1 /* 2 * Copyright (c) 2000, 2013, 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 import java.security.AccessController; 31 import java.security.PrivilegedAction; 32 import java.util.Objects; 33 34 /** 35 * Stream based logging <tt>Handler</tt>. 36 * <p> 37 * This is primarily intended as a base class or support class to 38 * be used in implementing other logging <tt>Handlers</tt>. 39 * <p> 40 * <tt>LogRecords</tt> are published to a given <tt>java.io.OutputStream</tt>. 41 * <p> 42 * <b>Configuration:</b> 43 * By default each <tt>StreamHandler</tt> is initialized using the following 44 * <tt>LogManager</tt> configuration properties where <tt><handler-name></tt> 45 * refers to the fully-qualified class name of the handler. 46 * If properties are not defined 47 * (or have invalid values) then the specified default values are used. 48 * <ul> 49 * <li> <handler-name>.level 50 * specifies the default level for the <tt>Handler</tt> 51 * (defaults to <tt>Level.INFO</tt>). </li> 52 * <li> <handler-name>.filter 53 * specifies the name of a <tt>Filter</tt> class to use 54 * (defaults to no <tt>Filter</tt>). </li> 55 * <li> <handler-name>.formatter 56 * specifies the name of a <tt>Formatter</tt> class to use 57 * (defaults to <tt>java.util.logging.SimpleFormatter</tt>). </li> 58 * <li> <handler-name>.encoding 59 * the name of the character set encoding to use (defaults to 60 * the default platform encoding). </li> 61 * </ul> 62 * <p> 63 * For example, the properties for {@code StreamHandler} would be: 64 * <ul> 65 * <li> java.util.logging.StreamHandler.level=INFO </li> 66 * <li> java.util.logging.StreamHandler.formatter=java.util.logging.SimpleFormatter </li> 67 * </ul> 68 * <p> 69 * For a custom handler, e.g. com.foo.MyHandler, the properties would be: 70 * <ul> 71 * <li> com.foo.MyHandler.level=INFO </li> 72 * <li> com.foo.MyHandler.formatter=java.util.logging.SimpleFormatter </li> 73 * </ul> 74 * <p> 75 * @since 1.4 76 */ 77 78 public class StreamHandler extends Handler { 79 private OutputStream output; 80 private boolean doneHeader; 81 private volatile Writer writer; 82 83 /** 84 * Create a <tt>StreamHandler</tt>, with no current output stream. 85 */ 86 public StreamHandler() { 87 // configure with specific defaults for StreamHandler 88 super(Level.INFO, new SimpleFormatter(), null); 89 } 90 91 /** 92 * Create a <tt>StreamHandler</tt> with a given <tt>Formatter</tt> 93 * and output stream. 94 * <p> 95 * @param out the target output stream 96 * @param formatter Formatter to be used to format output 97 */ 98 public StreamHandler(OutputStream out, Formatter formatter) { 99 // configure with default level but use specified formatter 100 super(Level.INFO, null, Objects.requireNonNull(formatter)); 101 102 setOutputStreamPrivileged(out); 103 } 104 105 /** 106 * @see Handler#Handler(Level, Formatter, Formatter) 107 */ 108 StreamHandler(Level defaultLevel, 109 Formatter defaultFormatter, 110 Formatter specifiedFormatter) { 111 super(defaultLevel, defaultFormatter, specifiedFormatter); 112 } 113 114 /** 115 * Change the output stream. 116 * <P> 117 * If there is a current output stream then the <tt>Formatter</tt>'s 118 * tail string is written and the stream is flushed and closed. 119 * Then the output stream is replaced with the new output stream. 120 * 121 * @param out New output stream. May not be null. 122 * @exception SecurityException if a security manager exists and if 123 * the caller does not have <tt>LoggingPermission("control")</tt>. 124 */ 125 protected synchronized void setOutputStream(OutputStream out) throws SecurityException { 126 if (out == null) { 127 throw new NullPointerException(); 128 } 129 flushAndClose(); 130 output = out; 131 doneHeader = false; 132 String encoding = getEncoding(); 133 if (encoding == null) { 134 writer = new OutputStreamWriter(output); 135 } else { 136 try { 137 writer = new OutputStreamWriter(output, encoding); 138 } catch (UnsupportedEncodingException ex) { 139 // This shouldn't happen. The setEncoding method 140 // should have validated that the encoding is OK. 141 throw new Error("Unexpected exception " + ex); 142 } 143 } 144 } 145 146 /** 147 * Set (or change) the character encoding used by this <tt>Handler</tt>. 148 * <p> 149 * The encoding should be set before any <tt>LogRecords</tt> are written 150 * to the <tt>Handler</tt>. 151 * 152 * @param encoding The name of a supported character encoding. 153 * May be null, to indicate the default platform encoding. 154 * @exception SecurityException if a security manager exists and if 155 * the caller does not have <tt>LoggingPermission("control")</tt>. 156 * @exception UnsupportedEncodingException if the named encoding is 157 * not supported. 158 */ 159 @Override 160 public synchronized void setEncoding(String encoding) 161 throws SecurityException, java.io.UnsupportedEncodingException { 162 super.setEncoding(encoding); 163 if (output == null) { 164 return; 165 } 166 // Replace the current writer with a writer for the new encoding. 167 flush(); 168 if (encoding == null) { 169 writer = new OutputStreamWriter(output); 170 } else { 171 writer = new OutputStreamWriter(output, encoding); 172 } 173 } 174 175 /** 176 * Format and publish a <tt>LogRecord</tt>. 177 * <p> 178 * The <tt>StreamHandler</tt> first checks if there is an <tt>OutputStream</tt> 179 * and if the given <tt>LogRecord</tt> has at least the required log level. 180 * If not it silently returns. If so, it calls any associated 181 * <tt>Filter</tt> to check if the record should be published. If so, 182 * it calls its <tt>Formatter</tt> to format the record and then writes 183 * the result to the current output stream. 184 * <p> 185 * If this is the first <tt>LogRecord</tt> to be written to a given 186 * <tt>OutputStream</tt>, the <tt>Formatter</tt>'s "head" string is 187 * written to the stream before the <tt>LogRecord</tt> is written. 188 * 189 * @param record description of the log event. A null record is 190 * silently ignored and is not published 191 */ 192 @Override 193 public synchronized void publish(LogRecord record) { 194 if (!isLoggable(record)) { 195 return; 196 } 197 String msg; 198 try { 199 msg = getFormatter().format(record); 200 } catch (Exception ex) { 201 // We don't want to throw an exception here, but we 202 // report the exception to any registered ErrorManager. 203 reportError(null, ex, ErrorManager.FORMAT_FAILURE); 204 return; 205 } 206 207 try { 208 if (!doneHeader) { 209 writer.write(getFormatter().getHead(this)); 210 doneHeader = true; 211 } 212 writer.write(msg); 213 } catch (Exception ex) { 214 // We don't want to throw an exception here, but we 215 // report the exception to any registered ErrorManager. 216 reportError(null, ex, ErrorManager.WRITE_FAILURE); 217 } 218 } 219 220 221 /** 222 * Check if this <tt>Handler</tt> would actually log a given <tt>LogRecord</tt>. 223 * <p> 224 * This method checks if the <tt>LogRecord</tt> has an appropriate level and 225 * whether it satisfies any <tt>Filter</tt>. It will also return false if 226 * no output stream has been assigned yet or the LogRecord is null. 227 * <p> 228 * @param record a <tt>LogRecord</tt> 229 * @return true if the <tt>LogRecord</tt> would be logged. 230 * 231 */ 232 @Override 233 public boolean isLoggable(LogRecord record) { 234 if (writer == null || record == null) { 235 return false; 236 } 237 return super.isLoggable(record); 238 } 239 240 /** 241 * Flush any buffered messages. 242 */ 243 @Override 244 public synchronized void flush() { 245 if (writer != null) { 246 try { 247 writer.flush(); 248 } catch (Exception ex) { 249 // We don't want to throw an exception here, but we 250 // report the exception to any registered ErrorManager. 251 reportError(null, ex, ErrorManager.FLUSH_FAILURE); 252 } 253 } 254 } 255 256 private synchronized void flushAndClose() throws SecurityException { 257 checkPermission(); 258 if (writer != null) { 259 try { 260 if (!doneHeader) { 261 writer.write(getFormatter().getHead(this)); 262 doneHeader = true; 263 } 264 writer.write(getFormatter().getTail(this)); 265 writer.flush(); 266 writer.close(); 267 } catch (Exception ex) { 268 // We don't want to throw an exception here, but we 269 // report the exception to any registered ErrorManager. 270 reportError(null, ex, ErrorManager.CLOSE_FAILURE); 271 } 272 writer = null; 273 output = null; 274 } 275 } 276 277 /** 278 * Close the current output stream. 279 * <p> 280 * The <tt>Formatter</tt>'s "tail" string is written to the stream before it 281 * is closed. In addition, if the <tt>Formatter</tt>'s "head" string has not 282 * yet been written to the stream, it will be written before the 283 * "tail" string. 284 * 285 * @exception SecurityException if a security manager exists and if 286 * the caller does not have LoggingPermission("control"). 287 */ 288 @Override 289 public synchronized void close() throws SecurityException { 290 flushAndClose(); 291 } 292 293 // Package-private support for setting OutputStream 294 // with elevated privilege. 295 final void setOutputStreamPrivileged(final OutputStream out) { 296 AccessController.doPrivileged(new PrivilegedAction<Void>() { 297 @Override 298 public Void run() { 299 setOutputStream(out); 300 return null; 301 } 302 }, null, LogManager.controlPermission); 303 } 304 }