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Java Source Code / Java Documentation  » 6.0 JDK Core » Collections Jar Zip Logging regex » java.util 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


        /*
         * Copyright 1995-2006 Sun Microsystems, Inc.  All Rights Reserved.
         * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
         *
         * This code is free software; you can redistribute it and/or modify it
         * under the terms of the GNU General Public License version 2 only, as
         * published by the Free Software Foundation.  Sun designates this
         * particular file as subject to the "Classpath" exception as provided
         * by Sun in the LICENSE file that accompanied this code.
         *
         * This code is distributed in the hope that it will be useful, but WITHOUT
         * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
         * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
         * version 2 for more details (a copy is included in the LICENSE file that
         * accompanied this code).
         *
         * You should have received a copy of the GNU General Public License version
         * 2 along with this work; if not, write to the Free Software Foundation,
         * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
         *
         * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
         * CA 95054 USA or visit www.sun.com if you need additional information or
         * have any questions.
         */

        package java.util;

        import java.io.IOException;
        import java.io.PrintStream;
        import java.io.PrintWriter;
        import java.io.InputStream;
        import java.io.OutputStream;
        import java.io.Reader;
        import java.io.Writer;
        import java.io.OutputStreamWriter;
        import java.io.BufferedWriter;

        /**
         * The <code>Properties</code> class represents a persistent set of
         * properties. The <code>Properties</code> can be saved to a stream
         * or loaded from a stream. Each key and its corresponding value in
         * the property list is a string.
         * <p>
         * A property list can contain another property list as its
         * "defaults"; this second property list is searched if
         * the property key is not found in the original property list.
         * <p>
         * Because <code>Properties</code> inherits from <code>Hashtable</code>, the
         * <code>put</code> and <code>putAll</code> methods can be applied to a
         * <code>Properties</code> object.  Their use is strongly discouraged as they
         * allow the caller to insert entries whose keys or values are not
         * <code>Strings</code>.  The <code>setProperty</code> method should be used
         * instead.  If the <code>store</code> or <code>save</code> method is called
         * on a "compromised" <code>Properties</code> object that contains a
         * non-<code>String</code> key or value, the call will fail. Similarly, 
         * the call to the <code>propertyNames</code> or <code>list</code> method 
         * will fail if it is called on a "compromised" <code>Properties</code> 
         * object that contains a non-<code>String</code> key.
         *
         * <p>
         * The {@link #load(java.io.Reader) load(Reader)} <tt>/</tt>
         * {@link #store(java.io.Writer, java.lang.String) store(Writer, String)}
         * methods load and store properties from and to a character based stream
         * in a simple line-oriented format specified below.
         *
         * The {@link #load(java.io.InputStream) load(InputStream)} <tt>/</tt>
         * {@link #store(java.io.OutputStream, java.lang.String) store(OutputStream, String)}
         * methods work the same way as the load(Reader)/store(Writer, String) pair, except
         * the input/output stream is encoded in ISO 8859-1 character encoding.
         * Characters that cannot be directly represented in this encoding can be written using
         * <a href="http://java.sun.com/docs/books/jls/third_edition/html/lexical.html#3.3">Unicode escapes</a>
         * ; only a single 'u' character is allowed in an escape
         * sequence. The native2ascii tool can be used to convert property files to and
         * from other character encodings.
         * 
         * <p> The {@link #loadFromXML(InputStream)} and {@link
         * #storeToXML(OutputStream, String, String)} methods load and store properties
         * in a simple XML format.  By default the UTF-8 character encoding is used,
         * however a specific encoding may be specified if required.  An XML properties
         * document has the following DOCTYPE declaration:
         *
         * <pre>
         * &lt;!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd"&gt;
         * </pre>
         * Note that the system URI (http://java.sun.com/dtd/properties.dtd) is
         * <i>not</i> accessed when exporting or importing properties; it merely
         * serves as a string to uniquely identify the DTD, which is:
         * <pre>
         *    &lt;?xml version="1.0" encoding="UTF-8"?&gt;
         *
         *    &lt;!-- DTD for properties --&gt;
         *
         *    &lt;!ELEMENT properties ( comment?, entry* ) &gt;
         *
         *    &lt;!ATTLIST properties version CDATA #FIXED "1.0"&gt;
         *
         *    &lt;!ELEMENT comment (#PCDATA) &gt;
         *
         *    &lt;!ELEMENT entry (#PCDATA) &gt;
         *
         *    &lt;!ATTLIST entry key CDATA #REQUIRED&gt;
         * </pre>
         * 
         * @see <a href="../../../technotes/tools/solaris/native2ascii.html">native2ascii tool for Solaris</a>
         * @see <a href="../../../technotes/tools/windows/native2ascii.html">native2ascii tool for Windows</a>
         *
         * <p>This class is thread-safe: multiple threads can share a single
         * <tt>Properties</tt> object without the need for external synchronization.
         *
         * @author  Arthur van Hoff
         * @author  Michael McCloskey
         * @author  Xueming Shen
         * @version 1.102, 05/05/07
         * @since   JDK1.0
         */
        public class Properties extends Hashtable<Object, Object> {
            /**
             * use serialVersionUID from JDK 1.1.X for interoperability
             */
            private static final long serialVersionUID = 4112578634029874840L;

            /**
             * A property list that contains default values for any keys not
             * found in this property list.
             *
             * @serial
             */
            protected Properties defaults;

            /**
             * Creates an empty property list with no default values.
             */
            public Properties() {
                this (null);
            }

            /**
             * Creates an empty property list with the specified defaults.
             *
             * @param   defaults   the defaults.
             */
            public Properties(Properties defaults) {
                this .defaults = defaults;
            }

            /**
             * Calls the <tt>Hashtable</tt> method <code>put</code>. Provided for
             * parallelism with the <tt>getProperty</tt> method. Enforces use of
             * strings for property keys and values. The value returned is the
             * result of the <tt>Hashtable</tt> call to <code>put</code>.
             *
             * @param key the key to be placed into this property list.
             * @param value the value corresponding to <tt>key</tt>.
             * @return     the previous value of the specified key in this property
             *             list, or <code>null</code> if it did not have one.
             * @see #getProperty
             * @since    1.2
             */
            public synchronized Object setProperty(String key, String value) {
                return put(key, value);
            }

            /**
             * Reads a property list (key and element pairs) from the input
             * character stream in a simple line-oriented format.
             * <p>
             * Properties are processed in terms of lines. There are two
             * kinds of line, <i>natural lines</i> and <i>logical lines</i>.
             * A natural line is defined as a line of
             * characters that is terminated either by a set of line terminator
             * characters (<code>\n</code> or <code>\r</code> or <code>\r\n</code>)
             * or by the end of the stream. A natural line may be either a blank line,
             * a comment line, or hold all or some of a key-element pair. A logical
             * line holds all the data of a key-element pair, which may be spread
             * out across several adjacent natural lines by escaping
             * the line terminator sequence with a backslash character
             * <code>\</code>.  Note that a comment line cannot be extended
             * in this manner; every natural line that is a comment must have
             * its own comment indicator, as described below. Lines are read from
             * input until the end of the stream is reached.
             *
             * <p>
             * A natural line that contains only white space characters is
             * considered blank and is ignored.  A comment line has an ASCII
             * <code>'#'</code> or <code>'!'</code> as its first non-white
             * space character; comment lines are also ignored and do not
             * encode key-element information.  In addition to line
             * terminators, this format considers the characters space
             * (<code>' '</code>, <code>'&#92;u0020'</code>), tab
             * (<code>'\t'</code>, <code>'&#92;u0009'</code>), and form feed
             * (<code>'\f'</code>, <code>'&#92;u000C'</code>) to be white
             * space.
             *
             * <p>
             * If a logical line is spread across several natural lines, the
             * backslash escaping the line terminator sequence, the line
             * terminator sequence, and any white space at the start of the
             * following line have no affect on the key or element values.
             * The remainder of the discussion of key and element parsing
             * (when loading) will assume all the characters constituting
             * the key and element appear on a single natural line after
             * line continuation characters have been removed.  Note that
             * it is <i>not</i> sufficient to only examine the character
             * preceding a line terminator sequence to decide if the line
             * terminator is escaped; there must be an odd number of
             * contiguous backslashes for the line terminator to be escaped.
             * Since the input is processed from left to right, a
             * non-zero even number of 2<i>n</i> contiguous backslashes
             * before a line terminator (or elsewhere) encodes <i>n</i>
             * backslashes after escape processing.
             *
             * <p>
             * The key contains all of the characters in the line starting
             * with the first non-white space character and up to, but not
             * including, the first unescaped <code>'='</code>,
             * <code>':'</code>, or white space character other than a line
             * terminator. All of these key termination characters may be
             * included in the key by escaping them with a preceding backslash
             * character; for example,<p>
             *
             * <code>\:\=</code><p>
             *
             * would be the two-character key <code>":="</code>.  Line
             * terminator characters can be included using <code>\r</code> and
             * <code>\n</code> escape sequences.  Any white space after the
             * key is skipped; if the first non-white space character after
             * the key is <code>'='</code> or <code>':'</code>, then it is
             * ignored and any white space characters after it are also
             * skipped.  All remaining characters on the line become part of
             * the associated element string; if there are no remaining
             * characters, the element is the empty string
             * <code>&quot;&quot;</code>.  Once the raw character sequences
             * constituting the key and element are identified, escape
             * processing is performed as described above.
             *
             * <p>
             * As an example, each of the following three lines specifies the key
             * <code>"Truth"</code> and the associated element value
             * <code>"Beauty"</code>:
             * <p>
             * <pre>
             * Truth = Beauty
             *	Truth:Beauty
             * Truth			:Beauty
             * </pre>
             * As another example, the following three lines specify a single
             * property:
             * <p>
             * <pre>
             * fruits                           apple, banana, pear, \
             *                                  cantaloupe, watermelon, \
             *                                  kiwi, mango
             * </pre>
             * The key is <code>"fruits"</code> and the associated element is:
             * <p>
             * <pre>"apple, banana, pear, cantaloupe, watermelon, kiwi, mango"</pre>
             * Note that a space appears before each <code>\</code> so that a space
             * will appear after each comma in the final result; the <code>\</code>,
             * line terminator, and leading white space on the continuation line are
             * merely discarded and are <i>not</i> replaced by one or more other
             * characters.
             * <p>
             * As a third example, the line:
             * <p>
             * <pre>cheeses
             * </pre>
             * specifies that the key is <code>"cheeses"</code> and the associated
             * element is the empty string <code>""</code>.<p>
             * <p>
             *
             * <a name="unicodeescapes"></a>
             * Characters in keys and elements can be represented in escape
             * sequences similar to those used for character and string literals
             * (see <a
             * href="http://java.sun.com/docs/books/jls/third_edition/html/lexical.html#3.3">&sect;3.3</a>
             * and <a
             * href="http://java.sun.com/docs/books/jls/third_edition/html/lexical.html#3.10.6">&sect;3.10.6</a>
             * of the <i>Java Language Specification</i>).
             *
             * The differences from the character escape sequences and Unicode
             * escapes used for characters and strings are:
             *
             * <ul>
             * <li> Octal escapes are not recognized.
             *
             * <li> The character sequence <code>\b</code> does <i>not</i>
             * represent a backspace character.
             *
             * <li> The method does not treat a backslash character,
             * <code>\</code>, before a non-valid escape character as an
             * error; the backslash is silently dropped.  For example, in a
             * Java string the sequence <code>"\z"</code> would cause a
             * compile time error.  In contrast, this method silently drops
             * the backslash.  Therefore, this method treats the two character
             * sequence <code>"\b"</code> as equivalent to the single
             * character <code>'b'</code>.
             *
             * <li> Escapes are not necessary for single and double quotes;
             * however, by the rule above, single and double quote characters
             * preceded by a backslash still yield single and double quote
             * characters, respectively.
             *
             * <li> Only a single 'u' character is allowed in a Uniocde escape
             * sequence.
             *
             * </ul>
             * <p>
             * The specified stream remains open after this method returns.
             *
             * @param   reader   the input character stream.
             * @throws  IOException  if an error occurred when reading from the
             *          input stream.
             * @throws  IllegalArgumentException if a malformed Unicode escape
             *          appears in the input.
             * @since   1.6
             */
            public synchronized void load(Reader reader) throws IOException {
                load0(new LineReader(reader));
            }

            /**
             * Reads a property list (key and element pairs) from the input
             * byte stream. The input stream is in a simple line-oriented
             * format as specified in
             * {@link #load(java.io.Reader) load(Reader)} and is assumed to use
             * the ISO 8859-1 character encoding; that is each byte is one Latin1
             * character. Characters not in Latin1, and certain special characters,
             * are represented in keys and elements using
             * <a href="http://java.sun.com/docs/books/jls/third_edition/html/lexical.html#3.3">Unicode escapes</a>.
             * <p>
             * The specified stream remains open after this method returns.
             *
             * @param      inStream   the input stream.
             * @exception  IOException  if an error occurred when reading from the
             *             input stream.
             * @throws	   IllegalArgumentException if the input stream contains a
             * 		   malformed Unicode escape sequence.
             * @since 1.2
             */
            public synchronized void load(InputStream inStream)
                    throws IOException {
                load0(new LineReader(inStream));
            }

            private void load0(LineReader lr) throws IOException {
                char[] convtBuf = new char[1024];
                int limit;
                int keyLen;
                int valueStart;
                char c;
                boolean hasSep;
                boolean precedingBackslash;

                while ((limit = lr.readLine()) >= 0) {
                    c = 0;
                    keyLen = 0;
                    valueStart = limit;
                    hasSep = false;

                    //System.out.println("line=<" + new String(lineBuf, 0, limit) + ">");
                    precedingBackslash = false;
                    while (keyLen < limit) {
                        c = lr.lineBuf[keyLen];
                        //need check if escaped.
                        if ((c == '=' || c == ':') && !precedingBackslash) {
                            valueStart = keyLen + 1;
                            hasSep = true;
                            break;
                        } else if ((c == ' ' || c == '\t' || c == '\f')
                                && !precedingBackslash) {
                            valueStart = keyLen + 1;
                            break;
                        }
                        if (c == '\\') {
                            precedingBackslash = !precedingBackslash;
                        } else {
                            precedingBackslash = false;
                        }
                        keyLen++;
                    }
                    while (valueStart < limit) {
                        c = lr.lineBuf[valueStart];
                        if (c != ' ' && c != '\t' && c != '\f') {
                            if (!hasSep && (c == '=' || c == ':')) {
                                hasSep = true;
                            } else {
                                break;
                            }
                        }
                        valueStart++;
                    }
                    String key = loadConvert(lr.lineBuf, 0, keyLen, convtBuf);
                    String value = loadConvert(lr.lineBuf, valueStart, limit
                            - valueStart, convtBuf);
                    put(key, value);
                }
            }

            /* Read in a "logical line" from an InputStream/Reader, skip all comment
             * and blank lines and filter out those leading whitespace characters 
             * (\u0020, \u0009 and \u000c) from the beginning of a "natural line". 
             * Method returns the char length of the "logical line" and stores 
             * the line in "lineBuf". 
             */
            class LineReader {
                public LineReader(InputStream inStream) {
                    this .inStream = inStream;
                    inByteBuf = new byte[8192];
                }

                public LineReader(Reader reader) {
                    this .reader = reader;
                    inCharBuf = new char[8192];
                }

                byte[] inByteBuf;
                char[] inCharBuf;
                char[] lineBuf = new char[1024];
                int inLimit = 0;
                int inOff = 0;
                InputStream inStream;
                Reader reader;

                int readLine() throws IOException {
                    int len = 0;
                    char c = 0;

                    boolean skipWhiteSpace = true;
                    boolean isCommentLine = false;
                    boolean isNewLine = true;
                    boolean appendedLineBegin = false;
                    boolean precedingBackslash = false;
                    boolean skipLF = false;

                    while (true) {
                        if (inOff >= inLimit) {
                            inLimit = (inStream == null) ? reader
                                    .read(inCharBuf) : inStream.read(inByteBuf);
                            inOff = 0;
                            if (inLimit <= 0) {
                                if (len == 0 || isCommentLine) {
                                    return -1;
                                }
                                return len;
                            }
                        }
                        if (inStream != null) {
                            //The line below is equivalent to calling a 
                            //ISO8859-1 decoder.
                            c = (char) (0xff & inByteBuf[inOff++]);
                        } else {
                            c = inCharBuf[inOff++];
                        }
                        if (skipLF) {
                            skipLF = false;
                            if (c == '\n') {
                                continue;
                            }
                        }
                        if (skipWhiteSpace) {
                            if (c == ' ' || c == '\t' || c == '\f') {
                                continue;
                            }
                            if (!appendedLineBegin && (c == '\r' || c == '\n')) {
                                continue;
                            }
                            skipWhiteSpace = false;
                            appendedLineBegin = false;
                        }
                        if (isNewLine) {
                            isNewLine = false;
                            if (c == '#' || c == '!') {
                                isCommentLine = true;
                                continue;
                            }
                        }

                        if (c != '\n' && c != '\r') {
                            lineBuf[len++] = c;
                            if (len == lineBuf.length) {
                                int newLength = lineBuf.length * 2;
                                if (newLength < 0) {
                                    newLength = Integer.MAX_VALUE;
                                }
                                char[] buf = new char[newLength];
                                System.arraycopy(lineBuf, 0, buf, 0,
                                        lineBuf.length);
                                lineBuf = buf;
                            }
                            //flip the preceding backslash flag
                            if (c == '\\') {
                                precedingBackslash = !precedingBackslash;
                            } else {
                                precedingBackslash = false;
                            }
                        } else {
                            // reached EOL
                            if (isCommentLine || len == 0) {
                                isCommentLine = false;
                                isNewLine = true;
                                skipWhiteSpace = true;
                                len = 0;
                                continue;
                            }
                            if (inOff >= inLimit) {
                                inLimit = (inStream == null) ? reader
                                        .read(inCharBuf) : inStream
                                        .read(inByteBuf);
                                inOff = 0;
                                if (inLimit <= 0) {
                                    return len;
                                }
                            }
                            if (precedingBackslash) {
                                len -= 1;
                                //skip the leading whitespace characters in following line
                                skipWhiteSpace = true;
                                appendedLineBegin = true;
                                precedingBackslash = false;
                                if (c == '\r') {
                                    skipLF = true;
                                }
                            } else {
                                return len;
                            }
                        }
                    }
                }
            }

            /*
             * Converts encoded &#92;uxxxx to unicode chars
             * and changes special saved chars to their original forms
             */
            private String loadConvert(char[] in, int off, int len,
                    char[] convtBuf) {
                if (convtBuf.length < len) {
                    int newLen = len * 2;
                    if (newLen < 0) {
                        newLen = Integer.MAX_VALUE;
                    }
                    convtBuf = new char[newLen];
                }
                char aChar;
                char[] out = convtBuf;
                int outLen = 0;
                int end = off + len;

                while (off < end) {
                    aChar = in[off++];
                    if (aChar == '\\') {
                        aChar = in[off++];
                        if (aChar == 'u') {
                            // 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++] = (char) aChar;
                    }
                }
                return new String(out, 0, outLen);
            }

            /*
             * Converts unicodes to encoded &#92;uxxxx and escapes
             * special characters with a preceding slash
             */
            private String saveConvert(String theString, boolean escapeSpace,
                    boolean escapeUnicode) {
                int len = theString.length();
                int bufLen = len * 2;
                if (bufLen < 0) {
                    bufLen = Integer.MAX_VALUE;
                }
                StringBuffer outBuffer = new StringBuffer(bufLen);

                for (int x = 0; x < len; x++) {
                    char aChar = theString.charAt(x);
                    // Handle common case first, selecting largest block that
                    // avoids the specials below
                    if ((aChar > 61) && (aChar < 127)) {
                        if (aChar == '\\') {
                            outBuffer.append('\\');
                            outBuffer.append('\\');
                            continue;
                        }
                        outBuffer.append(aChar);
                        continue;
                    }
                    switch (aChar) {
                    case ' ':
                        if (x == 0 || escapeSpace)
                            outBuffer.append('\\');
                        outBuffer.append(' ');
                        break;
                    case '\t':
                        outBuffer.append('\\');
                        outBuffer.append('t');
                        break;
                    case '\n':
                        outBuffer.append('\\');
                        outBuffer.append('n');
                        break;
                    case '\r':
                        outBuffer.append('\\');
                        outBuffer.append('r');
                        break;
                    case '\f':
                        outBuffer.append('\\');
                        outBuffer.append('f');
                        break;
                    case '=': // Fall through
                    case ':': // Fall through
                    case '#': // Fall through
                    case '!':
                        outBuffer.append('\\');
                        outBuffer.append(aChar);
                        break;
                    default:
                        if (((aChar < 0x0020) || (aChar > 0x007e))
                                & escapeUnicode) {
                            outBuffer.append('\\');
                            outBuffer.append('u');
                            outBuffer.append(toHex((aChar >> 12) & 0xF));
                            outBuffer.append(toHex((aChar >> 8) & 0xF));
                            outBuffer.append(toHex((aChar >> 4) & 0xF));
                            outBuffer.append(toHex(aChar & 0xF));
                        } else {
                            outBuffer.append(aChar);
                        }
                    }
                }
                return outBuffer.toString();
            }

            private static void writeComments(BufferedWriter bw, String comments)
                    throws IOException {
                bw.write("#");
                int len = comments.length();
                int current = 0;
                int last = 0;
                char[] uu = new char[6];
                uu[0] = '\\';
                uu[1] = 'u';
                while (current < len) {
                    char c = comments.charAt(current);
                    if (c > '\u00ff' || c == '\n' || c == '\r') {
                        if (last != current)
                            bw.write(comments.substring(last, current));
                        if (c > '\u00ff') {
                            uu[2] = toHex((c >> 12) & 0xf);
                            uu[3] = toHex((c >> 8) & 0xf);
                            uu[4] = toHex((c >> 4) & 0xf);
                            uu[5] = toHex(c & 0xf);
                            bw.write(new String(uu));
                        } else {
                            bw.newLine();
                            if (c == '\r' && current != len - 1
                                    && comments.charAt(current + 1) == '\n') {
                                current++;
                            }
                            if (current == len - 1
                                    || (comments.charAt(current + 1) != '#' && comments
                                            .charAt(current + 1) != '!'))
                                bw.write("#");
                        }
                        last = current + 1;
                    }
                    current++;
                }
                if (last != current)
                    bw.write(comments.substring(last, current));
                bw.newLine();
            }

            /**
             * Calls the <code>store(OutputStream out, String comments)</code> method
             * and suppresses IOExceptions that were thrown.
             *
             * @deprecated This method does not throw an IOException if an I/O error
             * occurs while saving the property list.  The preferred way to save a
             * properties list is via the <code>store(OutputStream out, 
             * String comments)</code> method or the 
             * <code>storeToXML(OutputStream os, String comment)</code> method.
             *
             * @param   out      an output stream.
             * @param   comments   a description of the property list.
             * @exception  ClassCastException  if this <code>Properties</code> object
             *             contains any keys or values that are not 
             *             <code>Strings</code>.
             */
            @Deprecated
            public synchronized void save(OutputStream out, String comments) {
                try {
                    store(out, comments);
                } catch (IOException e) {
                }
            }

            /**
             * Writes this property list (key and element pairs) in this
             * <code>Properties</code> table to the output character stream in a 
             * format suitable for using the {@link #load(java.io.Reader) load(Reader)}
             * method.
             * <p>
             * Properties from the defaults table of this <code>Properties</code>
             * table (if any) are <i>not</i> written out by this method.
             * <p>
             * If the comments argument is not null, then an ASCII <code>#</code>
             * character, the comments string, and a line separator are first written
             * to the output stream. Thus, the <code>comments</code> can serve as an
             * identifying comment. Any one of a line feed ('\n'), a carriage
             * return ('\r'), or a carriage return followed immediately by a line feed
             * in comments is replaced by a line separator generated by the <code>Writer</code>
             * and if the next character in comments is not character <code>#</code> or 
             * character <code>!</code> then an ASCII <code>#</code> is written out 
             * after that line separator.
             * <p>
             * Next, a comment line is always written, consisting of an ASCII
             * <code>#</code> character, the current date and time (as if produced
             * by the <code>toString</code> method of <code>Date</code> for the
             * current time), and a line separator as generated by the <code>Writer</code>.
             * <p>
             * Then every entry in this <code>Properties</code> table is
             * written out, one per line. For each entry the key string is
             * written, then an ASCII <code>=</code>, then the associated
             * element string. For the key, all space characters are
             * written with a preceding <code>\</code> character.  For the
             * element, leading space characters, but not embedded or trailing
             * space characters, are written with a preceding <code>\</code>
             * character. The key and element characters <code>#</code>,
             * <code>!</code>, <code>=</code>, and <code>:</code> are written
             * with a preceding backslash to ensure that they are properly loaded.
             * <p>
             * After the entries have been written, the output stream is flushed.  
             * The output stream remains open after this method returns.
             * <p>
             *
             * @param   writer      an output character stream writer.
             * @param   comments   a description of the property list.
             * @exception  IOException if writing this property list to the specified
             *             output stream throws an <tt>IOException</tt>.
             * @exception  ClassCastException  if this <code>Properties</code> object
             *             contains any keys or values that are not <code>Strings</code>.
             * @exception  NullPointerException  if <code>writer</code> is null.
             * @since 1.6
             */
            public void store(Writer writer, String comments)
                    throws IOException {
                store0(
                        (writer instanceof  BufferedWriter) ? (BufferedWriter) writer
                                : new BufferedWriter(writer), comments, false);
            }

            /**
             * Writes this property list (key and element pairs) in this
             * <code>Properties</code> table to the output stream in a format suitable
             * for loading into a <code>Properties</code> table using the
             * {@link #load(InputStream) load(InputStream)} method.
             * <p>
             * Properties from the defaults table of this <code>Properties</code>
             * table (if any) are <i>not</i> written out by this method.
             * <p>
             * This method outputs the comments, properties keys and values in 
             * the same format as specified in
             * {@link #store(java.io.Writer, java.lang.String) store(Writer)},
             * with the following differences:
             * <ul>
             * <li>The stream is written using the ISO 8859-1 character encoding.
             *
             * <li>Characters not in Latin-1 in the comments are written as 
             * <code>&#92;u</code><i>xxxx</i> for their appropriate unicode 
             * hexadecimal value <i>xxxx</i>. 
             * 
             * <li>Characters less than <code>&#92;u0020</code> and characters greater
             * than <code>&#92;u007E</code> in property keys or values are written
             * as <code>&#92;u</code><i>xxxx</i> for the appropriate hexadecimal
             * value <i>xxxx</i>. 
             * </ul>
             * <p>
             * After the entries have been written, the output stream is flushed.  
             * The output stream remains open after this method returns.
             * <p>
             * @param   out      an output stream.
             * @param   comments   a description of the property list.
             * @exception  IOException if writing this property list to the specified
             *             output stream throws an <tt>IOException</tt>.
             * @exception  ClassCastException  if this <code>Properties</code> object
             *             contains any keys or values that are not <code>Strings</code>.
             * @exception  NullPointerException  if <code>out</code> is null.
             * @since 1.2
             */
            public void store(OutputStream out, String comments)
                    throws IOException {
                store0(
                        new BufferedWriter(
                                new OutputStreamWriter(out, "8859_1")),
                        comments, true);
            }

            private void store0(BufferedWriter bw, String comments,
                    boolean escUnicode) throws IOException {
                if (comments != null) {
                    writeComments(bw, comments);
                }
                bw.write("#" + new Date().toString());
                bw.newLine();
                synchronized (this ) {
                    for (Enumeration e = keys(); e.hasMoreElements();) {
                        String key = (String) e.nextElement();
                        String val = (String) get(key);
                        key = saveConvert(key, true, escUnicode);
                        /* No need to escape embedded and trailing spaces for value, hence
                         * pass false to flag.
                         */
                        val = saveConvert(val, false, escUnicode);
                        bw.write(key + "=" + val);
                        bw.newLine();
                    }
                }
                bw.flush();
            }

            /**
             * Loads all of the properties represented by the XML document on the
             * specified input stream into this properties table.
             *
             * <p>The XML document must have the following DOCTYPE declaration:
             * <pre>
             * &lt;!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd"&gt;
             * </pre>
             * Furthermore, the document must satisfy the properties DTD described
             * above.
             *
             * <p>The specified stream is closed after this method returns.
             *
             * @param in the input stream from which to read the XML document.
             * @throws IOException if reading from the specified input stream
             *         results in an <tt>IOException</tt>.
             * @throws InvalidPropertiesFormatException Data on input stream does not
             *         constitute a valid XML document with the mandated document type.
             * @throws NullPointerException if <code>in</code> is null.
             * @see    #storeToXML(OutputStream, String, String)
             * @since 1.5
             */
            public synchronized void loadFromXML(InputStream in)
                    throws IOException, InvalidPropertiesFormatException {
                if (in == null)
                    throw new NullPointerException();
                XMLUtils.load(this , in);
                in.close();
            }

            /**
             * Emits an XML document representing all of the properties contained
             * in this table.
             *
             * <p> An invocation of this method of the form <tt>props.storeToXML(os,
             * comment)</tt> behaves in exactly the same way as the invocation
             * <tt>props.storeToXML(os, comment, "UTF-8");</tt>.
             *
             * @param os the output stream on which to emit the XML document.
             * @param comment a description of the property list, or <code>null</code>
             *        if no comment is desired.
             * @throws IOException if writing to the specified output stream
             *         results in an <tt>IOException</tt>.
             * @throws NullPointerException if <code>os</code> is null.
             * @throws ClassCastException  if this <code>Properties</code> object
             *         contains any keys or values that are not 
             *         <code>Strings</code>.
             * @see    #loadFromXML(InputStream)
             * @since 1.5
             */
            public synchronized void storeToXML(OutputStream os, String comment)
                    throws IOException {
                if (os == null)
                    throw new NullPointerException();
                storeToXML(os, comment, "UTF-8");
            }

            /**
             * Emits an XML document representing all of the properties contained
             * in this table, using the specified encoding.
             *
             * <p>The XML document will have the following DOCTYPE declaration:
             * <pre>
             * &lt;!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd"&gt;
             * </pre>
             *
             *<p>If the specified comment is <code>null</code> then no comment
             * will be stored in the document.
             *
             * <p>The specified stream remains open after this method returns.
             *
             * @param os the output stream on which to emit the XML document.
             * @param comment a description of the property list, or <code>null</code>
             *        if no comment is desired.
             * @throws IOException if writing to the specified output stream
             *         results in an <tt>IOException</tt>.
             * @throws NullPointerException if <code>os</code> is <code>null</code>,
             *         or if <code>encoding</code> is <code>null</code>.
             * @throws ClassCastException  if this <code>Properties</code> object
             *         contains any keys or values that are not 
             *         <code>Strings</code>.
             * @see    #loadFromXML(InputStream)
             * @since 1.5
             */
            public synchronized void storeToXML(OutputStream os,
                    String comment, String encoding) throws IOException {
                if (os == null)
                    throw new NullPointerException();
                XMLUtils.save(this , os, comment, encoding);
            }

            /**
             * Searches for the property with the specified key in this property list.
             * If the key is not found in this property list, the default property list,
             * and its defaults, recursively, are then checked. The method returns
             * <code>null</code> if the property is not found.
             *
             * @param   key   the property key.
             * @return  the value in this property list with the specified key value.
             * @see     #setProperty
             * @see     #defaults
             */
            public String getProperty(String key) {
                Object oval = super .get(key);
                String sval = (oval instanceof  String) ? (String) oval : null;
                return ((sval == null) && (defaults != null)) ? defaults
                        .getProperty(key) : sval;
            }

            /**
             * Searches for the property with the specified key in this property list.
             * If the key is not found in this property list, the default property list,
             * and its defaults, recursively, are then checked. The method returns the
             * default value argument if the property is not found.
             *
             * @param   key            the hashtable key.
             * @param   defaultValue   a default value.
             *
             * @return  the value in this property list with the specified key value.
             * @see     #setProperty
             * @see     #defaults
             */
            public String getProperty(String key, String defaultValue) {
                String val = getProperty(key);
                return (val == null) ? defaultValue : val;
            }

            /**
             * Returns an enumeration of all the keys in this property list,
             * including distinct keys in the default property list if a key
             * of the same name has not already been found from the main
             * properties list.
             *
             * @return  an enumeration of all the keys in this property list, including
             *          the keys in the default property list.
             * @throws  ClassCastException if any key in this property list
             *          is not a string. 
             * @see     java.util.Enumeration
             * @see     java.util.Properties#defaults
             * @see     #stringPropertyNames
             */
            public Enumeration<?> propertyNames() {
                Hashtable h = new Hashtable();
                enumerate(h);
                return h.keys();
            }

            /**
             * Returns a set of keys in this property list where
             * the key and its corresponding value are strings,
             * including distinct keys in the default property list if a key
             * of the same name has not already been found from the main
             * properties list.  Properties whose key or value is not 
             * of type <tt>String</tt> are omitted.
             * <p>
             * The returned set is not backed by the <tt>Properties</tt> object.
             * Changes to this <tt>Properties</tt> are not reflected in the set,
             * or vice versa.
             *
             * @return  a set of keys in this property list where
             *          the key and its corresponding value are strings,
             *          including the keys in the default property list.
             * @see     java.util.Properties#defaults
             * @since   1.6
             */
            public Set<String> stringPropertyNames() {
                Hashtable<String, String> h = new Hashtable<String, String>();
                enumerateStringProperties(h);
                return h.keySet();
            }

            /**
             * Prints this property list out to the specified output stream.
             * This method is useful for debugging.
             *
             * @param   out   an output stream.
             * @throws  ClassCastException if any key in this property list
             *          is not a string. 
             */
            public void list(PrintStream out) {
                out.println("-- listing properties --");
                Hashtable h = new Hashtable();
                enumerate(h);
                for (Enumeration e = h.keys(); e.hasMoreElements();) {
                    String key = (String) e.nextElement();
                    String val = (String) h.get(key);
                    if (val.length() > 40) {
                        val = val.substring(0, 37) + "...";
                    }
                    out.println(key + "=" + val);
                }
            }

            /**
             * Prints this property list out to the specified output stream.
             * This method is useful for debugging.
             *
             * @param   out   an output stream.
             * @throws  ClassCastException if any key in this property list
             *          is not a string. 
             * @since   JDK1.1
             */
            /*
             * Rather than use an anonymous inner class to share common code, this
             * method is duplicated in order to ensure that a non-1.1 compiler can
             * compile this file.
             */
            public void list(PrintWriter out) {
                out.println("-- listing properties --");
                Hashtable h = new Hashtable();
                enumerate(h);
                for (Enumeration e = h.keys(); e.hasMoreElements();) {
                    String key = (String) e.nextElement();
                    String val = (String) h.get(key);
                    if (val.length() > 40) {
                        val = val.substring(0, 37) + "...";
                    }
                    out.println(key + "=" + val);
                }
            }

            /**
             * Enumerates all key/value pairs in the specified hashtable.
             * @param h the hashtable
             * @throws ClassCastException if any of the property keys
             *         is not of String type.
             */
            private synchronized void enumerate(Hashtable h) {
                if (defaults != null) {
                    defaults.enumerate(h);
                }
                for (Enumeration e = keys(); e.hasMoreElements();) {
                    String key = (String) e.nextElement();
                    h.put(key, get(key));
                }
            }

            /**
             * Enumerates all key/value pairs in the specified hashtable
             * and omits the property if the key or value is not a string.
             * @param h the hashtable
             */
            private synchronized void enumerateStringProperties(
                    Hashtable<String, String> h) {
                if (defaults != null) {
                    defaults.enumerateStringProperties(h);
                }
                for (Enumeration e = keys(); e.hasMoreElements();) {
                    Object k = e.nextElement();
                    Object v = get(k);
                    if (k instanceof  String && v instanceof  String) {
                        h.put((String) k, (String) v);
                    }
                }
            }

            /**
             * Convert a nibble to a hex character
             * @param	nibble	the nibble to convert.
             */
            private static char toHex(int nibble) {
                return hexDigit[(nibble & 0xF)];
            }

            /** A table of hex digits */
            private static final char[] hexDigit = { '0', '1', '2', '3', '4',
                    '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
        }
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