stringutils.java

OpenCMS内容管理入门指南

/*
 * This library is part of the code for the book: OpenCms for Developers
 *
 * Copyright (c) 2007, 2008 Dan Liliedahl
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package com.deepthoughts.rss;

public class StringUtils {
	public final static String NULLSTR = "";
	
    /**
     * Utility to determine if a character is an alphanumeric.
     * 
     * @param curChar
     * @return true if character is alpha, else false
     */
    public static boolean isAlpha(char curChar) {
    	return  ((curChar>='a') && (curChar<='z')) ||
    	      ((curChar>='A') && (curChar<='Z')) ||
    	      (curChar==':') || (curChar=='_') || (curChar=='.');
    }

    /**
     * This is a utility method for trimming text to the given size.  If the size
     * limit occurs within a word then the size will be increased to prevent a
     * break within the word. 
     * 
     * @param Text Text to trim
     * @param Size Desired size
     * @return Text trimmed to nearest word break
     */
    public static String trimUp(String Text, int Size) {
    	// skip to next non-alpha to prevent breaking in the middle of a word
    	while (Size < Text.length() && isAlpha(Text.charAt(Size))) {
    		Size++;
    	}
    	return Text.substring(0, Size);
    }

    /**
     * This is a utility method for trimming text to the given size.  If the size
     * limit occurs within a word then the size will be decreased to prevent a
     * break within the word. 
     * 
     * @param Text Text to trim
     * @param Size Desired size
     * @return Text trimmed to nearest word break
     */
    public static String trimDown(String Text, int Size) {
    	// skip to next non-alpha to prevent breaking in the middle of a word
    	while (Size > 0 && isAlpha(Text.charAt(Size))) {
    		Size--;
    	}
    	return Text.substring(0, Size);
    }
    
    public static boolean isNull(String str) {
    	return (null == str) || str.equals(NULLSTR);
    }
}