stringutils.java

Jive是基于JSP/JAVA技术构架的一个大型BBS论坛系统,这是Jive论坛2.6版本的源程序

/**
 * $RCSfile: StringUtils.java,v $
 * $Revision: 1.6 $
 * $Date: 2002/06/20 21:02:21 $
 *
 * Copyright (C) 1999-2001 CoolServlets, Inc. All rights reserved.
 *
 * This software is the proprietary information of CoolServlets, Inc.
 * Use is subject to license terms.
 */

package com.jivesoftware.util;

import com.jivesoftware.oro.text.perl.Perl5Util;
import com.jivesoftware.forum.JiveGlobals;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.text.BreakIterator;
import java.util.*;

/**
 * Utility class to peform common String manipulation algorithms.
 */
public class StringUtils {

    // Constants used by escapeHTMLTags
    private static final char[] QUOTE_ENCODE = """.toCharArray();
    private static final char[] AMP_ENCODE = "&".toCharArray();
    private static final char[] LT_ENCODE = "<".toCharArray();
    private static final char[] GT_ENCODE = ">".toCharArray();

    /**
     * Replaces all instances of oldString with newString in line.
     *
     * @param line the String to search to perform replacements on
     * @param oldString the String that should be replaced by newString
     * @param newString the String that will replace all instances of oldString
     *
     * @return a String will all instances of oldString replaced by newString
     */
    public static final String replace(String line, String oldString, String newString)
    {
        if (line == null) {
            return null;
        }
        int i=0;
        if ( ( i=line.indexOf( oldString, i ) ) >= 0 ) {
            char [] line2 = line.toCharArray();
            char [] newString2 = newString.toCharArray();
            int oLength = oldString.length();
            StringBuffer buf = new StringBuffer(line2.length);
            buf.append(line2, 0, i).append(newString2);
            i += oLength;
            int j = i;
            while( ( i=line.indexOf( oldString, i ) ) > 0 ) {
                buf.append(line2, j, i-j).append(newString2);
                i += oLength;
                j = i;
            }
            buf.append(line2, j, line2.length - j);
            return buf.toString();
        }
        return line;
    }

    /**
     * Replaces all instances of oldString with newString in line with the
     * added feature that matches of newString in oldString ignore case.
     *
     * @param line the String to search to perform replacements on
     * @param oldString the String that should be replaced by newString
     * @param newString the String that will replace all instances of oldString
     *
     * @return a String will all instances of oldString replaced by newString
     */
    public static final String replaceIgnoreCase(String line, String oldString,
            String newString)
    {
        if (line == null) {
            return null;
        }
        String lcLine = line.toLowerCase();
        String lcOldString = oldString.toLowerCase();
        int i=0;
        if ((i=lcLine.indexOf(lcOldString, i)) >= 0) {
            char [] line2 = line.toCharArray();
            char [] newString2 = newString.toCharArray();
            int oLength = oldString.length();
            StringBuffer buf = new StringBuffer(line2.length);
            buf.append(line2, 0, i).append(newString2);
            i += oLength;
            int j = i;
            while ((i=lcLine.indexOf(lcOldString, i)) > 0) {
                buf.append(line2, j, i-j).append(newString2);
                i += oLength;
                j = i;
            }
            buf.append(line2, j, line2.length - j);
            return buf.toString();
        }
        return line;
    }

    /**
     * Replaces all instances of oldString with newString in line with the
     * added feature that matches of newString in oldString ignore case.
     * The count paramater is set to the number of replaces performed.
     *
     * @param line the String to search to perform replacements on
     * @param oldString the String that should be replaced by newString
     * @param newString the String that will replace all instances of oldString
     * @param count a value that will be updated with the number of replaces
     *      performed.
     *
     * @return a String will all instances of oldString replaced by newString
     */
    public static final String replaceIgnoreCase(String line, String oldString,
            String newString, int [] count)
    {
        if (line == null) {
            return null;
        }
        String lcLine = line.toLowerCase();
        String lcOldString = oldString.toLowerCase();
        int i=0;
        if ((i=lcLine.indexOf(lcOldString, i)) >= 0) {
            int counter = 1;
            char [] line2 = line.toCharArray();
            char [] newString2 = newString.toCharArray();
            int oLength = oldString.length();
            StringBuffer buf = new StringBuffer(line2.length);
            buf.append(line2, 0, i).append(newString2);
            i += oLength;
            int j = i;
            while ((i=lcLine.indexOf(lcOldString, i)) > 0) {
                counter++;
                buf.append(line2, j, i-j).append(newString2);
                i += oLength;
                j = i;
            }
            buf.append(line2, j, line2.length - j);
            count[0] = counter;
            return buf.toString();
        }
        return line;
    }

   /**
    * Replaces all instances of oldString with newString in line.
    * The count Integer is updated with number of replaces.
    *
    * @param line the String to search to perform replacements on
    * @param oldString the String that should be replaced by newString
    * @param newString the String that will replace all instances of oldString
    *
    * @return a String will all instances of oldString replaced by newString
    */
    public static final String replace(String line, String oldString,
            String newString, int[] count)
    {
        if (line == null) {
            return null;
        }
        int i=0;
        if ((i=line.indexOf(oldString, i)) >= 0) {
            int counter = 1;
            char [] line2 = line.toCharArray();
            char [] newString2 = newString.toCharArray();
            int oLength = oldString.length();
            StringBuffer buf = new StringBuffer(line2.length);
            buf.append(line2, 0, i).append(newString2);
            i += oLength;
            int j = i;
            while ((i=line.indexOf(oldString, i)) > 0) {
                counter++;
                buf.append(line2, j, i-j).append(newString2);
                i += oLength;
                j = i;
            }
            buf.append(line2, j, line2.length-j);
            count[0] = counter;
            return buf.toString();
        }
        return line;
    }

    /**
     * This method takes a string which may contain HTML tags (ie, <b>,
     * <table>, etc) and converts the '&lt'' and '>' characters to
     * their HTML escape sequences.
     *
     * @param in the text to be converted.
     * @return the input string with the characters '<' and '>' replaced
     *  with their HTML escape sequences.
     */
    public static final String escapeHTMLTags(String in) {
        if (in == null) {
            return null;
        }
        char ch;
        int i=0;
        int last=0;
        char[] input = in.toCharArray();
        int len = input.length;
        StringBuffer out = new StringBuffer((int)(len*1.3));
        for (; i < len; i++) {
            ch = input[i];
            if (ch > '>') {
                continue;
            } else if (ch == '<') {
                if (i > last) {
                    out.append(input, last, i - last);
                }
                last = i + 1;
                out.append(LT_ENCODE);
            } else if (ch == '>') {
                if (i > last) {
                    out.append(input, last, i - last);
                }
                last = i + 1;
                out.append(GT_ENCODE);
            }
        }
        if (last == 0) {
            return in;
        }
        if (i > last) {
            out.append(input, last, i - last);
        }
        return out.toString();
    }

    /**
     * Used by the hash method.
     */
    private static MessageDigest digest = null;

    /**
     * Hashes a String using the Md5 algorithm and returns the result as a
     * String of hexadecimal numbers. This method is synchronized to avoid
     * excessive MessageDigest object creation. If calling this method becomes
     * a bottleneck in your code, you may wish to maintain a pool of
     * MessageDigest objects instead of using this method.
     * <p>
     * A hash is a one-way function -- that is, given an
     * input, an output is easily computed. However, given the output, the
     * input is almost impossible to compute. This is useful for passwords
     * since we can store the hash and a hacker will then have a very hard time
     * determining the original password.
     * <p>
     * In Jive, every time a user logs in, we simply
     * take their plain text password, compute the hash, and compare the
     * generated hash to the stored hash. Since it is almost impossible that
     * two passwords will generate the same hash, we know if the user gave us
     * the correct password or not. The only negative to this system is that
     * password recovery is basically impossible. Therefore, a reset password
     * method is used instead.
     *
     * @param data the String to compute the hash of.
     * @return a hashed version of the passed-in String
     */
    public synchronized static final String hash(String data) {
        if (digest == null) {
            try {
                digest = MessageDigest.getInstance("MD5");
            }
            catch (NoSuchAlgorithmException nsae) {
                System.err.println("Failed to load the MD5 MessageDigest. " +
                "Jive will be unable to function normally.");
                nsae.printStackTrace();
            }
        }
        // Now, compute hash.
        digest.update(data.getBytes());
        return encodeHex(digest.digest());
    }

    /**
     * Turns an array of bytes into a String representing each byte as an
     * unsigned hex number.
     * <p>
     * Method by Santeri Paavolainen, Helsinki Finland 1996<br>
     * (c) Santeri Paavolainen, Helsinki Finland 1996<br>
     * Distributed under LGPL.
     *
     * @param bytes an array of bytes to convert to a hex-string
     * @return generated hex string
     */
    public static final String encodeHex(byte[] bytes) {
        StringBuffer buf = new StringBuffer(bytes.length * 2);
        int i;

        for (i = 0; i < bytes.length; i++) {
            if (((int) bytes[i] & 0xff) < 0x10) {
                buf.append("0");
            }
            buf.append(Long.toString((int) bytes[i] & 0xff, 16));
        }
        return buf.toString();
    }

    /**
     * Turns a hex encoded string into a byte array. It is specifically meant
     * to "reverse" the toHex(byte[]) method.
     *
     * @param hex a hex encoded String to transform into a byte array.
     * @return a byte array representing the hex String[
     */
    public static final byte[] decodeHex(String hex) {
        char [] chars = hex.toCharArray();
        byte[] bytes = new byte[chars.length/2];
        int byteCount = 0;
        for (int i=0; i<chars.length; i+=2) {
            byte newByte = 0x00;
            newByte |= hexCharToByte(chars[i]);
            newByte <<= 4;
            newByte |= hexCharToByte(chars[i+1]);
            bytes[byteCount] = newByte;
            byteCount++;
        }
        return bytes;
    }

    /**
     * Returns the the byte value of a hexadecmical char (0-f). It's assumed
     * that the hexidecimal chars are lower case as appropriate.
     *
     * @param ch a hexedicmal character (0-f)
     * @return the byte value of the character (0x00-0x0F)
     */
    private static final byte hexCharToByte(char ch) {
        switch(ch) {
            case '0': return 0x00;
            case '1': return 0x01;
            case '2': return 0x02;
            case '3': return 0x03;
            case '4': return 0x04;
            case '5': return 0x05;
            case '6': return 0x06;
            case '7': return 0x07;
            case '8': return 0x08;
            case '9': return 0x09;
            case 'a': return 0x0A;
            case 'b': return 0x0B;
            case 'c': return 0x0C;
            case 'd': return 0x0D;
            case 'e': return 0x0E;
            case 'f': return 0x0F;
        }
        return 0x00;
    }

    //*********************************************************************
    //* Base64 - a simple base64 encoder and decoder.
    //*
    //*     Copyright (c) 1999, Bob Withers - [e-mail]
    //*
    //* This code may be freely used for any purpose, either personal
    //* or commercial, provided the authors copyright notice remains
    //* intact.
    //*********************************************************************

    /**
     * Encodes a String as a base64 String.
     *
     * @param data a String to encode.
     * @return a base64 encoded String.
     */
    public static String encodeBase64(String data) {
        return encodeBase64(data.getBytes());
    }

    /**
     * Encodes a byte array into a base64 String.
     *
     * @param data a byte array to encode.
     * @return a base64 encode String.
     */
    public static String encodeBase64(byte[] data) {
        int c;
        int len = data.length;
        StringBuffer ret = new StringBuffer(((len / 3) + 1) * 4);
        for (int i = 0; i < len; ++i) {
            c = (data[i] >> 2) & 0x3f;
            ret.append(cvt.charAt(c));
            c = (data[i] << 4) & 0x3f;
            if (++i < len)
                c |= (data[i] >> 4) & 0x0f;

            ret.append(cvt.charAt(c));
            if (i < len) {
                c = (data[i] << 2) & 0x3f;
                if (++i < len)
                    c |= (data[i] >> 6) & 0x03;

                ret.append(cvt.charAt(c));
            }
            else {
                ++i;
                ret.append((char) fillchar);
            }

            if (i < len) {
                c = data[i] & 0x3f;
                ret.append(cvt.charAt(c));
            }
            else {
                ret.append((char) fillchar);
            }
        }
        return ret.toString();
    }

    /**
     * Decodes a base64 String.
     *
     * @param data a base64 encoded String to decode.
     * @return the decoded String.
     */
    public static String decodeBase64(String data) {
        return decodeBase64(data.getBytes());
    }

    /**
     * Decodes a base64 aray of bytes.