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.UnsupportedEncodingException; 30 /** 31 * A <tt>Handler</tt> object takes log messages from a <tt>Logger</tt> and 32 * exports them. It might for example, write them to a console 33 * or write them to a file, or send them to a network logging service, 34 * or forward them to an OS log, or whatever. 35 * <p> 36 * A <tt>Handler</tt> can be disabled by doing a <tt>setLevel(Level.OFF)</tt> 37 * and can be re-enabled by doing a <tt>setLevel</tt> with an appropriate level. 38 * <p> 39 * <tt>Handler</tt> classes typically use <tt>LogManager</tt> properties to set 40 * default values for the <tt>Handler</tt>'s <tt>Filter</tt>, <tt>Formatter</tt>, 41 * and <tt>Level</tt>. See the specific documentation for each concrete 42 * <tt>Handler</tt> class. 43 * 44 * 45 * @since 1.4 46 */ 47 48 public abstract class Handler { 49 private static final int offValue = Level.OFF.intValue(); 50 private final LogManager manager = LogManager.getLogManager(); 51 52 // We're using volatile here to avoid synchronizing getters, which 53 // would prevent other threads from calling isLoggable() 54 // while publish() is executing. 55 // On the other hand, setters will be synchronized to exclude concurrent 56 // execution with more complex methods, such as StreamHandler.publish(). 57 // We wouldn't want 'level' to be changed by another thread in the middle 58 // of the execution of a 'publish' call. 59 private volatile Filter filter; 60 private volatile Formatter formatter; 61 private volatile Level logLevel = Level.ALL; 62 private volatile ErrorManager errorManager = new ErrorManager(); 63 private volatile String encoding; 64 65 // Package private support for security checking. When sealed 66 // is true, we access check updates to the class. 67 boolean sealed = true; 68 69 /** 70 * Default constructor. The resulting <tt>Handler</tt> has a log 71 * level of <tt>Level.ALL</tt>, no <tt>Formatter</tt>, and no 72 * <tt>Filter</tt>. A default <tt>ErrorManager</tt> instance is installed 73 * as the <tt>ErrorManager</tt>. 74 */ Handler()75 protected Handler() { 76 } 77 78 /** 79 * Publish a <tt>LogRecord</tt>. 80 * <p> 81 * The logging request was made initially to a <tt>Logger</tt> object, 82 * which initialized the <tt>LogRecord</tt> and forwarded it here. 83 * <p> 84 * The <tt>Handler</tt> is responsible for formatting the message, when and 85 * if necessary. The formatting should include localization. 86 * 87 * @param record description of the log event. A null record is 88 * silently ignored and is not published 89 */ publish(LogRecord record)90 public abstract void publish(LogRecord record); 91 92 /** 93 * Flush any buffered output. 94 */ flush()95 public abstract void flush(); 96 97 /** 98 * Close the <tt>Handler</tt> and free all associated resources. 99 * <p> 100 * The close method will perform a <tt>flush</tt> and then close the 101 * <tt>Handler</tt>. After close has been called this <tt>Handler</tt> 102 * should no longer be used. Method calls may either be silently 103 * ignored or may throw runtime exceptions. 104 * 105 * @exception SecurityException if a security manager exists and if 106 * the caller does not have <tt>LoggingPermission("control")</tt>. 107 */ close()108 public abstract void close() throws SecurityException; 109 110 /** 111 * Set a <tt>Formatter</tt>. This <tt>Formatter</tt> will be used 112 * to format <tt>LogRecords</tt> for this <tt>Handler</tt>. 113 * <p> 114 * Some <tt>Handlers</tt> may not use <tt>Formatters</tt>, in 115 * which case the <tt>Formatter</tt> will be remembered, but not used. 116 * <p> 117 * @param newFormatter the <tt>Formatter</tt> to use (may not be null) 118 * @exception SecurityException if a security manager exists and if 119 * the caller does not have <tt>LoggingPermission("control")</tt>. 120 */ setFormatter(Formatter newFormatter)121 public synchronized void setFormatter(Formatter newFormatter) throws SecurityException { 122 checkPermission(); 123 // Check for a null pointer: 124 newFormatter.getClass(); 125 formatter = newFormatter; 126 } 127 128 /** 129 * Return the <tt>Formatter</tt> for this <tt>Handler</tt>. 130 * @return the <tt>Formatter</tt> (may be null). 131 */ getFormatter()132 public Formatter getFormatter() { 133 return formatter; 134 } 135 136 /** 137 * Set the character encoding used by this <tt>Handler</tt>. 138 * <p> 139 * The encoding should be set before any <tt>LogRecords</tt> are written 140 * to the <tt>Handler</tt>. 141 * 142 * @param encoding The name of a supported character encoding. 143 * May be null, to indicate the default platform encoding. 144 * @exception SecurityException if a security manager exists and if 145 * the caller does not have <tt>LoggingPermission("control")</tt>. 146 * @exception UnsupportedEncodingException if the named encoding is 147 * not supported. 148 */ setEncoding(String encoding)149 public synchronized void setEncoding(String encoding) 150 throws SecurityException, java.io.UnsupportedEncodingException { 151 checkPermission(); 152 if (encoding != null) { 153 try { 154 if(!java.nio.charset.Charset.isSupported(encoding)) { 155 throw new UnsupportedEncodingException(encoding); 156 } 157 } catch (java.nio.charset.IllegalCharsetNameException e) { 158 throw new UnsupportedEncodingException(encoding); 159 } 160 } 161 this.encoding = encoding; 162 } 163 164 /** 165 * Return the character encoding for this <tt>Handler</tt>. 166 * 167 * @return The encoding name. May be null, which indicates the 168 * default encoding should be used. 169 */ getEncoding()170 public String getEncoding() { 171 return encoding; 172 } 173 174 /** 175 * Set a <tt>Filter</tt> to control output on this <tt>Handler</tt>. 176 * <P> 177 * For each call of <tt>publish</tt> the <tt>Handler</tt> will call 178 * this <tt>Filter</tt> (if it is non-null) to check if the 179 * <tt>LogRecord</tt> should be published or discarded. 180 * 181 * @param newFilter a <tt>Filter</tt> object (may be null) 182 * @exception SecurityException if a security manager exists and if 183 * the caller does not have <tt>LoggingPermission("control")</tt>. 184 */ setFilter(Filter newFilter)185 public synchronized void setFilter(Filter newFilter) throws SecurityException { 186 checkPermission(); 187 filter = newFilter; 188 } 189 190 /** 191 * Get the current <tt>Filter</tt> for this <tt>Handler</tt>. 192 * 193 * @return a <tt>Filter</tt> object (may be null) 194 */ getFilter()195 public Filter getFilter() { 196 return filter; 197 } 198 199 /** 200 * Define an ErrorManager for this Handler. 201 * <p> 202 * The ErrorManager's "error" method will be invoked if any 203 * errors occur while using this Handler. 204 * 205 * @param em the new ErrorManager 206 * @exception SecurityException if a security manager exists and if 207 * the caller does not have <tt>LoggingPermission("control")</tt>. 208 */ setErrorManager(ErrorManager em)209 public synchronized void setErrorManager(ErrorManager em) { 210 checkPermission(); 211 if (em == null) { 212 throw new NullPointerException(); 213 } 214 errorManager = em; 215 } 216 217 /** 218 * Retrieves the ErrorManager for this Handler. 219 * 220 * @return the ErrorManager for this Handler 221 * @exception SecurityException if a security manager exists and if 222 * the caller does not have <tt>LoggingPermission("control")</tt>. 223 */ getErrorManager()224 public ErrorManager getErrorManager() { 225 checkPermission(); 226 return errorManager; 227 } 228 229 /** 230 * Protected convenience method to report an error to this Handler's 231 * ErrorManager. Note that this method retrieves and uses the ErrorManager 232 * without doing a security check. It can therefore be used in 233 * environments where the caller may be non-privileged. 234 * 235 * @param msg a descriptive string (may be null) 236 * @param ex an exception (may be null) 237 * @param code an error code defined in ErrorManager 238 */ reportError(String msg, Exception ex, int code)239 protected void reportError(String msg, Exception ex, int code) { 240 try { 241 errorManager.error(msg, ex, code); 242 } catch (Exception ex2) { 243 System.err.println("Handler.reportError caught:"); 244 ex2.printStackTrace(); 245 } 246 } 247 248 /** 249 * Set the log level specifying which message levels will be 250 * logged by this <tt>Handler</tt>. Message levels lower than this 251 * value will be discarded. 252 * <p> 253 * The intention is to allow developers to turn on voluminous 254 * logging, but to limit the messages that are sent to certain 255 * <tt>Handlers</tt>. 256 * 257 * @param newLevel the new value for the log level 258 * @exception SecurityException if a security manager exists and if 259 * the caller does not have <tt>LoggingPermission("control")</tt>. 260 */ setLevel(Level newLevel)261 public synchronized void setLevel(Level newLevel) throws SecurityException { 262 if (newLevel == null) { 263 throw new NullPointerException(); 264 } 265 checkPermission(); 266 logLevel = newLevel; 267 } 268 269 /** 270 * Get the log level specifying which messages will be 271 * logged by this <tt>Handler</tt>. Message levels lower 272 * than this level will be discarded. 273 * @return the level of messages being logged. 274 */ getLevel()275 public Level getLevel() { 276 return logLevel; 277 } 278 279 /** 280 * Check if this <tt>Handler</tt> would actually log a given <tt>LogRecord</tt>. 281 * <p> 282 * This method checks if the <tt>LogRecord</tt> has an appropriate 283 * <tt>Level</tt> and whether it satisfies any <tt>Filter</tt>. It also 284 * may make other <tt>Handler</tt> specific checks that might prevent a 285 * handler from logging the <tt>LogRecord</tt>. It will return false if 286 * the <tt>LogRecord</tt> is null. 287 * <p> 288 * @param record a <tt>LogRecord</tt> 289 * @return true if the <tt>LogRecord</tt> would be logged. 290 * 291 */ isLoggable(LogRecord record)292 public boolean isLoggable(LogRecord record) { 293 final int levelValue = getLevel().intValue(); 294 if (record.getLevel().intValue() < levelValue || levelValue == offValue) { 295 return false; 296 } 297 final Filter filter = getFilter(); 298 if (filter == null) { 299 return true; 300 } 301 return filter.isLoggable(record); 302 } 303 304 // Package-private support method for security checks. 305 // If "sealed" is true, we check that the caller has 306 // appropriate security privileges to update Handler 307 // state and if not throw a SecurityException. checkPermission()308 void checkPermission() throws SecurityException { 309 if (sealed) { 310 manager.checkPermission(); 311 } 312 } 313 } 314