1 /* 2 * Copyright (c) 2000, 2012, 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 import java.io.*; 30 31 /** 32 * Stream based logging <tt>Handler</tt>. 33 * <p> 34 * This is primarily intended as a base class or support class to 35 * be used in implementing other logging <tt>Handlers</tt>. 36 * <p> 37 * <tt>LogRecords</tt> are published to a given <tt>java.io.OutputStream</tt>. 38 * <p> 39 * <b>Configuration:</b> 40 * By default each <tt>StreamHandler</tt> is initialized using the following 41 * <tt>LogManager</tt> configuration properties where <tt><handler-name></tt> 42 * refers to the fully-qualified class name of the handler. 43 * If properties are not defined 44 * (or have invalid values) then the specified default values are used. 45 * <ul> 46 * <li> <handler-name>.level 47 * specifies the default level for the <tt>Handler</tt> 48 * (defaults to <tt>Level.INFO</tt>). </li> 49 * <li> <handler-name>.filter 50 * specifies the name of a <tt>Filter</tt> class to use 51 * (defaults to no <tt>Filter</tt>). </li> 52 * <li> <handler-name>.formatter 53 * specifies the name of a <tt>Formatter</tt> class to use 54 * (defaults to <tt>java.util.logging.SimpleFormatter</tt>). </li> 55 * <li> <handler-name>.encoding 56 * the name of the character set encoding to use (defaults to 57 * the default platform encoding). </li> 58 * </ul> 59 * <p> 60 * For example, the properties for {@code StreamHandler} would be: 61 * <ul> 62 * <li> java.util.logging.StreamHandler.level=INFO </li> 63 * <li> java.util.logging.StreamHandler.formatter=java.util.logging.SimpleFormatter </li> 64 * </ul> 65 * <p> 66 * For a custom handler, e.g. com.foo.MyHandler, the properties would be: 67 * <ul> 68 * <li> com.foo.MyHandler.level=INFO </li> 69 * <li> com.foo.MyHandler.formatter=java.util.logging.SimpleFormatter </li> 70 * </ul> 71 * <p> 72 * @since 1.4 73 */ 74 75 public class StreamHandler extends Handler { 76 private OutputStream output; 77 private boolean doneHeader; 78 private volatile Writer writer; 79 80 // Private method to configure a StreamHandler from LogManager 81 // properties and/or default values as specified in the class 82 // javadoc. 83 private void configure() { 84 LogManager manager = LogManager.getLogManager(); 85 String cname = getClass().getName(); 86 87 setLevel(manager.getLevelProperty(cname +".level", Level.INFO)); 88 setFilter(manager.getFilterProperty(cname +".filter", null)); 89 setFormatter(manager.getFormatterProperty(cname +".formatter", new SimpleFormatter())); 90 try { 91 setEncoding(manager.getStringProperty(cname +".encoding", null)); 92 } catch (Exception ex) { 93 try { 94 setEncoding(null); 95 } catch (Exception ex2) { 96 // doing a setEncoding with null should always work. 97 // assert false; 98 } 99 } 100 } 101 102 /** 103 * Create a <tt>StreamHandler</tt>, with no current output stream. 104 */ 105 public StreamHandler() { 106 doWithControlPermission(this::configure); 107 } 108 109 /** 110 * Create a <tt>StreamHandler</tt> with a given <tt>Formatter</tt> 111 * and output stream. 112 * <p> 113 * @param out the target output stream 114 * @param formatter Formatter to be used to format output 115 */ 116 public StreamHandler(OutputStream out, Formatter formatter) { 117 doWithControlPermission(() -> { 118 configure(); 119 setFormatter(formatter); 120 setOutputStream(out); 121 }); 122 } 123 124 /** 125 * Change the output stream. 126 * <P> 127 * If there is a current output stream then the <tt>Formatter</tt>'s 128 * tail string is written and the stream is flushed and closed. 129 * Then the output stream is replaced with the new output stream. 130 * 131 * @param out New output stream. May not be null. 132 * @exception SecurityException if a security manager exists and if 133 * the caller does not have <tt>LoggingPermission("control")</tt>. 134 */ 135 protected synchronized void setOutputStream(OutputStream out) throws SecurityException { 136 if (out == null) { 137 throw new NullPointerException(); 138 } 139 flushAndClose(); 140 output = out; 141 doneHeader = false; 142 String encoding = getEncoding(); 143 if (encoding == null) { 144 writer = new OutputStreamWriter(output); 145 } else { 146 try { 147 writer = new OutputStreamWriter(output, encoding); 148 } catch (UnsupportedEncodingException ex) { 149 // This shouldn't happen. The setEncoding method 150 // should have validated that the encoding is OK. 151 throw new Error("Unexpected exception " + ex); 152 } 153 } 154 } 155 156 /** 157 * Set (or change) the character encoding used by this <tt>Handler</tt>. 158 * <p> 159 * The encoding should be set before any <tt>LogRecords</tt> are written 160 * to the <tt>Handler</tt>. 161 * 162 * @param encoding The name of a supported character encoding. 163 * May be null, to indicate the default platform encoding. 164 * @exception SecurityException if a security manager exists and if 165 * the caller does not have <tt>LoggingPermission("control")</tt>. 166 * @exception UnsupportedEncodingException if the named encoding is 167 * not supported. 168 */ 169 @Override 170 public synchronized void setEncoding(String encoding) 171 throws SecurityException, java.io.UnsupportedEncodingException { 172 super.setEncoding(encoding); 173 if (output == null) { 174 return; 175 } 176 // Replace the current writer with a writer for the new encoding. 177 flush(); 178 if (encoding == null) { 179 writer = new OutputStreamWriter(output); 180 } else { 181 writer = new OutputStreamWriter(output, encoding); 182 } 183 } 184 185 /** 186 * Format and publish a <tt>LogRecord</tt>. 187 * <p> 188 * The <tt>StreamHandler</tt> first checks if there is an <tt>OutputStream</tt> 189 * and if the given <tt>LogRecord</tt> has at least the required log level. 190 * If not it silently returns. If so, it calls any associated 191 * <tt>Filter</tt> to check if the record should be published. If so, 192 * it calls its <tt>Formatter</tt> to format the record and then writes 193 * the result to the current output stream. 194 * <p> 195 * If this is the first <tt>LogRecord</tt> to be written to a given 196 * <tt>OutputStream</tt>, the <tt>Formatter</tt>'s "head" string is 197 * written to the stream before the <tt>LogRecord</tt> is written. 198 * 199 * @param record description of the log event. A null record is 200 * silently ignored and is not published 201 */ 202 @Override 203 public synchronized void publish(LogRecord record) { 204 if (!isLoggable(record)) { 205 return; 206 } 207 String msg; 208 try { 209 msg = getFormatter().format(record); 210 } catch (Exception ex) { 211 // We don't want to throw an exception here, but we 212 // report the exception to any registered ErrorManager. 213 reportError(null, ex, ErrorManager.FORMAT_FAILURE); 214 return; 215 } 216 217 try { 218 if (!doneHeader) { 219 writer.write(getFormatter().getHead(this)); 220 doneHeader = true; 221 } 222 writer.write(msg); 223 } catch (Exception ex) { 224 // We don't want to throw an exception here, but we 225 // report the exception to any registered ErrorManager. 226 reportError(null, ex, ErrorManager.WRITE_FAILURE); 227 } 228 } 229 230 231 /** 232 * Check if this <tt>Handler</tt> would actually log a given <tt>LogRecord</tt>. 233 * <p> 234 * This method checks if the <tt>LogRecord</tt> has an appropriate level and 235 * whether it satisfies any <tt>Filter</tt>. It will also return false if 236 * no output stream has been assigned yet or the LogRecord is null. 237 * <p> 238 * @param record a <tt>LogRecord</tt> 239 * @return true if the <tt>LogRecord</tt> would be logged. 240 * 241 */ 242 @Override 243 public boolean isLoggable(LogRecord record) { 244 if (writer == null || record == null) { 245 return false; 246 } 247 return super.isLoggable(record); 248 } 249 250 /** 251 * Flush any buffered messages. 252 */ 253 @Override 254 public synchronized void flush() { 255 if (writer != null) { 256 try { 257 writer.flush(); 258 } catch (Exception ex) { 259 // We don't want to throw an exception here, but we 260 // report the exception to any registered ErrorManager. 261 reportError(null, ex, ErrorManager.FLUSH_FAILURE); 262 } 263 } 264 } 265 266 private synchronized void flushAndClose() throws SecurityException { 267 checkPermission(); 268 if (writer != null) { 269 try { 270 if (!doneHeader) { 271 writer.write(getFormatter().getHead(this)); 272 doneHeader = true; 273 } 274 writer.write(getFormatter().getTail(this)); 275 writer.flush(); 276 writer.close(); 277 } catch (Exception ex) { 278 // We don't want to throw an exception here, but we 279 // report the exception to any registered ErrorManager. 280 reportError(null, ex, ErrorManager.CLOSE_FAILURE); 281 } 282 writer = null; 283 output = null; 284 } 285 } 286 287 /** 288 * Close the current output stream. 289 * <p> 290 * The <tt>Formatter</tt>'s "tail" string is written to the stream before it 291 * is closed. In addition, if the <tt>Formatter</tt>'s "head" string has not 292 * yet been written to the stream, it will be written before the 293 * "tail" string. 294 * 295 * @exception SecurityException if a security manager exists and if 296 * the caller does not have LoggingPermission("control"). 297 */ 298 @Override 299 public synchronized void close() throws SecurityException { 300 flushAndClose(); 301 } 302 }