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1: /* Formatter.java -- 2: A class for formatting log messages by localizing message texts 3: and performing substitution of parameters 4: Copyright (C) 2002, 2004 Free Software Foundation, Inc. 5: 6: This file is part of GNU Classpath. 7: 8: GNU Classpath is free software; you can redistribute it and/or modify 9: it under the terms of the GNU General Public License as published by 10: the Free Software Foundation; either version 2, or (at your option) 11: any later version. 12: 13: GNU Classpath is distributed in the hope that it will be useful, but 14: WITHOUT ANY WARRANTY; without even the implied warranty of 15: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 16: General Public License for more details. 17: 18: You should have received a copy of the GNU General Public License 19: along with GNU Classpath; see the file COPYING. If not, write to the 20: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 21: 02110-1301 USA. 22: 23: Linking this library statically or dynamically with other modules is 24: making a combined work based on this library. Thus, the terms and 25: conditions of the GNU General Public License cover the whole 26: combination. 27: 28: As a special exception, the copyright holders of this library give you 29: permission to link this library with independent modules to produce an 30: executable, regardless of the license terms of these independent 31: modules, and to copy and distribute the resulting executable under 32: terms of your choice, provided that you also meet, for each linked 33: independent module, the terms and conditions of the license of that 34: module. An independent module is a module which is not derived from 35: or based on this library. If you modify this library, you may extend 36: this exception to your version of the library, but you are not 37: obligated to do so. If you do not wish to do so, delete this 38: exception statement from your version. */ 39: 40: 41: package java.util.logging; 42: 43: import java.text.MessageFormat; 44: import java.util.ResourceBundle; 45: 46: /** 47: * A <code>Formatter</code> supports handlers by localizing 48: * message texts and by subsituting parameter values for their 49: * placeholders. 50: * 51: * @author Sascha Brawer (brawer@acm.org) 52: */ 53: public abstract class Formatter 54: { 55: /** 56: * Constructs a new Formatter. 57: */ 58: protected Formatter() 59: { 60: } 61: 62: 63: /** 64: * Formats a LogRecord into a string. Usually called by handlers 65: * which need a string for a log record, for example to append 66: * a record to a log file or to transmit a record over the network. 67: * 68: * @param record the log record for which a string form is requested. 69: */ 70: public abstract String format(LogRecord record); 71: 72: 73: /** 74: * Returns a string that handlers are supposed to emit before 75: * the first log record. The base implementation returns an 76: * empty string, but subclasses such as {@link XMLFormatter} 77: * override this method in order to provide a suitable header. 78: * 79: * @return a string for the header. 80: * 81: * @param handler the handler which will prepend the returned 82: * string in front of the first log record. This method 83: * may inspect certain properties of the handler, for 84: * example its encoding, in order to construct the header. 85: */ 86: public String getHead(Handler handler) 87: { 88: return ""; 89: } 90: 91: 92: /** 93: * Returns a string that handlers are supposed to emit after 94: * the last log record. The base implementation returns an 95: * empty string, but subclasses such as {@link XMLFormatter} 96: * override this method in order to provide a suitable tail. 97: * 98: * @return a string for the header. 99: * 100: * @param handler the handler which will append the returned 101: * string after the last log record. This method 102: * may inspect certain properties of the handler 103: * in order to construct the tail. 104: */ 105: public String getTail(Handler handler) 106: { 107: return ""; 108: } 109: 110: 111: /** 112: * Formats the message part of a log record. 113: * 114: * <p>First, the Formatter localizes the record message to the 115: * default locale by looking up the message in the record's 116: * localization resource bundle. If this step fails because there 117: * is no resource bundle associated with the record, or because the 118: * record message is not a key in the bundle, the raw message is 119: * used instead. 120: * 121: * <p>Second, the Formatter substitutes appropriate strings for 122: * the message parameters. If the record returns a non-empty 123: * array for <code>getParameters()</code> and the localized 124: * message string contains the character sequence "{0", the 125: * formatter uses <code>java.text.MessageFormat</code> to format 126: * the message. Otherwise, no parameter substitution is performed. 127: * 128: * @param record the log record to be localized and formatted. 129: * 130: * @return the localized message text where parameters have been 131: * substituted by suitable strings. 132: * 133: * @throws NullPointerException if <code>record</code> 134: * is <code>null</code>. 135: */ 136: public String formatMessage(LogRecord record) 137: { 138: String msg; 139: ResourceBundle bundle; 140: Object[] params; 141: 142: /* This will throw a NullPointerExceptionif record is null. */ 143: msg = record.getMessage(); 144: if (msg == null) 145: msg = ""; 146: 147: /* Try to localize the message. */ 148: bundle = record.getResourceBundle(); 149: if (bundle != null) 150: { 151: try 152: { 153: msg = bundle.getString(msg); 154: } 155: catch (java.util.MissingResourceException _) 156: { 157: } 158: } 159: 160: /* Format the message if there are parameters. */ 161: params = record.getParameters(); 162: if ((params != null) 163: && (params.length > 0) 164: && (msg.indexOf("{0") >= 0)) 165: { 166: msg = MessageFormat.format(msg, params); 167: } 168: 169: return msg; 170: } 171: }