stringutils.java

这个是网络上下载的一个struct框架的程序

/**
 * $RCSfile: StringUtils.java,v $
 * $Revision: 1.23 $
 * $Date: 2003/04/15 21:04:29 $
 *
 * 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.struts2.framework.util;
import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.text.BreakIterator;
import java.util.ArrayList;
import java.util.Date;
import java.util.Locale;
import java.util.Random;

import org.apache.oro.text.perl.Perl5Util;
/**
 * 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 string.
     *
     * @param string 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 string, String oldString, String newString) {
        if (string == null) {
            return null;
        }
        // If the newString is null or zero length, just return the string since there's nothing
        // to replace.
        if (newString == null) {
            return string;
        }
        int i=0;
        // Make sure that oldString appears at least once before doing any processing.
        if ( ( i=string.indexOf(oldString, i) ) >= 0 ) {
            // Use char []'s, as they are more efficient to deal with.
            char [] string2 = string.toCharArray();
            char [] newString2 = newString.toCharArray();
            int oLength = oldString.length();
            StringBuffer buf = new StringBuffer(string2.length);
            buf.append(string2, 0, i).append(newString2);
            i += oLength;
            int j = i;
            // Replace all remaining instances of oldString with newString.
            while ( ( i=string.indexOf(oldString, i) ) > 0 ) {
                buf.append(string2, j, i-j).append(newString2);
                i += oLength;
                j = i;
            }
            buf.append(string2, j, string2.length - j);
            return buf.toString();
        }
        return string;
    }

    /**
     * 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 and strips out all tags except <br> tags while still leaving
     * the tag body intact.
     *
     * @param in the text to be converted.
     * @return the input string with all tags removed.
     */
    public static final String stripTags(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 + 3 < len && input[i+1] == 'b' && input[i+2] == 'r' && input[i+3] == '>') {
                    i += 3;
                    continue;
                }
                if (i > last) {
                    if (last > 0) {
                        out.append(" ");
                    }
                    out.append(input, last, i - last);
                }
                last = i + 1;
            }
            else if (ch == '>') {
                last = i + 1;
            }
        }
        if (last == 0) {
            return in;
        }
        if (i > last) {
            out.append(input, last, i - last);
        }
        return out.toString();
    }

    /**
     * This method takes a string which may contain HTML tags (ie, &lt;b&gt;,
     * &lt;table&gt;, etc) and converts the '&lt'' and '&gt;' characters to
     * their HTML escape sequences.
     *
     * @param in the text to be converted.
     * @return the input string with the characters '&lt;' and '&gt;' 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);
            } else if (ch == '"') {
                if (i > last) {
                    out.append(input, last, i - last);
                }
                last = i + 1;
                out.append(QUOTE_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