1 /*
   2  * Copyright (c) 2000, 2006, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 
  27 package java.util.logging;
  28 
  29 /**
  30  * A Formatter provides support for formatting LogRecords.
  31  * <p>
  32  * Typically each logging Handler will have a Formatter associated
  33  * with it.  The Formatter takes a LogRecord and converts it to
  34  * a string.
  35  * <p>
  36  * Some formatters (such as the XMLFormatter) need to wrap head
  37  * and tail strings around a set of formatted records. The getHeader
  38  * and getTail methods can be used to obtain these strings.
  39  *
  40  * @since 1.4
  41  */
  42 
  43 public abstract class Formatter {
  44 
  45     /**
  46      * Construct a new formatter.
  47      */
  48     protected Formatter() {
  49     }
  50 
  51     /**
  52      * Format the given log record and return the formatted string.
  53      * <p>
  54      * The resulting formatted String will normally include a
  55      * localized and formatted version of the LogRecord's message field.
  56      * It is recommended to use the {@link Formatter#formatMessage}
  57      * convenience method to localize and format the message field.
  58      *
  59      * @param record the log record to be formatted.
  60      * @return the formatted log record
  61      */
  62     public abstract String format(LogRecord record);
  63 
  64 
  65     /**
  66      * Return the header string for a set of formatted records.
  67      * <p>
  68      * This base class returns an empty string, but this may be
  69      * overridden by subclasses.
  70      *
  71      * @param   h  The target handler (can be null)
  72      * @return  header string
  73      */
  74     public String getHead(Handler h) {
  75         return "";
  76     }
  77 
  78     /**
  79      * Return the tail string for a set of formatted records.
  80      * <p>
  81      * This base class returns an empty string, but this may be
  82      * overridden by subclasses.
  83      *
  84      * @param   h  The target handler (can be null)
  85      * @return  tail string
  86      */
  87     public String getTail(Handler h) {
  88         return "";
  89     }
  90 
  91 
  92     /**
  93      * Localize and format the message string from a log record.  This
  94      * method is provided as a convenience for Formatter subclasses to
  95      * use when they are performing formatting.
  96      * <p>
  97      * The message string is first localized to a format string using
  98      * the record's ResourceBundle.  (If there is no ResourceBundle,
  99      * or if the message key is not found, then the key is used as the
 100      * format string.)  The format String uses java.text style
 101      * formatting.
 102      * <ul>
 103      * <li>If there are no parameters, no formatter is used.
 104      * <li>Otherwise, if the string contains "{0" then
 105      *     java.text.MessageFormat  is used to format the string.
 106      * <li>Otherwise no formatting is performed.
 107      * </ul>
 108      * <p>
 109      *
 110      * @param  record  the log record containing the raw message
 111      * @return   a localized and formatted message
 112      */
 113     public synchronized String formatMessage(LogRecord record) {
 114         String format = record.getMessage();
 115         java.util.ResourceBundle catalog = record.getResourceBundle();
 116         if (catalog != null) {
 117             try {
 118                 format = catalog.getString(record.getMessage());
 119             } catch (java.util.MissingResourceException ex) {
 120                 // Drop through.  Use record message as format
 121                 format = record.getMessage();
 122             }
 123         }
 124         // Do the formatting.
 125         try {
 126             Object parameters[] = record.getParameters();
 127             if (parameters == null || parameters.length == 0) {
 128                 // No parameters.  Just return format string.
 129                 return format;
 130             }
 131             // Is it a java.text style format?
 132             // Ideally we could match with
 133             // Pattern.compile("\\{\\d").matcher(format).find())
 134             // However the cost is 14% higher, so we cheaply check for
 135             // 1 of the first 4 parameters
 136             if (format.indexOf("{0") >= 0 || format.indexOf("{1") >=0 ||
 137                         format.indexOf("{2") >=0|| format.indexOf("{3") >=0) {
 138                 return java.text.MessageFormat.format(format, parameters);
 139             }
 140             return format;
 141 
 142         } catch (Exception ex) {
 143             // Formatting failed: use localized format string.
 144             return format;
 145         }
 146     }
 147 }