strings.java

Wicket一个开发Java Web应用程序框架。它使得开发web应用程序变得容易而轻松。 Wicket利用一个POJO data beans组件使得它可以与任何持久层技术相结合。

					// Read the xxxx
					int value = 0;
					for (int i = 0; i < 4; i++)
					{
						aChar = in[off++];
						switch (aChar)
						{
							case '0' :
							case '1' :
							case '2' :
							case '3' :
							case '4' :
							case '5' :
							case '6' :
							case '7' :
							case '8' :
							case '9' :
								value = (value << 4) + aChar - '0';
								break;
							case 'a' :
							case 'b' :
							case 'c' :
							case 'd' :
							case 'e' :
							case 'f' :
								value = (value << 4) + 10 + aChar - 'a';
								break;
							case 'A' :
							case 'B' :
							case 'C' :
							case 'D' :
							case 'E' :
							case 'F' :
								value = (value << 4) + 10 + aChar - 'A';
								break;
							default :
								throw new IllegalArgumentException("Malformed \\uxxxx encoding.");
						}
					}
					out[outLen++] = (char)value;
				}
				else
				{
					if (aChar == 't')
					{
						aChar = '\t';
					}
					else if (aChar == 'r')
					{
						aChar = '\r';
					}
					else if (aChar == 'n')
					{
						aChar = '\n';
					}
					else if (aChar == 'f')
					{
						aChar = '\f';
					}
					out[outLen++] = aChar;
				}
			}
			else
			{
				out[outLen++] = aChar;
			}
		}
		return new String(out, 0, outLen);
	}

	/**
	 * Checks whether the <code>string</code> is considered empty. Empty means that the string may
	 * contain whitespace, but no visible characters.
	 * 
	 * "\n\t " is considered empty, while " a" is not.
	 * 
	 * @param string
	 *            The string
	 * @return True if the string is null or ""
	 */
	public static boolean isEmpty(final CharSequence string)
	{
		return string == null || string.length() == 0 || string.toString().trim().length() == 0;
	}

	/**
	 * Checks whether two strings are equals taken care of 'null' values and treating 'null' same as
	 * trim(string).equals("")
	 * 
	 * @param string1
	 * @param string2
	 * @return true, if both strings are equal
	 */
	public static boolean isEqual(final String string1, final String string2)
	{
		if ((string1 == null) && (string2 == null))
		{
			return true;
		}

		if (isEmpty(string1) && isEmpty(string2))
		{
			return true;
		}
		if (string1 == null || string2 == null)
		{
			return false;
		}

		return string1.equals(string2);
	}

	/**
	 * Converts the text in <code>s</code> to a corresponding boolean. On, yes, y, true and 1 are
	 * converted to <code>true</code>. Off, no, n, false and 0 (zero) are converted to
	 * <code>false</code>. An empty string is converted to <code>false</code>. Conversion is
	 * case-insensitive, and does <em>not</em> take internationalization into account.
	 * 
	 * 'Ja', 'Oui', 'Igen', 'Nein', 'Nee', 'Non', 'Nem' are all illegal values.
	 * 
	 * @param s
	 *            the value to convert into a boolean
	 * @return Boolean the converted value of <code>s</code>
	 * @throws StringValueConversionException
	 *             when the value of <code>s</code> is not recognized.
	 */
	public static boolean isTrue(final String s) throws StringValueConversionException
	{
		if (s != null)
		{
			if (s.equalsIgnoreCase("true"))
			{
				return true;
			}

			if (s.equalsIgnoreCase("false"))
			{
				return false;
			}

			if (s.equalsIgnoreCase("on") || s.equalsIgnoreCase("yes") || s.equalsIgnoreCase("y") ||
					s.equalsIgnoreCase("1"))
			{
				return true;
			}

			if (s.equalsIgnoreCase("off") || s.equalsIgnoreCase("no") || s.equalsIgnoreCase("n") ||
					s.equalsIgnoreCase("0"))
			{
				return false;
			}

			if (isEmpty(s))
			{
				return false;
			}

			throw new StringValueConversionException("Boolean value \"" + s + "\" not recognized");
		}

		return false;
	}

	/**
	 * Joins string fragments using the specified separator
	 * 
	 * @param separator
	 * @param fragments
	 * @return combined fragments
	 */
	public static String join(String separator, String[] fragments)
	{
		if (fragments.length < 1)
		{
			// no elements
			return "";
		}
		else if (fragments.length < 2)
		{
			// single element
			return fragments[0];
		}
		else
		{
			// two or more elements
			StringBuffer buff = new StringBuffer(128);
			if (fragments[0] != null)
			{
				buff.append(fragments[0]);
			}
			for (int i = 1; i < fragments.length; i++)
			{
				if ((fragments[i - 1] != null) || (fragments[i] != null))
				{
					boolean lhsClosed = fragments[i - 1].endsWith(separator);
					boolean rhsClosed = fragments[i].startsWith(separator);
					if (lhsClosed && rhsClosed)
					{
						buff.append(fragments[i].substring(1));
					}
					else if (!lhsClosed && !rhsClosed)
					{
						buff.append(separator).append(fragments[i]);
					}
					else
					{
						buff.append(fragments[i]);
					}
				}
			}
			return buff.toString();
		}
	}

	/**
	 * Gets the last path component of a path using a given separator. If the separator cannot be
	 * found, the path itself is returned.
	 * <p>
	 * For example, lastPathComponent("foo.bar", '.') would return "bar" and
	 * lastPathComponent("foo", '.') would return "foo".
	 * 
	 * @param path
	 *            The path to parse
	 * @param separator
	 *            The path separator character
	 * @return The last component in the path or path itself if no separator characters exist.
	 */
	public static String lastPathComponent(final String path, final char separator)
	{
		if (path == null)
		{
			return null;
		}

		final int index = path.lastIndexOf(separator);

		if (index == -1)
		{
			return path;
		}

		return path.substring(index + 1);
	}

	/**
	 * Replace all occurrences of one string replaceWith another string.
	 * 
	 * @param s
	 *            The string to process
	 * @param searchFor
	 *            The value to search for
	 * @param replaceWith
	 *            The value to searchFor replaceWith
	 * @return The resulting string with searchFor replaced with replaceWith
	 */
	public static CharSequence replaceAll(final CharSequence s, final CharSequence searchFor,
			CharSequence replaceWith)
	{
		if (s == null)
		{
			return null;
		}

		// If searchFor is null or the empty string, then there is nothing to
		// replace, so returning s is the only option here.
		if (searchFor == null || "".equals(searchFor))
		{
			return s;
		}

		// If replaceWith is null, then the searchFor should be replaced with
		// nothing, which can be seen as the empty string.
		if (replaceWith == null)
		{
			replaceWith = "";
		}

		String searchString = searchFor.toString();
		// Look for first occurrence of searchFor
		int matchIndex = search(s, searchString, 0);
		if (matchIndex == -1)
		{
			// No replace operation needs to happen
			return s;
		}
		else
		{
			// Allocate a AppendingStringBuffer that will hold one replacement
			// with a
			// little extra room.
			int size = s.length();
			final int replaceWithLength = replaceWith.length();
			final int searchForLength = searchFor.length();
			if (replaceWithLength > searchForLength)
			{
				size += (replaceWithLength - searchForLength);
			}
			final AppendingStringBuffer buffer = new AppendingStringBuffer(size + 16);

			int pos = 0;
			do
			{
				// Append text up to the match`
				append(buffer, s, pos, matchIndex);

				// Add replaceWith text
				buffer.append(replaceWith);

				// Find next occurrence, if any
				pos = matchIndex + searchForLength;
				matchIndex = search(s, searchString, pos);
			}
			while (matchIndex != -1);

			// Add tail of s
			buffer.append(s.subSequence(pos, s.length()));

			// Return processed buffer
			return buffer;
		}
	}

	/**
	 * Replace HTML numbers like &#20540 by the appropriate character.
	 * 
	 * @param str
	 *            The text to be evaluated
	 * @return The text with "numbers" replaced
	 */
	public static String replaceHtmlEscapeNumber(String str)
	{
		if (str == null)
		{
			return null;
		}
		Matcher matcher = htmlNumber.matcher(str);
		while (matcher.find())
		{
			int pos = matcher.start();
			int end = matcher.end();
			int number = Integer.parseInt(str.substring(pos + 2, end - 1));
			char ch = (char)number;
			str = str.substring(0, pos) + ch + str.substring(end);
			matcher = htmlNumber.matcher(str);
		}

		return str;
	}

	/**
	 * Simpler, faster version of String.split() for splitting on a simple character.
	 * 
	 * @param s
	 *            The string to split
	 * @param c
	 *            The character to split on
	 * @return The array of strings
	 */
	public static String[] split(final String s, final char c)
	{
		if (s == null)
		{
			return new String[0];
		}
		final List strings = new ArrayList();
		int pos = 0;
		while (true)
		{
			int next = s.indexOf(c, pos);
			if (next == -1)
			{
				strings.add(s.substring(pos));
				break;
			}
			else
			{
				strings.add(s.substring(pos, next));
			}
			pos = next + 1;
		}
		final String[] result = new String[strings.size()];
		strings.toArray(result);
		return result;
	}

	/**
	 * Strips the ending from the string <code>s</code>.
	 * 
	 * @param s
	 *            The string to strip
	 * @param ending
	 *            The ending to strip off
	 * @return The stripped string or the original string if the ending did not exist
	 */
	public static String stripEnding(final String s, final String ending)
	{
		if (s == null)
		{
			return null;
		}

		// Stripping a null or empty string from the end returns the
		// original string.
		if (ending == null || "".equals(ending))
		{
			return s;
		}
		final int endingLength = ending.length();
		final int sLength = s.length();

		// When the length of the ending string is larger
		// than the original string, the original string is returned.
		if (endingLength > sLength)
		{
			return s;
		}
		final int index = s.lastIndexOf(ending);
		final int endpos = sLength - endingLength;

		if (index == endpos)
		{
			return s.substring(0, endpos);
		}

		return s;
	}

	/**
	 * Strip any jsessionid and possibly other redundant info that might be in our way.
	 * 
	 * @param url
	 *            The url to strip
	 * @return The stripped url
	 */
	public static String stripJSessionId(CharSequence url)
	{
		if (url == null)
		{
			return null;
		}
		StringBuffer path = new StringBuffer(url.toString());
		int ixSemiColon = path.indexOf(";");
		// strip off any jsession id
		if (ixSemiColon != -1)
		{
			int ixEnd = path.indexOf("?");
			if (ixEnd == -1)
			{
				ixEnd = path.length();
			}
			path.delete(ixSemiColon, ixEnd);
		}
		return path.toString();