Java实现的文本字符串操作工具类实例【数据替换，加密解密操作】

package com.gcloud.common;import org.apache.commons.lang.StringUtils;import java.security.MessageDigest;import java.security.NoSuchAlgorithmException;import java.text.BreakIterator;import java.util.ArrayList;import java.util.Date;import java.util.Random;/** * 文本字符串工具类 * Created by charlin on 2017/9/10. */public class TextUtil {  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();  private final static String[] hex = { "00", "01", "02", "03", "04", "05",      "06", "07", "08", "09", "0A", "0B", "0C", "0D", "0E", "0F", "10",      "11", "12", "13", "14", "15", "16", "17", "18", "19", "1A", "1B",      "1C", "1D", "1E", "1F", "20", "21", "22", "23", "24", "25", "26",      "27", "28", "29", "2A", "2B", "2C", "2D", "2E", "2F", "30", "31",      "32", "33", "34", "35", "36", "37", "38", "39", "3A", "3B", "3C",      "3D", "3E", "3F", "40", "41", "42", "43", "44", "45", "46", "47",      "48", "49", "4A", "4B", "4C", "4D", "4E", "4F", "50", "51", "52",      "53", "54", "55", "56", "57", "58", "59", "5A", "5B", "5C", "5D",      "5E", "5F", "60", "61", "62", "63", "64", "65", "66", "67", "68",      "69", "6A", "6B", "6C", "6D", "6E", "6F", "70", "71", "72", "73",      "74", "75", "76", "77", "78", "79", "7A", "7B", "7C", "7D", "7E",      "7F", "80", "81", "82", "83", "84", "85", "86", "87", "88", "89",      "8A", "8B", "8C", "8D", "8E", "8F", "90", "91", "92", "93", "94",      "95", "96", "97", "98", "99", "9A", "9B", "9C", "9D", "9E", "9F",      "A0", "A1", "A2", "A3", "A4", "A5", "A6", "A7", "A8", "A9", "AA",      "AB", "AC", "AD", "AE", "AF", "B0", "B1", "B2", "B3", "B4", "B5",      "B6", "B7", "B8", "B9", "BA", "BB", "BC", "BD", "BE", "BF", "C0",      "C1", "C2", "C3", "C4", "C5", "C6", "C7", "C8", "C9", "CA", "CB",      "CC", "CD", "CE", "CF", "D0", "D1", "D2", "D3", "D4", "D5", "D6",      "D7", "D8", "D9", "DA", "DB", "DC", "DD", "DE", "DF", "E0", "E1",      "E2", "E3", "E4", "E5", "E6", "E7", "E8", "E9", "EA", "EB", "EC",      "ED", "EE", "EF", "F0", "F1", "F2", "F3", "F4", "F5", "F6", "F7",      "F8", "F9", "FA", "FB", "FC", "FD", "FE", "FF" };  private final static byte[] val = { 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,      0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,      0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,      0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,      0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x00, 0x01,      0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x3F, 0x3F, 0x3F,      0x3F, 0x3F, 0x3F, 0x3F, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x3F,      0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,      0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,      0x3F, 0x3F, 0x3F, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x3F, 0x3F,      0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,      0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,      0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,      0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,      0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,      0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,      0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,      0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,      0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,      0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,      0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,      0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,      0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,      0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F };  private static MessageDigest digest = null;  /**   * 替换字符串   * @param line   * @param oldStr   * @param newStr   * @return   */  public static String replace(String line , String oldStr, String newStr){    if (StringUtils.isEmpty(line)) return null;    int index = 0;    if ((index = line.indexOf(oldStr, index)) >= 0){      char[] charArray = line.toCharArray();      char[] newStrArray = newStr.toCharArray();      int oldLen = oldStr.length();      StringBuffer buf = new StringBuffer(charArray.length);      buf.append(charArray, 0, index).append(newStrArray);      index += oldLen;      int i = index;      while((index = line.indexOf(oldStr, index)) > 0){        buf.append(charArray, i, index - i).append(newStrArray);        index += oldLen;        i = index;      }      buf.append(charArray, i, charArray.length - i);      return buf.toString();    }    return line;  }  /**   * 替换字符串,并存入替换次数   * @param line   * @param oldStr   * @param newStr   * @return   */  public static String replace(String line , String oldStr, String newStr, int[] countArr){    if (StringUtils.isEmpty(line)) return null;    int index = 0;    if ((index = line.indexOf(oldStr, index)) >= 0){      int count = 0;      count++;      char[] charArray = line.toCharArray();      char[] newStrArray = newStr.toCharArray();      int oldLen = oldStr.length();      StringBuffer buf = new StringBuffer(charArray.length);      buf.append(charArray, 0, index).append(newStrArray);      index += oldLen;      int i = index;      while((index = line.indexOf(oldStr, index)) > 0){        buf.append(charArray, i, index - i).append(newStrArray);        index += oldLen;        i = index;        count++;      }      buf.append(charArray, i, charArray.length - i);      countArr[0] = count;      return buf.toString();    }    return line;  }  /**   * 替换字符串，不区分大小写   * @param line   * @param oldStr   * @param newStr   * @return   */  public static String replaceIgnoreCase(String line , String oldStr, String newStr){    if (StringUtils.isEmpty(line)) return null;    int index = 0;    line = line.toLowerCase();    oldStr = oldStr.toLowerCase();    if ((index = line.indexOf(oldStr, index)) >= 0){      char[] charArray = line.toCharArray();      char[] newStrArray = newStr.toCharArray();      int oldLen = oldStr.length();      StringBuffer buf = new StringBuffer(charArray.length);      buf.append(charArray, 0, index).append(newStrArray);      index += oldLen;      int i = index;      while((index = line.indexOf(oldStr, index)) > 0){        buf.append(charArray, i, index - i).append(newStrArray);        index += oldLen;        i = index;      }      buf.append(charArray, i, charArray.length - i);      return buf.toString();    }    return line;  }  /**   * 替换字符串，不区分大小写, 并存入替换次数   * @param line   * @param oldStr   * @param newStr   * @return   */  public static String replaceIgnoreCase(String line , String oldStr, String newStr, int[] countArr){    if (StringUtils.isEmpty(line)) return null;    int index = 0;    line = line.toLowerCase();    oldStr = oldStr.toLowerCase();    if ((index = line.indexOf(oldStr, index)) >= 0){      char[] charArray = line.toCharArray();      char[] newStrArray = newStr.toCharArray();      int oldLen = oldStr.length();      StringBuffer buf = new StringBuffer(charArray.length);      buf.append(charArray, 0, index).append(newStrArray);      index += oldLen;      int i = index;      int count = 0;      while((index = line.indexOf(oldStr, index)) > 0){        count ++;        buf.append(charArray, i, index - i).append(newStrArray);        index += oldLen;        i = index;      }      buf.append(charArray, i, charArray.length - i);      countArr[0] = count;      return buf.toString();    }    return line;  }  /**   * 替换页面html标签   * @param htmlStr   * @return   */  public static String escapeHTMLTags(String htmlStr) {    if (StringUtils.isEmpty(htmlStr)) return null;    char ch;    int last = 0;    char[] htmlStrArr = htmlStr.toCharArray();    int len = htmlStrArr.length;    StringBuffer outBuf = new StringBuffer((int) (len * 1.3));    int i = 0;    for (; i < len; i++) {      ch = htmlStrArr[i];      if (ch > '>') {        continue;      } else if (ch == '<') {        if (i > last) {          outBuf.append(htmlStrArr, last, i - last);        }        last = i + 1;        outBuf.append(LT_ENCODE);      } else if (ch == '>') {        if (i > last) {          outBuf.append(htmlStrArr, last, i - last);        }        last = i + 1;        outBuf.append(GT_ENCODE);      }    }    if (last == 0) {      return htmlStr;    }    if (i > last) {      outBuf.append(htmlStrArr, last, i - last);    }    return outBuf.toString();  }  /**   * 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.   * @param data   * @return   */  public synchronized static String hash(String data) {    if (digest == null) {      try {        digest = MessageDigest.getInstance("MD5");      } catch (NoSuchAlgorithmException e) {        System.err.println("Failed to load the MD5 MessageDigest.Jive will be unable to function normally.");        e.printStackTrace();      }    }    digest.update(data.getBytes());    return encodeHex(digest.digest());  }  /**   * Turns an array of bytes into a String representing each byte as an   * unsigned hex number.   * @param bytes   * @return   */  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   * @return   */  public static 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.  // *********************************************************************  /**   * 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.   * @param data a base64 encode byte array to decode.   * @return the decoded String.   */  public static String decodeBase64(byte[] data) {    int c, c1;    int len = data.length;    StringBuffer ret = new StringBuffer((len * 3) / 4);    for (int i = 0; i < len; ++i) {      c = cvt.indexOf(data[i]);      ++i;      c1 = cvt.indexOf(data[i]);      c = ((c << 2) | ((c1 >> 4) & 0x3));      ret.append((char) c);      if (++i < len) {        c = data[i];        if (fillchar == c)          break;        c = cvt.indexOf((char) c);        c1 = ((c1 << 4) & 0xf0) | ((c >> 2) & 0xf);        ret.append((char) c1);      }      if (++i < len) {        c1 = data[i];        if (fillchar == c1)          break;        c1 = cvt.indexOf((char) c1);        c = ((c << 6) & 0xc0) | c1;        ret.append((char) c);      }    }    return ret.toString();  }  private static final int fillchar = '=';  private static final String cvt = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" + "abcdefghijklmnopqrstuvwxyz" + "0123456789+/";  /**   * Converts a line of text into an array of lower case words using a   * BreakIterator.wordInstance().   * This method is under the Jive Open Source Software License and was   * written by Mark Imbriaco.   * @param text a String of text to convert into an array of words   * @return text broken up into an array of words.   */  public static final String[] toLowerCaseWordArray(String text) {    if (text == null || text.length() == 0) {      return new String[0];    }    ArrayList wordList = new ArrayList();    BreakIterator boundary = BreakIterator.getWordInstance();    boundary.setText(text);    int start = 0;    for (int end = boundary.next(); end != BreakIterator.DONE; start = end, end = boundary.next()) {      String tmp = text.substring(start, end).trim();      tmp = replace(tmp, "+", "");      tmp = replace(tmp, "/", "");      tmp = replace(tmp, "//", "");      tmp = replace(tmp, "#", "");      tmp = replace(tmp, "*", "");      tmp = replace(tmp, ")", "");      tmp = replace(tmp, "(", "");      tmp = replace(tmp, "&", "");      if (tmp.length() > 0) {        wordList.add(tmp);      }    }    return (String[]) wordList.toArray(new String[wordList.size()]);  }  /**   * Pseudo-random number generator object for use with randomString(). The   * Random class is not considered to be cryptographically secure, so only   * use these random Strings for low to medium security applications.   */  private static Random randGen = new Random();  /**   * Array of numbers and letters of mixed case. Numbers appear in the list   * twice so that there is a more equal chance that a number will be picked.   * We can use the array to get a random number or letter by picking a random   * array index.   */  private static char[] numbersAndLetters = ("0123456789abcdefghijklmnopqrstuvwxyz" + "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ").toCharArray();  /**   * Returns a random String of numbers and letters (lower and upper case) of   * the specified length. The method uses the Random class that is built-in   * to Java which is suitable for low to medium grade security uses. This   * means that the output is only pseudo random, i.e., each number is   * mathematically generated so is not truly random.   * @param length the desired length of the random String to return.   * @return a random String of numbers and letters of the specified length.   */  public static final String randomString(int length) {    if (length < 1) {      return null;    }    char[] randBuffer = new char[length];    for (int i = 0; i < randBuffer.length; i++) {      randBuffer[i] = numbersAndLetters[randGen.nextInt(71)];    }    return new String(randBuffer);  }  /**   * Intelligently chops a String at a word boundary (whitespace) that occurs   * at the specified index in the argument or before. However, if there is a   * newline character before <code>length</code>, the String will be   * chopped there. If no newline or whitespace is found in   * <code>string</code> up to the index <code>length</code>, the String   * will chopped at <code>length</code>.   * <p>   * For example, chopAtWord("This is a nice String", 10) will return "This is   * a" which is the first word boundary less than or equal to 10 characters   * into the original String.   * @param string the String to chop.   * @param length   * @return a substring of <code>string</code> whose length is less than or   *     equal to <code>length</code>, and that is chopped at   *     whitespace.   */  public static final String chopAtWord(String string, int length) {    if (string == null) {      return string;    }    char[] charArray = string.toCharArray();    int sLength = string.length();    if (length < sLength) {      sLength = length;    }    // First check if there is a newline character before length; if so,    // chop word there.    for (int i = 0; i < sLength - 1; i++) {      // Windows      if (charArray[i] == '/r' && charArray[i + 1] == '/n') {        return string.substring(0, i + 1);      }      // Unix      else if (charArray[i] == '/n') {        return string.substring(0, i);      }    }    // Also check boundary case of Unix newline    if (charArray[sLength - 1] == '/n') {      return string.substring(0, sLength - 1);    }    // Done checking for newline, now see if the total string is less than    // the specified chop point.    if (string.length() < length) {      return string;    }    // No newline, so chop at the first whitespace.    for (int i = length - 1; i > 0; i--) {      if (charArray[i] == ' ') {        return string.substring(0, i).trim();      }    }    // Did not find word boundary so return original String chopped at    // specified length.    return string.substring(0, length);  }  /**   * Escapes all necessary characters in the String so that it can be used in   * an XML doc.   * @param string the string to escape.   * @return the string with appropriate characters escaped.   */  public static final String escapeForXML(String string) {    if (string == null) {      return null;    }    char ch;    int i = 0;    int last = 0;    char[] input = string.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(AMP_ENCODE);      } else if (ch == '"') {        if (i > last) {          out.append(input, last, i - last);        }        last = i + 1;        out.append(QUOTE_ENCODE);      }    }    if (last == 0) {      return string;    }    if (i > last) {      out.append(input, last, i - last);    }    return out.toString();  }  /**   * Unescapes the String by converting XML escape sequences back into normal   * characters.   * @param string the string to unescape.   * @return the string with appropriate characters unescaped.   */  public static final String unescapeFromXML(String string) {    string = replace(string, "<", "<");    string = replace(string, ">", ">");    string = replace(string, """, "/"");    return replace(string, "&", "&");  }  public static String escape(String s) {    StringBuffer sbuf = new StringBuffer();    int len = s.length();    for (int i = 0; i < len; i++) {      int ch = s.charAt(i);      if (ch == ' ') { // space : map to '+'        sbuf.append('+');      } else if ('A' <= ch && ch <= 'Z') { // 'A'..'Z' : as it was        sbuf.append((char) ch);      } else if ('a' <= ch && ch <= 'z') { // 'a'..'z' : as it was        sbuf.append((char) ch);      } else if ('0' <= ch && ch <= '9') { // '0'..'9' : as it was        sbuf.append((char) ch);      } else if (ch == '-'          || ch == '_' // unreserved : as it was          || ch == '.' || ch == '!' || ch == '~' || ch == '*'          || ch == '/'' || ch == '(' || ch == ')') {        sbuf.append((char) ch);      } else if (ch <= 0x007F) { // other ASCII : map to %XX        sbuf.append('%');        sbuf.append(hex[ch]);      } else { // unicode : map to %uXXXX        sbuf.append('%');        sbuf.append('u');        sbuf.append(hex[(ch >>> 8)]);        sbuf.append(hex[(0x00FF & ch)]);      }    }    return sbuf.toString();  }  public static String unescape(String s) {    StringBuffer sbuf = new StringBuffer();    int i = 0;    int len = s.length();    while (i < len) {      int ch = s.charAt(i);      if (ch == '+') { // + : map to ' '        sbuf.append(' ');      } else if ('A' <= ch && ch <= 'Z') { // 'A'..'Z' : as it was        sbuf.append((char) ch);      } else if ('a' <= ch && ch <= 'z') { // 'a'..'z' : as it was        sbuf.append((char) ch);      } else if ('0' <= ch && ch <= '9') { // '0'..'9' : as it was        sbuf.append((char) ch);      } else if (ch == '-'          || ch == '_' // unreserved : as it was          || ch == '.' || ch == '!' || ch == '~' || ch == '*'          || ch == '/'' || ch == '(' || ch == ')') {        sbuf.append((char) ch);      } else if (ch == '%') {        int cint = 0;        if ('u' != s.charAt(i + 1)) { // %XX : map to ascii(XX)          cint = (cint << 4) | val[s.charAt(i + 1)];          cint = (cint << 4) | val[s.charAt(i + 2)];          i += 2;        } else { // %uXXXX : map to unicode(XXXX)          cint = (cint << 4) | val[s.charAt(i + 2)];          cint = (cint << 4) | val[s.charAt(i + 3)];          cint = (cint << 4) | val[s.charAt(i + 4)];          cint = (cint << 4) | val[s.charAt(i + 5)];          i += 5;        }        sbuf.append((char) cint);      }      i++;    }    return sbuf.toString();  }  private static final char[] zeroArray = "0000000000000000".toCharArray();  /**   * Pads the supplied String with 0's to the specified length and returns the   * result as a new String. For example, if the initial String is "9999" and   * the desired length is 8, the result would be "00009999". This type of   * padding is useful for creating numerical values that need to be stored   * and sorted as character data. Note: the current implementation of this   * method allows for a maximum <tt>length</tt> of 16.   *   * @param string   *      the original String to pad.   * @param length   *      the desired length of the new padded String.   * @return a new String padded with the required number of 0's.   */  public static final String zeroPadString(String string, int length) {    if (string == null || string.length() > length) {      return string;    }    StringBuffer buf = new StringBuffer(length);    buf.append(zeroArray, 0, length - string.length()).append(string);    return buf.toString();  }  /**   * Formats a Date as a fifteen character long String made up of the Date's   * padded millisecond value.   * @return a Date encoded as a String.   */  public static final String dateToMillis(Date date) {    return zeroPadString(Long.toString(date.getTime()), 15);  }  public static void main(String[] args) {    System.out.println(replace("aaaaabbbcccc", "aa", "gg"));    System.out.println(replaceIgnoreCase("AAAAbbbcccc", "aa", "gg"));    System.out.println(escapeHTMLTags("AAAAbb<bcccc>"));  }}