tools.java

Rapla是一个灵活的多用户资源管理系统。它提供的一些功能有：日历GUI

 /*--------------------------------------------------------------------------*
 | Copyright (C) 2006 Gereon Fassbender, Christopher Kohlhaas               |
 |                                                                          |
 | This program 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. A copy of the license has been included with   |
 | these distribution in the COPYING file, if not go to www.fsf.org         |
 |                                                                          |
 | As a special exception, you are granted the permissions to link this     |
 | program with every library, which license fulfills the Open Source       |
 | Definition as published by the Open Source Initiative (OSI).             |
 *--------------------------------------------------------------------------*/
package org.rapla.components.util;

import java.io.IOException;
import java.io.Reader;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;

/** miscellaneous util methods.*/
public abstract class Tools
{
    
    /**  same as new Object[0].*/
    public static Object[] EMPTY_ARRAY = new Object[0];
    public static Class[] EMPTY_CLASS_ARRAY = new Class[0];
    public static String[] EMPTY_STRING_ARRAY = new String[0];
    public static Iterator EMPTY_ITERATOR = new ArrayList().iterator();
    /** an unmodifiable list with no elements. */
    public static List EMPTY_LIST = new ArrayList() {
        private static final long serialVersionUID = 1L;
        public boolean add(Object object) {
            throw new UnsupportedOperationException();
        }
        public void add(int index,Object object) {
            throw new UnsupportedOperationException();
        }
        public boolean addAll(Collection col) {
            throw new UnsupportedOperationException();
        }
        public boolean addAll(int index,Collection col) {
            throw new UnsupportedOperationException();
        }
        public Iterator iterator() {
            return EMPTY_ITERATOR;
        }
    };
    /** an unmodifiable set with no elements. */
    public static Set EMPTY_SET = new HashSet() {
        private static final long serialVersionUID = 1L;
        public boolean add(Object object) {
            throw new UnsupportedOperationException();
        }
        public boolean addAll(Collection col) {
            throw new UnsupportedOperationException();
        }
        public Iterator iterator() {
            return EMPTY_ITERATOR;
        }
    };

    /** test if 2 char arrays match. */
    public static boolean match(char[] p1, char[] p2) {
        boolean bMatch = true;
        if (p1.length == p2.length) {
            for (int i = 0; i<p1.length; i++) {
                if (p1[i] != p2[i]) {
                    bMatch = false;
                    break;
                }
            }
        } else {
            bMatch = false;
        }
        return bMatch;
    }

    private static boolean validStart(char c)
    {
        return (c == '_' || c =='-' || Character.isLetter(c)) ?
            true : false;
    }

    private static boolean validLetter(char c) {
        return (validStart(c) || Character.isDigit(c));
    }

    /** Rudimentary tests if the string is a valid xml-tag.*/
    public static boolean isKey(String key) {
        char[] c = key.toCharArray();
        if (c.length == 0)
            return false;
        if (!validStart(c[0]))
            return false;
        for (int i=0;i<c.length;i++) {
            if (!validLetter(c[i]))
                return false;
        }
        return true;
    }

    /** same as substring(0,width-1) except that it will not
        not throw an <code>ArrayIndexOutOfBoundsException</code> if string.length()&lt;width.
     */
    public static String left(String string,int width) {
        return string.substring(0, Math.min(string.length(), width -1));
    }

    /** Convert a byte array into a printable format containing aString of hexadecimal digit characters (two per byte).
     * This method is taken form the apache jakarata
     * tomcat project.
     */
    public static String convert(byte bytes[]) {
        StringBuffer sb = new StringBuffer(bytes.length * 2);
        for (int i = 0; i < bytes.length; i++) {
            sb.append(convertDigit((int) (bytes[i] >> 4)));
            sb.append(convertDigit((int) (bytes[i] & 0x0f)));
        }
        return (sb.toString());
    }

    /** Convert the specified value (0-15) to the corresponding hexadecimal digit.
     * This method is taken form the apache jakarata tomcat project.
     */
    public static char convertDigit(int value) {
        value &= 0x0f;
        if (value >= 10)
            return ((char) (value - 10 + 'a'));
        else
            return ((char) (value + '0'));
    }

    public static boolean equalsOrBothNull(Object o1, Object o2) {
        if (o1 == null) {
            if (o2 != null) {
                return false;
            }
        } else if ( o2 == null) {
            return false;
        } else if (!o1.equals( o2 ) ) {
            return false;
        }
        return true;
    }

    /** 1.3 compatibility method */
    public static String[] split(String stringToSplit, char delimiter) {
        List keys = new ArrayList();
        int lastIndex = 0;
        while( true ) {
            int index = stringToSplit.indexOf( delimiter,lastIndex);
            if ( index < 0)
            {
                String token = stringToSplit.substring( lastIndex  );
                if ( token.length() > 0)
                {
                    keys.add( token );
                }
                break;
            }
            String token = stringToSplit.substring( lastIndex , index );
            keys.add( token );
            lastIndex = index + 1;
        }
        return (String[])keys.toArray( new String[] {});

    }

    /** 1.3 compatibility method */
    public static String replaceAll( String string, String stringToReplace, String newString ) {
        if ( stringToReplace.equals( newString))
            return string;
        int length = stringToReplace.length();
        int oldPos = 0;
        while ( true ) {
            int pos = string.indexOf( stringToReplace,oldPos);
            if ( pos < 0 )
                return string;

            string = string.substring(0, pos) + newString + string.substring( pos + length);
            oldPos = pos + 1;
            if ( oldPos >= string.length()  )
                return string;

        }
    }

    /** reads a table from a csv file. You can specify a minimum number of columns */
    public static String[][] csvRead(Reader reader, int expectedColumns) throws IOException {
        //System.out.println( "Using Encoding " + reader.getEncoding() );
        StringBuffer buf = new StringBuffer();
        while (true) {
            int c = reader.read();
            if ( c == -1 )
                break;
            buf.append( (char) c );
        }
        String[] lines = split( buf.toString(),'\n');
        String[][] lineEntries = new String[ lines.length ][];
        for ( int i=0;i<lines.length; i++ ) {
            lineEntries[i] = split( lines[i],';');
            if ( lineEntries[i].length < expectedColumns ) {
                throw new IOException("Can't parse line " + i + "\n" + lines[i] + "\n Expected " + expectedColumns + " Entries. Found " + lineEntries[i].length);
            }
        }
        return lineEntries;
    }


}