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Diffstat (limited to 'libjava/classpath/java/util/logging/StreamHandler.java')
| -rw-r--r-- | libjava/classpath/java/util/logging/StreamHandler.java | 521 |
1 files changed, 521 insertions, 0 deletions
diff --git a/libjava/classpath/java/util/logging/StreamHandler.java b/libjava/classpath/java/util/logging/StreamHandler.java new file mode 100644 index 00000000000..5c35c1e481d --- /dev/null +++ b/libjava/classpath/java/util/logging/StreamHandler.java @@ -0,0 +1,521 @@ +/* StreamHandler.java -- + A class for publishing log messages to instances of java.io.OutputStream + Copyright (C) 2002 Free Software Foundation, Inc. + +This file is part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2, or (at your option) +any later version. + +GNU Classpath is distributed in the hope that it will be useful, but +WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +General Public License for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; see the file COPYING. If not, write to the +Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301 USA. + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + + +package java.util.logging; + +import java.io.OutputStream; +import java.io.OutputStreamWriter; +import java.io.UnsupportedEncodingException; +import java.io.Writer; + +/** + * A <code>StreamHandler</code> publishes <code>LogRecords</code> to + * a instances of <code>java.io.OutputStream</code>. + * + * @author Sascha Brawer (brawer@acm.org) + */ +public class StreamHandler + extends Handler +{ + private OutputStream out; + private Writer writer; + + + /** + * Indicates the current state of this StreamHandler. The value + * should be one of STATE_FRESH, STATE_PUBLISHED, or STATE_CLOSED. + */ + private int streamState = STATE_FRESH; + + + /** + * streamState having this value indicates that the StreamHandler + * has been created, but the publish(LogRecord) method has not been + * called yet. If the StreamHandler has been constructed without an + * OutputStream, writer will be null, otherwise it is set to a + * freshly created OutputStreamWriter. + */ + private static final int STATE_FRESH = 0; + + + /** + * streamState having this value indicates that the publish(LocRecord) + * method has been called at least once. + */ + private static final int STATE_PUBLISHED = 1; + + + /** + * streamState having this value indicates that the close() method + * has been called. + */ + private static final int STATE_CLOSED = 2; + + + /** + * Creates a <code>StreamHandler</code> without an output stream. + * Subclasses can later use {@link + * #setOutputStream(java.io.OutputStream)} to associate an output + * stream with this StreamHandler. + */ + public StreamHandler() + { + this(null, null); + } + + + /** + * Creates a <code>StreamHandler</code> that formats log messages + * with the specified Formatter and publishes them to the specified + * output stream. + * + * @param out the output stream to which the formatted log messages + * are published. + * + * @param formatter the <code>Formatter</code> that will be used + * to format log messages. + */ + public StreamHandler(OutputStream out, Formatter formatter) + { + this(out, "java.util.logging.StreamHandler", Level.INFO, + formatter, SimpleFormatter.class); + } + + + StreamHandler( + OutputStream out, + String propertyPrefix, + Level defaultLevel, + Formatter formatter, Class defaultFormatterClass) + { + this.level = LogManager.getLevelProperty(propertyPrefix + ".level", + defaultLevel); + + this.filter = (Filter) LogManager.getInstanceProperty( + propertyPrefix + ".filter", + /* must be instance of */ Filter.class, + /* default: new instance of */ null); + + if (formatter != null) + this.formatter = formatter; + else + this.formatter = (Formatter) LogManager.getInstanceProperty( + propertyPrefix + ".formatter", + /* must be instance of */ Formatter.class, + /* default: new instance of */ defaultFormatterClass); + + try + { + String enc = LogManager.getLogManager().getProperty(propertyPrefix + + ".encoding"); + + /* make sure enc actually is a valid encoding */ + if ((enc != null) && (enc.length() > 0)) + new String(new byte[0], enc); + + this.encoding = enc; + } + catch (Exception _) + { + } + + if (out != null) + { + try + { + changeWriter(out, getEncoding()); + } + catch (UnsupportedEncodingException uex) + { + /* This should never happen, since the validity of the encoding + * name has been checked above. + */ + throw new RuntimeException(uex.getMessage()); + } + } + } + + + private void checkOpen() + { + if (streamState == STATE_CLOSED) + throw new IllegalStateException(this.toString() + " has been closed"); + } + + private void checkFresh() + { + checkOpen(); + if (streamState != STATE_FRESH) + throw new IllegalStateException("some log records have been published to " + this); + } + + + private void changeWriter(OutputStream out, String encoding) + throws UnsupportedEncodingException + { + OutputStreamWriter writer; + + /* The logging API says that a null encoding means the default + * platform encoding. However, java.io.OutputStreamWriter needs + * another constructor for the default platform encoding, + * passing null would throw an exception. + */ + if (encoding == null) + writer = new OutputStreamWriter(out); + else + writer = new OutputStreamWriter(out, encoding); + + /* Closing the stream has side effects -- do this only after + * creating a new writer has been successful. + */ + if ((streamState != STATE_FRESH) || (this.writer != null)) + close(); + + this.writer = writer; + this.out = out; + this.encoding = encoding; + streamState = STATE_FRESH; + } + + + /** + * Sets the character encoding which this handler uses for publishing + * log records. The encoding of a <code>StreamHandler</code> must be + * set before any log records have been published. + * + * @param encoding the name of a character encoding, or <code>null</code> + * for the default encoding. + * + * @throws SecurityException if a security manager exists and + * the caller is not granted the permission to control the + * the logging infrastructure. + * + * @exception IllegalStateException if any log records have been + * published to this <code>StreamHandler</code> before. Please + * be aware that this is a pecularity of the GNU implementation. + * While the API specification indicates that it is an error + * if the encoding is set after records have been published, + * it does not mandate any specific behavior for that case. + */ + public void setEncoding(String encoding) + throws SecurityException, UnsupportedEncodingException + { + /* The inherited implementation first checks whether the invoking + * code indeed has the permission to control the logging infra- + * structure, and throws a SecurityException if this was not the + * case. + * + * Next, it verifies that the encoding is supported and throws + * an UnsupportedEncodingExcpetion otherwise. Finally, it remembers + * the name of the encoding. + */ + super.setEncoding(encoding); + + checkFresh(); + + /* If out is null, setEncoding is being called before an output + * stream has been set. In that case, we need to check that the + * encoding is valid, and remember it if this is the case. Since + * this is exactly what the inherited implementation of + * Handler.setEncoding does, we can delegate. + */ + if (out != null) + { + /* The logging API says that a null encoding means the default + * platform encoding. However, java.io.OutputStreamWriter needs + * another constructor for the default platform encoding, passing + * null would throw an exception. + */ + if (encoding == null) + writer = new OutputStreamWriter(out); + else + writer = new OutputStreamWriter(out, encoding); + } + } + + + /** + * Changes the output stream to which this handler publishes + * logging records. + * + * @throws SecurityException if a security manager exists and + * the caller is not granted the permission to control + * the logging infrastructure. + * + * @throws NullPointerException if <code>out</code> + * is <code>null</code>. + */ + protected void setOutputStream(OutputStream out) + throws SecurityException + { + LogManager.getLogManager().checkAccess(); + + /* Throw a NullPointerException if out is null. */ + out.getClass(); + + try + { + changeWriter(out, getEncoding()); + } + catch (UnsupportedEncodingException ex) + { + /* This seems quite unlikely to happen, unless the underlying + * implementation of java.io.OutputStreamWriter changes its + * mind (at runtime) about the set of supported character + * encodings. + */ + throw new RuntimeException(ex.getMessage()); + } + } + + + /** + * Publishes a <code>LogRecord</code> to the associated output + * stream, provided the record passes all tests for being loggable. + * The <code>StreamHandler</code> will localize the message of the + * log record and substitute any message parameters. + * + * <p>Most applications do not need to call this method directly. + * Instead, they will use use a {@link Logger}, which will create + * LogRecords and distribute them to registered handlers. + * + * <p>In case of an I/O failure, the <code>ErrorManager</code> + * of this <code>Handler</code> will be informed, but the caller + * of this method will not receive an exception. + * + * <p>If a log record is being published to a + * <code>StreamHandler</code> that has been closed earlier, the Sun + * J2SE 1.4 reference can be observed to silently ignore the + * call. The GNU implementation, however, intentionally behaves + * differently by informing the <code>ErrorManager</code> associated + * with this <code>StreamHandler</code>. Since the condition + * indicates a programming error, the programmer should be + * informed. It also seems extremely unlikely that any application + * would depend on the exact behavior in this rather obscure, + * erroneous case -- especially since the API specification does not + * prescribe what is supposed to happen. + * + * @param record the log event to be published. + */ + public void publish(LogRecord record) + { + String formattedMessage; + + if (!isLoggable(record)) + return; + + if (streamState == STATE_FRESH) + { + try + { + writer.write(formatter.getHead(this)); + } + catch (java.io.IOException ex) + { + reportError(null, ex, ErrorManager.WRITE_FAILURE); + return; + } + catch (Exception ex) + { + reportError(null, ex, ErrorManager.GENERIC_FAILURE); + return; + } + + streamState = STATE_PUBLISHED; + } + + try + { + formattedMessage = formatter.format(record); + } + catch (Exception ex) + { + reportError(null, ex, ErrorManager.FORMAT_FAILURE); + return; + } + + try + { + writer.write(formattedMessage); + } + catch (Exception ex) + { + reportError(null, ex, ErrorManager.WRITE_FAILURE); + } + } + + + /** + * Checks whether or not a <code>LogRecord</code> would be logged + * if it was passed to this <code>StreamHandler</code> for publication. + * + * <p>The <code>StreamHandler</code> implementation first checks + * whether a writer is present and the handler's level is greater + * than or equal to the severity level threshold. In a second step, + * if a {@link Filter} has been installed, its {@link + * Filter#isLoggable(LogRecord) isLoggable} method is + * invoked. Subclasses of <code>StreamHandler</code> can override + * this method to impose their own constraints. + * + * @param record the <code>LogRecord</code> to be checked. + * + * @return <code>true</code> if <code>record</code> would + * be published by {@link #publish(LogRecord) publish}, + * <code>false</code> if it would be discarded. + * + * @see #setLevel(Level) + * @see #setFilter(Filter) + * @see Filter#isLoggable(LogRecord) + * + * @throws NullPointerException if <code>record</code> is + * <code>null</code>. */ + public boolean isLoggable(LogRecord record) + { + return (writer != null) && super.isLoggable(record); + } + + + /** + * Forces any data that may have been buffered to the underlying + * output device. + * + * <p>In case of an I/O failure, the <code>ErrorManager</code> + * of this <code>Handler</code> will be informed, but the caller + * of this method will not receive an exception. + * + * <p>If a <code>StreamHandler</code> that has been closed earlier + * is closed a second time, the Sun J2SE 1.4 reference can be + * observed to silently ignore the call. The GNU implementation, + * however, intentionally behaves differently by informing the + * <code>ErrorManager</code> associated with this + * <code>StreamHandler</code>. Since the condition indicates a + * programming error, the programmer should be informed. It also + * seems extremely unlikely that any application would depend on the + * exact behavior in this rather obscure, erroneous case -- + * especially since the API specification does not prescribe what is + * supposed to happen. + */ + public void flush() + { + try + { + checkOpen(); + if (writer != null) + writer.flush(); + } + catch (Exception ex) + { + reportError(null, ex, ErrorManager.FLUSH_FAILURE); + } + } + + + /** + * Closes this <code>StreamHandler</code> after having forced any + * data that may have been buffered to the underlying output + * device. + * + * <p>As soon as <code>close</code> has been called, + * a <code>Handler</code> should not be used anymore. Attempts + * to publish log records, to flush buffers, or to modify the + * <code>Handler</code> in any other way may throw runtime + * exceptions after calling <code>close</code>.</p> + * + * <p>In case of an I/O failure, the <code>ErrorManager</code> + * of this <code>Handler</code> will be informed, but the caller + * of this method will not receive an exception.</p> + * + * <p>If a <code>StreamHandler</code> that has been closed earlier + * is closed a second time, the Sun J2SE 1.4 reference can be + * observed to silently ignore the call. The GNU implementation, + * however, intentionally behaves differently by informing the + * <code>ErrorManager</code> associated with this + * <code>StreamHandler</code>. Since the condition indicates a + * programming error, the programmer should be informed. It also + * seems extremely unlikely that any application would depend on the + * exact behavior in this rather obscure, erroneous case -- + * especially since the API specification does not prescribe what is + * supposed to happen. + * + * @throws SecurityException if a security manager exists and + * the caller is not granted the permission to control + * the logging infrastructure. + */ + public void close() + throws SecurityException + { + LogManager.getLogManager().checkAccess(); + + try + { + /* Although flush also calls checkOpen, it catches + * any exceptions and reports them to the ErrorManager + * as flush failures. However, we want to report + * a closed stream as a close failure, not as a + * flush failure here. Therefore, we call checkOpen() + * before flush(). + */ + checkOpen(); + flush(); + + if (writer != null) + { + if (formatter != null) + { + /* Even if the StreamHandler has never published a record, + * it emits head and tail upon closing. An earlier version + * of the GNU Classpath implementation did not emitted + * anything. However, this had caused XML log files to be + * entirely empty instead of containing no log records. + */ + if (streamState == STATE_FRESH) + writer.write(formatter.getHead(this)); + if (streamState != STATE_CLOSED) + writer.write(formatter.getTail(this)); + } + streamState = STATE_CLOSED; + writer.close(); + } + } + catch (Exception ex) + { + reportError(null, ex, ErrorManager.CLOSE_FAILURE); + } + } +} |
