streamhandler.java

gcc的JAVA模块的源代码

       * 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);
    }
  }
}