stringutils.java

一个关于Spring框架的示例应用程序,简单使用,可以参考.

/*
 * Copyright 2002-2004 the original author or authors.
 *
 * 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 org.springframework.util;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Locale;
import java.util.Set;
import java.util.StringTokenizer;
import java.util.TreeSet;

/**
 * Miscellaneous string utility methods. Mainly for internal use
 * within the framework; consider Jakarta's Commons Lang for a more
 * comprehensive suite of string utilities.
 *
 * <p>This class delivers some simple functionality that should really
 * be provided by the core Java String and StringBuffer classes, such
 * as the ability to replace all occurrences of a given substring in a
 * target string. It also provides easy-to-use methods to convert between
 * delimited strings, such as CSV strings, and collections and arrays.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @author Keith Donald
 * @since 16 April 2001
 * @see org.apache.commons.lang.StringUtils
 */
public abstract class StringUtils {

	private static final String FOLDER_SEPARATOR = "/";  // folder separator

	private static final String WINDOWS_FOLDER_SEPARATOR = "\\";	// Windows folder separator

	private static final String TOP_PATH = "..";  // top folder

	private static final String CURRENT_PATH = ".";  // current folder


	/**
	 * Check if a String has length.
	 * <p><pre>
	 * StringUtils.hasLength(null) = false
	 * StringUtils.hasLength("") = false
	 * StringUtils.hasLength(" ") = true
	 * StringUtils.hasLength("Hello") = true
	 * </pre>
	 * @param str the String to check, may be null
	 * @return <code>true</code> if the String is not null and has length
	 */
	public static boolean hasLength(String str) {
		return (str != null && str.length() > 0);
	}

	/**
	 * Check if a String has text. More specifically, returns <code>true</code>
	 * if the string not <code>null<code>, it's <code>length is > 0</code>, and
	 * it has 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 String to check, may be null
	 * @return <code>true</code> if the String is not null, length > 0,
	 * and not whitespace only
	 * @see java.lang.Character#isWhitespace
	 */
	public static boolean hasText(String str) {
		int strLen;
		if (str == null || (strLen = str.length()) == 0) {
			return false;
		}
		for (int i = 0; i < strLen; i++) {
			if (!Character.isWhitespace(str.charAt(i))) {
				return true;
			}
		}
		return false;
	}

	/**
	 * 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 (str.length() == 0) {
			return str;
		}
		StringBuffer buf = new StringBuffer(str);
		while (buf.length() > 0 && Character.isWhitespace(buf.charAt(0))) {
			buf.deleteCharAt(0);
		}
		return buf.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 (str.length() == 0) {
			return str;
		}
		StringBuffer buf = new StringBuffer(str);
		while (buf.length() > 0 && Character.isWhitespace(buf.charAt(buf.length() - 1))) {
			buf.deleteCharAt(buf.length() - 1);
		}
		return buf.toString();
	}


	/**
	 * 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, pos = 0, idx = 0;
		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 (inString == null) {
			return null;
		}
		if (oldPattern == null || newPattern == null) {
			return inString;
		}

		StringBuffer sbuf = new StringBuffer();
		// output StringBuffer we'll build up
		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) {
			sbuf.append(inString.substring(pos, index));
			sbuf.append(newPattern);
			pos = index + patLen;
			index = inString.indexOf(oldPattern, pos);
		}
		sbuf.append(inString.substring(pos));

		// remember to append any characters to the right of a match
		return sbuf.toString();
	}

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

	/**
	 * Delete any character in a given string.
	 * @param chars a set of characters to delete.
	 * E.g. "az\n" will delete 'a's, 'z's and new lines.
	 */
	public static String deleteAny(String inString, String chars) {
		if (inString == null || chars == null) {
			return inString;
		}
		StringBuffer out = new StringBuffer();
		for (int i = 0; i < inString.length(); i++) {
			char c = inString.charAt(i);
			if (chars.indexOf(c) == -1) {
				out.append(c);
			}
		}
		return out.toString();
	}


	/**
	 * 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
	 * @see java.util.StringTokenizer
	 * @see java.lang.String#trim
	 * @see #delimitedListToStringArray
	 */
	public static String[] tokenizeToStringArray(
			String str, String delimiters, boolean trimTokens, boolean ignoreEmptyTokens) {

		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 (String[]) tokens.toArray(new String[tokens.size()]);
	}

	/**
	 * 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();
		int pos = 0;
		int delPos = 0;