        int len = filename.length();
        if (len == 0) {
            return 0;
        }
        char ch0 = filename.charAt(0);
        if (ch0 == ':') {
            return -1;
        }
        if (len == 1) {
            if (ch0 == '~') {
                return 2; // return a length greater than the input
            }
            return (isSeparator(ch0) ? 1 : 0);
        } else {
            if (ch0 == '~') {
                int posUnix = filename.indexOf(UNIX_SEPARATOR, 1);
                int posWin = filename.indexOf(WINDOWS_SEPARATOR, 1);
                if (posUnix == -1 && posWin == -1) {
                    return len + 1; // return a length greater than the input
                }
                posUnix = (posUnix == -1 ? posWin : posUnix);
                posWin = (posWin == -1 ? posUnix : posWin);
                return Math.min(posUnix, posWin) + 1;
            }
            char ch1 = filename.charAt(1);
            if (ch1 == ':') {
                ch0 = Character.toUpperCase(ch0);
                if (ch0 >= 'A' && ch0 <= 'Z') {
                    if (len == 2 || isSeparator(filename.charAt(2)) == false) {
                        return 2;
                    }
                    return 3;
                }
                return -1;

            } else if (isSeparator(ch0) && isSeparator(ch1)) {
                int posUnix = filename.indexOf(UNIX_SEPARATOR, 2);
                int posWin = filename.indexOf(WINDOWS_SEPARATOR, 2);
                if ((posUnix == -1 && posWin == -1) || posUnix == 2 || posWin == 2) {
                    return -1;
                }
                posUnix = (posUnix == -1 ? posWin : posUnix);
                posWin = (posWin == -1 ? posUnix : posWin);
                return Math.min(posUnix, posWin) + 1;
            } else {
                return (isSeparator(ch0) ? 1 : 0);
            }
        }
    }

    /**
     * Checks if the character is a separator.
     * 
     * @param ch  the character to check
     * @return true if it is a separator character
     */
    private static boolean isSeparator(char ch) {
        return (ch == UNIX_SEPARATOR) || (ch == WINDOWS_SEPARATOR);
    }
}