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   * Copyright (c) 2000, 2006, Oracle and/or its affiliates. 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.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  
  package java.util.logging;
  
  /**
   * A Formatter provides support for formatting LogRecords.
   * <p>
   * Typically each logging Handler will have a Formatter associated
   * with it.  The Formatter takes a LogRecord and converts it to
   * a string.
   * <p>
   * Some formatters (such as the XMLFormatter) need to wrap head
   * and tail strings around a set of formatted records. The getHeader
   * and getTail methods can be used to obtain these strings.
   *
   * @since 1.4
   */
  
  public abstract class Formatter {
  
      /**
       * Construct a new formatter.
       */
      protected Formatter() {
      }
  
      /**
       * Format the given log record and return the formatted string.
       * <p>
       * The resulting formatted String will normally include a
       * localized and formatted version of the LogRecord's message field.
       * It is recommended to use the {@link Formatter#formatMessage}
       * convenience method to localize and format the message field.
       *
       * @param record the log record to be formatted.
       * @return the formatted log record
       */
      public abstract String format(LogRecord record);
  
  
      /**
       * Return the header string for a set of formatted records.
       * <p>
       * This base class returns an empty string, but this may be
       * overridden by subclasses.
       *
       * @param   h  The target handler (can be null)
       * @return  header string
       */
      public String getHead(Handler h) {
          return "";
      }
  
      /**
       * Return the tail string for a set of formatted records.
       * <p>
       * This base class returns an empty string, but this may be
       * overridden by subclasses.
       *
       * @param   h  The target handler (can be null)
       * @return  tail string
       */
      public String getTail(Handler h) {
          return "";
      }
  
  
      /**
       * Localize and format the message string from a log record.  This
       * method is provided as a convenience for Formatter subclasses to
       * use when they are performing formatting.
       * <p>
       * The message string is first localized to a format string using
       * the record's ResourceBundle.  (If there is no ResourceBundle,
       * or if the message key is not found, then the key is used as the
       * format string.)  The format String uses java.text style
       * formatting.
       * <ul>
       * <li>If there are no parameters, no formatter is used.
       * <li>Otherwise, if the string contains "{0" then
       *     java.text.MessageFormat  is used to format the string.
       * <li>Otherwise no formatting is performed.
       * </ul>
       * <p>
       *
       * @param  record  the log record containing the raw message
       * @return   a localized and formatted message
       */
      public synchronized String formatMessage(LogRecord record) {
          String format = record.getMessage();
          java.util.ResourceBundle catalog = record.getResourceBundle();
          if (catalog != null) {
              try {
                  format = catalog.getString(record.getMessage());
              } catch (java.util.MissingResourceException ex) {
                  // Drop through.  Use record message as format
                  format = record.getMessage();
              }
          }
          // Do the formatting.
          try {
              Object parameters[] = record.getParameters();
              if (parameters == null || parameters.length == 0) {
                  // No parameters.  Just return format string.
                  return format;
              }
              // Is it a java.text style format?
              // Ideally we could match with
              // Pattern.compile("\\{\\d").matcher(format).find())
              // However the cost is 14% higher, so we cheaply check for
              // 1 of the first 4 parameters
              if (format.indexOf("{0") >= 0 || format.indexOf("{1") >=0 ||
                          format.indexOf("{2") >=0|| format.indexOf("{3") >=0) {
                  return java.text.MessageFormat.format(format, parameters);
              }
              return format;
  
          } catch (Exception ex) {
              // Formatting failed: use localized format string.
              return format;
          }
      }
  }
  