stringutils.java

一个简单的java邮件系统源码

/*
 * Copyright 2002-2006 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 com.easyjf.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.Properties;
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
 * @author Rob Harrop
 * @since 16 April 2001
 * @see org.apache.commons.lang.StringUtils
 */
public abstract class StringUtils {

	private static final String FOLDER_SEPARATOR = "/";

	private static final String WINDOWS_FOLDER_SEPARATOR = "\\";

	private static final String TOP_PATH = "..";

	private static final String CURRENT_PATH = ".";

	private static final char EXTENSION_SEPARATOR = '.';


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

	/**
	 * 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 <code>null</code>
	 * @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 <code>null</code>
	 * @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 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;
		}
		StringBuffer buf = new StringBuffer(str);
		while (buf.length() > 0 && Character.isWhitespace(buf.charAt(0))) {
			buf.deleteCharAt(0);
		}
		while (buf.length() > 0 && Character.isWhitespace(buf.charAt(buf.length() - 1))) {
			buf.deleteCharAt(buf.length() - 1);
		}
		return buf.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;
		}
		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 (!hasLength(str)) {
			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();
	}


	/**
	 * 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);
	}

	/**
	 * 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 charsToDelete 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 charsToDelete) {
		if (inString == null || charsToDelete == null) {
			return inString;
		}
		StringBuffer out = new StringBuffer();
		for (int i = 0; i < inString.length(); i++) {
			char c = inString.charAt(i);
			if (charsToDelete.indexOf(c) == -1) {
				out.append(c);
			}
		}
		return out.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;
		}
		StringBuffer buf = new StringBuffer(str.length());
		if (capitalize) {
			buf.append(Character.toUpperCase(str.charAt(0)));
		}
		else {
			buf.append(Character.toLowerCase(str.charAt(0)));
		}
		buf.append(str.substring(1));
		return buf.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)) {