apputility.java

JDesktop Integration Components （JDIC）

/*
 * Copyright (C) 2004 Sun Microsystems, Inc. All rights reserved. Use is
 * subject to license terms.
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the Lesser GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 * 
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 * USA.
 */ 

package org.jdesktop.jdic.filetypes.internal;

import java.net.URL;

/**
 * Utility class containing shared methods.
 */
public class AppUtility {

    /**
     * Suppress default constructor for noninstantiability.
     */
    private AppUtility() {}
    
    /**
     * Returns the file extension from the file part of the URL.
     * The returned file extension include the leading '.' character.
     * <P>
     * For example: if the URL is http://www.sun.com/index.html, the 
     * returned file extension is ".html".
     *
     * @param url the specified URL
     * @return the file extension of the file part of the URL.
     */
    public static String getFileExtensionByURL(URL url) {
        String trimFile = url.getFile().trim();

        if (trimFile == null || trimFile == "" || trimFile == "/") {
            return null;
        }
         
        int strIndex = trimFile.lastIndexOf("/");
        String filePart = trimFile.substring(strIndex + 1, trimFile.length());

        strIndex = filePart.lastIndexOf(".");
        if (strIndex == -1 || strIndex == filePart.length() - 1) {
            return null;
        } else {
            String fileExt = filePart.substring(strIndex, filePart.length());

            return fileExt;
        }
    }

    /**
     * Removes the leading '.' character from the specified file extension.
     *
     * @param fileExt the specified file extension.
     * @return file extension without a leading '.' character.
     */
    public static String removeDotFromFileExtension(String fileExt) {
        String temFileExt = fileExt;
        if (fileExt.charAt(0) == '.') {
            temFileExt = fileExt.substring(1, fileExt.length());
        }
        
        return temFileExt;
    }

    /**
     * Adds one leading '.' character for the specified file extension.
     * If the leading '.' character already exists, it just returns. 
     *
     * @param fileExt the specified file extension.
     * @return file extension with a leading '.' character.
     */
    public static String addDotToFileExtension(String fileExt) {
        String temFileExt = fileExt;
        if (fileExt.charAt(0) != '.') {
            String dotStr = ".";
            temFileExt = dotStr.concat(fileExt);
        }
       
        return temFileExt;
    }
}