/*-
 * <<
 * UAVStack
 * ==
 * Copyright (C) 2016 - 2017 UAVStack
 * ==
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * >>
 */

package com.creditease.agent.helpers;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.List;
import java.util.Locale;
import java.util.Set;
import java.util.StringTokenizer;
import java.util.TreeSet;
import java.util.regex.Pattern;

public class StringHelper {

    private static final String FOLDER_SEPARATOR = "/";

    private static final char EXTENSION_SEPARATOR = '.';

    private StringHelper() {

    }

    // Empty checks
    // -----------------------------------------------------------------------
    /**
     * <p>
     * Checks if a String is empty ("") or null.
     * </p>
     *
     * <pre>
     * StringUtils.isEmpty(null)      = true
     * StringUtils.isEmpty("")        = true
     * StringUtils.isEmpty(" ")       = false
     * StringUtils.isEmpty("bob")     = false
     * StringUtils.isEmpty("  bob  ") = false
     * </pre>
     *
     * <p>
     * NOTE: This method changed in Lang version 2.0. It no longer trims the String. That functionality is available in
     * isBlank().
     * </p>
     *
     * @param str
     *            the String to check, may be null
     * @return <code>true</code> if the String is empty or null
     */
    public static boolean isEmpty(String str) {

        return str == null || str.length() == 0 || "null".equals(str);
    }

    /**
     * <p>
     * Removes a substring only if it is at the end of a source string, otherwise returns the source string.
     * </p>
     *
     * <p>
     * A {@code null} source string will return {@code null}. An empty ("") source string will return the empty string.
     * A {@code null} search string will return the source string.
     * </p>
     *
     * <pre>
     * StringUtils.removeEnd(null, *) = null
     * StringUtils.removeEnd("", *) = ""
     * StringUtils.removeEnd(*, null) = *
     * StringUtils.removeEnd("www.domain.com", ".com.") = "www.domain.com"
     * StringUtils.removeEnd("www.domain.com", ".com") = "www.domain"
     * StringUtils.removeEnd("www.domain.com", "domain") = "www.domain.com"
     * StringUtils.removeEnd("abc", "") = "abc"
     * </pre>
     *
     * @param str
     *            the source String to search, may be null
     * @param remove
     *            the String to search for and remove, may be null
     * @return the substring with the string removed if found, {@code null} if null String input
     */
    public static String removeEnd(String str, String remove) {

        if (isEmpty(str) || isEmpty(remove)) {
            return str;
        }
        if (str.endsWith(remove)) {
            return str.substring(0, str.length() - remove.length());
        }
        return str;
    }

    // ---------------------------------------------------------------------
    // General convenience methods for working with Strings
    // ---------------------------------------------------------------------

    /**
     * Check that the given CharSequence is neither <code>null</code> nor of length 0. Note: Will return
     * <code>true</code> for a CharSequence that purely consists of whitespace.
     * <p>
     * 
     * <pre>
     * StringUtils.hasLength(null) = false
     * StringUtils.hasLength("") = false
     * StringUtils.hasLength(" ") = true
     * StringUtils.hasLength("Hello") = true
     * </pre>
     * 
     * @param str
     *            the CharSequence to check (may be <code>null</code>)
     * @return <code>true</code> if the CharSequence is not null and has length
     * @see #hasText(String)
     */
    public static boolean hasLength(CharSequence str) {

        return (str != null && str.length() > 0);
    }

    /**
     * Check that the given String is neither <code>null</code> nor of length 0. Note: Will return <code>true</code> for
     * a String that purely consists of whitespace.
     * 
     * @param str
     *            the String to check (may be <code>null</code>)
     * @return <code>true</code> if the String is not null and has length
     * @see #hasLength(CharSequence)
     */
    public static boolean hasLength(String str) {

        return hasLength((CharSequence) str);
    }

    /**
     * Check whether the given CharSequence has actual text. More specifically, returns <code>true</code> if the string
     * not <code>null</code>, its length is greater than 0, and it contains at least one non-whitespace character.
     * <p>
     * 
     * <pre>
     * StringUtils.hasText(null) = false
     * StringUtils.hasText("") = false
     * StringUtils.hasText(" ") = false
     * StringUtils.hasText("12345") = true
     * StringUtils.hasText(" 12345 ") = true
     * </pre>
     * 
     * @param str
     *            the CharSequence to check (may be <code>null</code>)
     * @return <code>true</code> if the CharSequence is not <code>null</code>, its length is greater than 0, and it does
     *         not contain whitespace only
     * @see java.lang.Character#isWhitespace
     */
    public static boolean hasText(CharSequence str) {

        if (!hasLength(str)) {
            return false;
        }
        int strLen = str.length();
        for (int i = 0; i < strLen; i++) {
            if (!Character.isWhitespace(str.charAt(i))) {
                return true;
            }
        }
        return false;
    }

    /**
     * Check whether the given String has actual text. More specifically, returns <code>true</code> if the string not
     * <code>null</code>, its length is greater than 0, and it contains at least one non-whitespace character.
     * 
     * @param str
     *            the String to check (may be <code>null</code>)
     * @return <code>true</code> if the String is not <code>null</code>, its length is greater than 0, and it does not
     *         contain whitespace only
     * @see #hasText(CharSequence)
     */
    public static boolean hasText(String str) {

        return hasText((CharSequence) str);
    }

    /**
     * Check whether the given CharSequence contains any whitespace characters.
     * 
     * @param str
     *            the CharSequence to check (may be <code>null</code>)
     * @return <code>true</code> if the CharSequence is not empty and contains at least 1 whitespace character
     * @see java.lang.Character#isWhitespace
     */
    public static boolean containsWhitespace(CharSequence str) {

        if (!hasLength(str)) {
            return false;
        }
        int strLen = str.length();
        for (int i = 0; i < strLen; i++) {
            if (Character.isWhitespace(str.charAt(i))) {
                return true;
            }
        }
        return false;
    }

    /**
     * Check whether the given String contains any whitespace characters.
     * 
     * @param str
     *            the String to check (may be <code>null</code>)
     * @return <code>true</code> if the String is not empty and contains at least 1 whitespace character
     * @see #containsWhitespace(CharSequence)
     */
    public static boolean containsWhitespace(String str) {

        return containsWhitespace((CharSequence) str);
    }

    /**
     * Trim leading and trailing whitespace from the given String.
     * 
     * @param str
     *            the String to check
     * @return the trimmed String
     * @see java.lang.Character#isWhitespace
     */
    public static String trimWhitespace(String str) {

        if (!hasLength(str)) {
            return str;
        }
        StringBuilder sb = new StringBuilder(str);
        while (sb.length() > 0 && Character.isWhitespace(sb.charAt(0))) {
            sb.deleteCharAt(0);
        }
        while (sb.length() > 0 && Character.isWhitespace(sb.charAt(sb.length() - 1))) {
            sb.deleteCharAt(sb.length() - 1);
        }
        return sb.toString();
    }

    /**
     * Trim <i>all</i> whitespace from the given String: leading, trailing, and inbetween characters.
     * 
     * @param str
     *            the String to check
     * @return the trimmed String
     * @see java.lang.Character#isWhitespace
     */
    public static String trimAllWhitespace(String str) {

        if (!hasLength(str)) {
            return str;
        }
        StringBuilder sb = new StringBuilder(str);
        int index = 0;
        while (sb.length() > index) {
            if (Character.isWhitespace(sb.charAt(index))) {
                sb.deleteCharAt(index);
            }
            else {
                index++;
            }
        }
        return sb.toString();
    }

    /**
     * Trim leading whitespace from the given String.
     * 
     * @param str
     *            the String to check
     * @return the trimmed String
     * @see java.lang.Character#isWhitespace
     */
    public static String trimLeadingWhitespace(String str) {

        if (!hasLength(str)) {
            return str;
        }
        StringBuilder sb = new StringBuilder(str);
        while (sb.length() > 0 && Character.isWhitespace(sb.charAt(0))) {
            sb.deleteCharAt(0);
        }
        return sb.toString();
    }

    /**
     * Trim trailing whitespace from the given String.
     * 
     * @param str
     *            the String to check
     * @return the trimmed String
     * @see java.lang.Character#isWhitespace
     */
    public static String trimTrailingWhitespace(String str) {

        if (!hasLength(str)) {
            return str;
        }
        StringBuilder sb = new StringBuilder(str);
        while (sb.length() > 0 && Character.isWhitespace(sb.charAt(sb.length() - 1))) {
            sb.deleteCharAt(sb.length() - 1);
        }
        return sb.toString();
    }

    /**
     * Trim all occurences of the supplied leading character from the given String.
     * 
     * @param str
     *            the String to check
     * @param leadingCharacter
     *            the leading character to be trimmed
     * @return the trimmed String
     */
    public static String trimLeadingCharacter(String str, char leadingCharacter) {

        if (!hasLength(str)) {
            return str;
        }
        StringBuilder sb = new StringBuilder(str);
        while (sb.length() > 0 && sb.charAt(0) == leadingCharacter) {
            sb.deleteCharAt(0);
        }
        return sb.toString();
    }

    /**
     * Trim all occurences of the supplied trailing character from the given String.
     * 
     * @param str
     *            the String to check
     * @param trailingCharacter
     *            the trailing character to be trimmed
     * @return the trimmed String
     */
    public static String trimTrailingCharacter(String str, char trailingCharacter) {

        if (!hasLength(str)) {
            return str;
        }
        StringBuilder sb = new StringBuilder(str);
        while (sb.length() > 0 && sb.charAt(sb.length() - 1) == trailingCharacter) {
            sb.deleteCharAt(sb.length() - 1);
        }
        return sb.toString();
    }

    /**
     * Test if the given String starts with the specified prefix, ignoring upper/lower case.
     * 
     * @param str
     *            the String to check
     * @param prefix
     *            the prefix to look for
     * @see java.lang.String#startsWith
     */
    public static boolean startsWithIgnoreCase(String str, String prefix) {

        if (str == null || prefix == null) {
            return false;
        }
        if (str.startsWith(prefix)) {
            return true;
        }
        if (str.length() < prefix.length()) {
            return false;
        }
        String lcStr = str.substring(0, prefix.length()).toLowerCase();
        String lcPrefix = prefix.toLowerCase();
        return lcStr.equals(lcPrefix);
    }

    /**
     * Test if the given String ends with the specified suffix, ignoring upper/lower case.
     * 
     * @param str
     *            the String to check
     * @param suffix
     *            the suffix to look for
     * @see java.lang.String#endsWith
     */
    public static boolean endsWithIgnoreCase(String str, String suffix) {

        if (str == null || suffix == null) {
            return false;
        }
        if (str.endsWith(suffix)) {
            return true;
        }
        if (str.length() < suffix.length()) {
            return false;
        }

        String lcStr = str.substring(str.length() - suffix.length()).toLowerCase();
        String lcSuffix = suffix.toLowerCase();
        return lcStr.equals(lcSuffix);
    }

    /**
     * Test whether the given string matches the given substring at the given index.
     * 
     * @param str
     *            the original string (or StringBuilder)
     * @param index
     *            the index in the original string to start matching against
     * @param substring
     *            the substring to match at the given index
     */
    public static boolean substringMatch(CharSequence str, int index, CharSequence substring) {

        for (int j = 0; j < substring.length(); j++) {
            int i = index + j;
            if (i >= str.length() || str.charAt(i) != substring.charAt(j)) {
                return false;
            }
        }
        return true;
    }

    /**
     * Count the occurrences of the substring in string s.
     * 
     * @param str
     *            string to search in. Return 0 if this is null.
     * @param sub
     *            string to search for. Return 0 if this is null.
     */
    public static int countOccurrencesOf(String str, String sub) {

        if (str == null || sub == null || str.length() == 0 || sub.length() == 0) {
            return 0;
        }
        int count = 0;
        int pos = 0;
        int idx;
        while ((idx = str.indexOf(sub, pos)) != -1) {
            ++count;
            pos = idx + sub.length();
        }
        return count;
    }

    /**
     * Replace all occurences of a substring within a string with another string.
     * 
     * @param inString
     *            String to examine
     * @param oldPattern
     *            String to replace
     * @param newPattern
     *            String to insert
     * @return a String with the replacements
     */
    public static String replace(String inString, String oldPattern, String newPattern) {

        if (!hasLength(inString) || !hasLength(oldPattern) || newPattern == null) {
            return inString;
        }
        StringBuilder sb = new StringBuilder();
        int pos = 0; // our position in the old string
        int index = inString.indexOf(oldPattern);
        // the index of an occurrence we've found, or -1
        int patLen = oldPattern.length();
        while (index >= 0) {
            sb.append(inString.substring(pos, index));
            sb.append(newPattern);
            pos = index + patLen;
            index = inString.indexOf(oldPattern, pos);
        }
        sb.append(inString.substring(pos));
        // remember to append any characters to the right of a match
        return sb.toString();
    }

    /**
     * Delete all occurrences of the given substring.
     * 
     * @param inString
     *            the original String
     * @param pattern
     *            the pattern to delete all occurrences of
     * @return the resulting String
     */
    public static String delete(String inString, String pattern) {

        return replace(inString, pattern, "");
    }

    /**
     * Delete any character in a given String.
     * 
     * @param inString
     *            the original String
     * @param charsToDelete
     *            a set of characters to delete. E.g. "az\n" will delete 'a's, 'z's and new lines.
     * @return the resulting String
     */
    public static String deleteAny(String inString, String charsToDelete) {

        if (!hasLength(inString) || !hasLength(charsToDelete)) {
            return inString;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < inString.length(); i++) {
            char c = inString.charAt(i);
            if (charsToDelete.indexOf(c) == -1) {
                sb.append(c);
            }
        }
        return sb.toString();
    }

    // ---------------------------------------------------------------------
    // Convenience methods for working with formatted Strings
    // ---------------------------------------------------------------------

    /**
     * Quote the given String with single quotes.
     * 
     * @param str
     *            the input String (e.g. "myString")
     * @return the quoted String (e.g. "'myString'"), or <code>null<code> if the input was <code>null</code>
     */
    public static String quote(String str) {

        return (str != null ? "'" + str + "'" : null);
    }

    /**
     * Turn the given Object into a String with single quotes if it is a String; keeping the Object as-is else.
     * 
     * @param obj
     *            the input Object (e.g. "myString")
     * @return the quoted String (e.g. "'myString'"), or the input object as-is if not a String
     */
    public static Object quoteIfString(Object obj) {

        return (obj instanceof String ? quote((String) obj) : obj);
    }

    /**
     * Unqualify a string qualified by a '.' dot character. For example, "this.name.is.qualified", returns "qualified".
     * 
     * @param qualifiedName
     *            the qualified name
     */
    public static String unqualify(String qualifiedName) {

        return unqualify(qualifiedName, '.');
    }

    /**
     * Unqualify a string qualified by a separator character. For example, "this:name:is:qualified" returns "qualified"
     * if using a ':' separator.
     * 
     * @param qualifiedName
     *            the qualified name
     * @param separator
     *            the separator
     */
    public static String unqualify(String qualifiedName, char separator) {

        return qualifiedName.substring(qualifiedName.lastIndexOf(separator) + 1);
    }

    /**
     * Capitalize a <code>String</code>, changing the first letter to upper case as per
     * {@link Character#toUpperCase(char)}. No other letters are changed.
     * 
     * @param str
     *            the String to capitalize, may be <code>null</code>
     * @return the capitalized String, <code>null</code> if null
     */
    public static String capitalize(String str) {

        return changeFirstCharacterCase(str, true);
    }

    /**
     * Uncapitalize a <code>String</code>, changing the first letter to lower case as per
     * {@link Character#toLowerCase(char)}. No other letters are changed.
     * 
     * @param str
     *            the String to uncapitalize, may be <code>null</code>
     * @return the uncapitalized String, <code>null</code> if null
     */
    public static String uncapitalize(String str) {

        return changeFirstCharacterCase(str, false);
    }

    private static String changeFirstCharacterCase(String str, boolean capitalize) {

        if (str == null || str.length() == 0) {
            return str;
        }
        StringBuilder sb = new StringBuilder(str.length());
        if (capitalize) {
            sb.append(Character.toUpperCase(str.charAt(0)));
        }
        else {
            sb.append(Character.toLowerCase(str.charAt(0)));
        }
        sb.append(str.substring(1));
        return sb.toString();
    }

    /**
     * Extract the filename from the given path, e.g. "mypath/myfile.txt" -> "myfile.txt".
     * 
     * @param path
     *            the file path (may be <code>null</code>)
     * @return the extracted filename, or <code>null</code> if none
     */
    public static String getFilename(String path) {

        if (path == null) {
            return null;
        }
        int separatorIndex = path.lastIndexOf(FOLDER_SEPARATOR);
        return (separatorIndex != -1 ? path.substring(separatorIndex + 1) : path);
    }

    /**
     * Extract the filename extension from the given path, e.g. "mypath/myfile.txt" -> "txt".
     * 
     * @param path
     *            the file path (may be <code>null</code>)
     * @return the extracted filename extension, or <code>null</code> if none
     */
    public static String getFilenameExtension(String path) {

        if (path == null) {
            return null;
        }
        int sepIndex = path.lastIndexOf(EXTENSION_SEPARATOR);
        return (sepIndex != -1 ? path.substring(sepIndex + 1) : null);
    }

    /**
     * Strip the filename extension from the given path, e.g. "mypath/myfile.txt" -> "mypath/myfile".
     * 
     * @param path
     *            the file path (may be <code>null</code>)
     * @return the path with stripped filename extension, or <code>null</code> if none
     */
    public static String stripFilenameExtension(String path) {

        if (path == null) {
            return null;
        }
        int sepIndex = path.lastIndexOf(EXTENSION_SEPARATOR);
        return (sepIndex != -1 ? path.substring(0, sepIndex) : path);
    }

    /**
     * Apply the given relative path to the given path, assuming standard Java folder separation (i.e. "/" separators);
     * 
     * @param path
     *            the path to start from (usually a full file path)
     * @param relativePath
     *            the relative path to apply (relative to the full file path above)
     * @return the full file path that results from applying the relative path
     */
    public static String applyRelativePath(String path, String relativePath) {

        int separatorIndex = path.lastIndexOf(FOLDER_SEPARATOR);
        if (separatorIndex != -1) {
            String newPath = path.substring(0, separatorIndex);
            if (!relativePath.startsWith(FOLDER_SEPARATOR)) {
                newPath += FOLDER_SEPARATOR;
            }
            return newPath + relativePath;
        }
        else {
            return relativePath;
        }
    }

    /**
     * Parse the given <code>localeString</code> into a {@link Locale}.
     * <p>
     * This is the inverse operation of {@link Locale#toString Locale's toString}.
     * 
     * @param localeString
     *            the locale string, following <code>Locale's</code> <code>toString()</code> format ("en", "en_UK",
     *            etc); also accepts spaces as separators, as an alternative to underscores
     * @return a corresponding <code>Locale</code> instance
     */
    public static Locale parseLocaleString(String localeString) {

        String[] parts = tokenizeToStringArray(localeString, "_ ", false, false);
        String language = (parts.length > 0 ? parts[0] : "");
        String country = (parts.length > 1 ? parts[1] : "");
        String variant = "";
        if (parts.length >= 2) {
            // There is definitely a variant, and it is everything after the country
            // code sans the separator between the country code and the variant.
            int endIndexOfCountryCode = localeString.indexOf(country) + country.length();
            // Strip off any leading '_' and whitespace, what's left is the variant.
            variant = trimLeadingWhitespace(localeString.substring(endIndexOfCountryCode));
            if (variant.startsWith("_")) {
                variant = trimLeadingCharacter(variant, '_');
            }
        }
        return (language.length() > 0 ? new Locale(language, country, variant) : null);
    }

    /**
     * Determine the RFC 3066 compliant language tag, as used for the HTTP "Accept-Language" header.
     * 
     * @param locale
     *            the Locale to transform to a language tag
     * @return the RFC 3066 compliant language tag as String
     */
    public static String toLanguageTag(Locale locale) {

        return locale.getLanguage() + (hasText(locale.getCountry()) ? "-" + locale.getCountry() : "");
    }

    /**
     * Copy the given Collection into a String array. The Collection must contain String elements only.
     * 
     * @param collection
     *            the Collection to copy
     * @return the String array (<code>null</code> if the passed-in Collection was <code>null</code>)
     */
    public static String[] toStringArray(Collection<String> collection) {

        if (collection == null) {
            return null;
        }
        return collection.toArray(new String[collection.size()]);
    }

    /**
     * Copy the given Enumeration into a String array. The Enumeration must contain String elements only.
     * 
     * @param enumeration
     *            the Enumeration to copy
     * @return the String array (<code>null</code> if the passed-in Enumeration was <code>null</code>)
     */
    public static String[] toStringArray(Enumeration<String> enumeration) {

        if (enumeration == null) {
            return null;
        }
        List<String> list = Collections.list(enumeration);
        return list.toArray(new String[list.size()]);
    }

    /**
     * Split a String at the first occurrence of the delimiter. Does not include the delimiter in the result.
     * 
     * @param toSplit
     *            the string to split
     * @param delimiter
     *            to split the string up with
     * @return a two element array with index 0 being before the delimiter, and index 1 being after the delimiter
     *         (neither element includes the delimiter); or <code>null</code> if the delimiter wasn't found in the given
     *         input String
     */
    public static String[] split(String toSplit, String delimiter) {

        if (!hasLength(toSplit) || !hasLength(delimiter)) {
            return null;
        }
        int offset = toSplit.indexOf(delimiter);
        if (offset < 0) {
            return null;
        }
        String beforeDelimiter = toSplit.substring(0, offset);
        String afterDelimiter = toSplit.substring(offset + delimiter.length());
        return new String[] { beforeDelimiter, afterDelimiter };
    }

    /**
     * Tokenize the given String into a String array via a StringTokenizer. Trims tokens and omits empty tokens.
     * <p>
     * The given delimiters string is supposed to consist of any number of delimiter characters. Each of those
     * characters can be used to separate tokens. A delimiter is always a single character; for multi-character
     * delimiters, consider using <code>delimitedListToStringArray</code>
     * 
     * @param str
     *            the String to tokenize
     * @param delimiters
     *            the delimiter characters, assembled as String (each of those characters is individually considered as
     *            delimiter).
     * @return an array of the tokens
     * @see java.util.StringTokenizer
     * @see java.lang.String#trim()
     * @see #delimitedListToStringArray
     */
    public static String[] tokenizeToStringArray(String str, String delimiters) {

        return tokenizeToStringArray(str, delimiters, true, true);
    }

    /**
     * Tokenize the given String into a String array via a StringTokenizer.
     * <p>
     * The given delimiters string is supposed to consist of any number of delimiter characters. Each of those
     * characters can be used to separate tokens. A delimiter is always a single character; for multi-character
     * delimiters, consider using <code>delimitedListToStringArray</code>
     * 
     * @param str
     *            the String to tokenize
     * @param delimiters
     *            the delimiter characters, assembled as String (each of those characters is individually considered as
     *            delimiter)
     * @param trimTokens
     *            trim the tokens via String's <code>trim</code>
     * @param ignoreEmptyTokens
     *            omit empty tokens from the result array (only applies to tokens that are empty after trimming;
     *            StringTokenizer will not consider subsequent delimiters as token in the first place).
     * @return an array of the tokens (<code>null</code> if the input String was <code>null</code>)
     * @see java.util.StringTokenizer
     * @see java.lang.String#trim()
     * @see #delimitedListToStringArray
     */
    public static String[] tokenizeToStringArray(String str, String delimiters, boolean trimTokens,
            boolean ignoreEmptyTokens) {

        if (str == null) {
            return null;
        }
        StringTokenizer st = new StringTokenizer(str, delimiters);
        List<String> tokens = new ArrayList<String>();
        while (st.hasMoreTokens()) {
            String token = st.nextToken();
            if (trimTokens) {
                token = token.trim();
            }
            if (!ignoreEmptyTokens || token.length() > 0) {
                tokens.add(token);
            }
        }
        return toStringArray(tokens);
    }

    /**
     * Take a String which is a delimited list and convert it to a String array.
     * <p>
     * A single delimiter can consists of more than one character: It will still be considered as single delimiter
     * string, rather than as bunch of potential delimiter characters - in contrast to
     * <code>tokenizeToStringArray</code>.
     * 
     * @param str
     *            the input String
     * @param delimiter
     *            the delimiter between elements (this is a single delimiter, rather than a bunch individual delimiter
     *            characters)
     * @return an array of the tokens in the list
     * @see #tokenizeToStringArray
     */
    public static String[] delimitedListToStringArray(String str, String delimiter) {

        return delimitedListToStringArray(str, delimiter, null);
    }

    /**
     * Take a String which is a delimited list and convert it to a String array.
     * <p>
     * A single delimiter can consists of more than one character: It will still be considered as single delimiter
     * string, rather than as bunch of potential delimiter characters - in contrast to
     * <code>tokenizeToStringArray</code>.
     * 
     * @param str
     *            the input String
     * @param delimiter
     *            the delimiter between elements (this is a single delimiter, rather than a bunch individual delimiter
     *            characters)
     * @param charsToDelete
     *            a set of characters to delete. Useful for deleting unwanted line breaks: e.g. "\r\n\f" will delete all
     *            new lines and line feeds in a String.
     * @return an array of the tokens in the list
     * @see #tokenizeToStringArray
     */
    public static String[] delimitedListToStringArray(String str, String delimiter, String charsToDelete) {

        if (str == null) {
            return new String[0];
        }
        if (delimiter == null) {
            return new String[] { str };
        }
        List<String> result = new ArrayList<String>();
        if ("".equals(delimiter)) {
            for (int i = 0; i < str.length(); i++) {
                result.add(deleteAny(str.substring(i, i + 1), charsToDelete));
            }
        }
        else {
            int pos = 0;
            int delPos;
            while ((delPos = str.indexOf(delimiter, pos)) != -1) {
                result.add(deleteAny(str.substring(pos, delPos), charsToDelete));
                pos = delPos + delimiter.length();
            }
            if (str.length() > 0 && pos <= str.length()) {
                // Add rest of String, but not in case of empty input.
                result.add(deleteAny(str.substring(pos), charsToDelete));
            }
        }
        return toStringArray(result);
    }

    /**
     * Convert a CSV list into an array of Strings.
     * 
     * @param str
     *            the input String
     * @return an array of Strings, or the empty array in case of empty input
     */
    public static String[] commaDelimitedListToStringArray(String str) {

        return delimitedListToStringArray(str, ",");
    }

    /**
     * Convenience method to convert a CSV string list to a set. Note that this will suppress duplicates.
     * 
     * @param str
     *            the input String
     * @return a Set of String entries in the list
     */
    public static Set<String> commaDelimitedListToSet(String str) {

        Set<String> set = new TreeSet<String>();
        String[] tokens = commaDelimitedListToStringArray(str);
        for (String token : tokens) {
            set.add(token);
        }
        return set;
    }

    @Deprecated
    public static boolean isNumeric(String str) {

        if (str == null || str.isEmpty()) {
            return false;
        }
        Pattern pattern = Pattern.compile("[0-9]*");
        return pattern.matcher(str).matches();
    }
    
    public static boolean isNaturalNumber(String str) {
        
        if (str == null || str.isEmpty()) {
            return false;
        }
        for (int i = 0; i < str.length(); i++) {
            if (str.charAt(i) < '0' || str.charAt(i) > '9') {
                return false;
            }
        }
        return true;
    }

    /**
     * get sub string before the token str
     * 
     * @param str
     * @param token
     * @return
     */
    public static String getSubStrBeforeToken(String str, String token) {

        int paramHttpSt = str.indexOf(token);

        if (paramHttpSt > -1) {
            str = str.substring(0, paramHttpSt);
        }
        return str;
    }

    /**
     * decode the "." to Hex
     * 
     * @param str
     * @return
     */
    public static String dotdecod(String src) {

        StringBuilder sb = new StringBuilder(src.length());
        char[] chars = src.toCharArray();
        for (int i = 0; i < chars.length; i++) {
            if (chars[i] == '.') {
                sb.append("/u" + Integer.toHexString(chars[i]));
            }
            else {
                sb.append(chars[i]);
            }
        }
        return sb.toString();
    }

    /**
     * 获取指定长度的随机数字组成的字符串
     * 
     * @param size
     * @return
     */
    public static String getRandomNumber(int size) {

        String num = "";
        for (int i = 0; i < size; i++) {
            double a = Math.random() * 9;
            a = Math.ceil(a);
            int randomNum = new Double(a).intValue();
            num += randomNum;
        }
        return num;
    }
    
    /**
     * @param collection
     * @param separator
     * @return
     */
    public static String join(Collection<String> collection, String separator) {
        if (collection == null) {
            return null;
        }
        return join(collection.toArray(new String[collection.size()]), separator);
    }

    /**
     * Array can not be empty, the value in an array is empty and not appended to a string
     * 
     * @param array
     * @param separator
     * @return
     */
    public static String join(String[] array, String separator) {
        if (array == null) {
            return null;
        }

        if (separator == null) {
            separator = "";
        }

        StringBuilder builder = new StringBuilder();

        for (int i = 0; i < array.length; i++) {
            if (i > 0) {
                builder.append(separator);
            }
            if (array[i] != null) {
                builder.append(array[i]);
            }
        }
        return builder.toString();
    }
    
    public static String removeContinuousDupChars(String str, char ch) {
        
        if(isEmpty(str)) {
            return str;
        }
        char[] strChars = str.toCharArray();
        int end = strChars.length;
        for (int i = 0; i < end - 1 ; i++) {
            if(strChars[i] == ch) {
                while ((i + 1 < end) && (strChars[i + 1] == ch)) {
                    copyChars(strChars, i, i + 1, end - i - 1);
                    end--;
                }
            }
        }
        String newStr = new String(strChars, 0, end);
        return newStr;
    }
    
    private static void copyChars(char[] chs, int dest, int src, int len) {
        for(int pos = 0 ; pos < len; pos++) {
            chs[pos + dest] = chs[pos + src];
        }
    }
}