stringutils.java

一些简要的公爵类一些简要的公爵类一些简要的公爵类

		return toStringArray(result);
	}

	/**
	 * Turn given source String array into sorted array.
	 * @param array the source array
	 * @return the sorted array (never <code>null</code>)
	 */
	public static String[] sortStringArray(String[] array) {
		if (ObjectUtils.isEmpty(array)) {
			return new String[0];
		}
		Arrays.sort(array);
		return array;
	}

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

	/**
	 * Remove duplicate Strings from the given array.
	 * Also sorts the array, as it uses a TreeSet.
	 * @param array the String array
	 * @return an array without duplicates, in natural sort order
	 */
	public static String[] removeDuplicateStrings(String[] array) {
		if (ObjectUtils.isEmpty(array)) {
			return array;
		}
		Set set = new TreeSet();
		for (int i = 0; i < array.length; i++) {
			set.add(array[i]);
		}
		return toStringArray(set);
	}

	/**
	 * 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};
	}

	/**
	 * Take an array Strings and split each element based on the given delimiter.
	 * A <code>Properties</code> instance is then generated, with the left of the
	 * delimiter providing the key, and the right of the delimiter providing the value.
	 * <p>Will trim both the key and value before adding them to the
	 * <code>Properties</code> instance.
	 * @param array the array to process
	 * @param delimiter to split each element using (typically the equals symbol)
	 * @return a <code>Properties</code> instance representing the array contents,
	 * or <code>null</code> if the array to process was null or empty
	 */
	public static Properties splitArrayElementsIntoProperties(String[] array, String delimiter) {
		return splitArrayElementsIntoProperties(array, delimiter, null);
	}

	/**
	 * Take an array Strings and split each element based on the given delimiter.
	 * A <code>Properties</code> instance is then generated, with the left of the
	 * delimiter providing the key, and the right of the delimiter providing the value.
	 * <p>Will trim both the key and value before adding them to the
	 * <code>Properties</code> instance.
	 * @param array the array to process
	 * @param delimiter to split each element using (typically the equals symbol)
	 * @param charsToDelete one or more characters to remove from each element
	 * prior to attempting the split operation (typically the quotation mark
	 * symbol), or <code>null</code> if no removal should occur
	 * @return a <code>Properties</code> instance representing the array contents,
	 * or <code>null</code> if the array to process was <code>null</code> or empty
	 */
	public static Properties splitArrayElementsIntoProperties(
			String[] array, String delimiter, String charsToDelete) {

		if (ObjectUtils.isEmpty(array)) {
			return null;
		}
		Properties result = new Properties();
		for (int i = 0; i < array.length; i++) {
			String element = array[i];
			if (charsToDelete != null) {
				element = deleteAny(array[i], charsToDelete);
			}
			String[] splittedElement = split(element, delimiter);
			if (splittedElement == null) {
				continue;
			}
			result.setProperty(splittedElement[0].trim(), splittedElement[1].trim());
		}
		return result;
	}

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

	/**
	 * Convenience method to return a Collection as a delimited (e.g. CSV)
	 * String. E.g. useful for <code>toString()</code> implementations.
	 * @param coll the Collection to display
	 * @param delim the delimiter to use (probably a ",")
	 * @param prefix the String to start each element with
	 * @param suffix the String to end each element with
	 */
	public static String collectionToDelimitedString(Collection coll, String delim, String prefix, String suffix) {
		if (CollectionUtils.isEmpty(coll)) {
			return "";
		}
		StringBuffer sb = new StringBuffer();
		Iterator it = coll.iterator();
		while (it.hasNext()) {
			sb.append(prefix).append(it.next()).append(suffix);
			if (it.hasNext()) {
				sb.append(delim);
			}
		}
		return sb.toString();
	}

	/**
	 * Convenience method to return a Collection as a delimited (e.g. CSV)
	 * String. E.g. useful for <code>toString()</code> implementations.
	 * @param coll the Collection to display
	 * @param delim the delimiter to use (probably a ",")
	 */
	public static String collectionToDelimitedString(Collection coll, String delim) {
		return collectionToDelimitedString(coll, delim, "", "");
	}

	/**
	 * Convenience method to return a Collection as a CSV String.
	 * E.g. useful for <code>toString()</code> implementations.
	 * @param coll the Collection to display
	 */
	public static String collectionToCommaDelimitedString(Collection coll) {
		return collectionToDelimitedString(coll, ",");
	}

	/**
	 * Convenience method to return a String array as a delimited (e.g. CSV)
	 * String. E.g. useful for <code>toString()</code> implementations.
	 * @param arr the array to display
	 * @param delim the delimiter to use (probably a ",")
	 */
	public static String arrayToDelimitedString(Object[] arr, String delim) {
		if (ObjectUtils.isEmpty(arr)) {
			return "";
		}
		StringBuffer sb = new StringBuffer();
		for (int i = 0; i < arr.length; i++) {
			if (i > 0) {
				sb.append(delim);
			}
			sb.append(arr[i]);
		}
		return sb.toString();
	}

	/**
	 * Convenience method to return a String array as a CSV String.
	 * E.g. useful for <code>toString()</code> implementations.
	 * @param arr the array to display
	 */
	public static String arrayToCommaDelimitedString(Object[] arr) {
		return arrayToDelimitedString(arr, ",");
	}

}