filehandler.java

linux下编程用 编译软件

   *        handler switches to the next file in the rotating set.  A
   *        value of zero means that files can grow without limit.
   *
   * @param count specifies the number of log files through which this
   *        handler cycles.
   *
   * @param append specifies whether the handler will append log
   *        records to existing files (<code>true</code>), or whether the
   *        handler will clear log files upon switching to them
   *        (<code>false</code>).
   *
   * @throws java.io.IOException FIXME: The Sun Javadoc says: "if
   *         there are IO problems opening the files."  This conflicts
   *         with the general principle that configuration errors do
   *         not prohibit construction. Needs review.
   *
   * @throws SecurityException if a security manager exists and
   *         the caller is not granted the permission to control
   *         the logging infrastructure.
   *         <p>FIXME: This seems in contrast to all other handler
   *         constructors -- verify this by running tests against
   *         the Sun reference implementation.
   */
  public FileHandler(String pattern,
		     int limit,
		     int count,
		     boolean append)
    throws IOException, SecurityException
  {
    super(/* output stream, created below */ null,
	  "java.util.logging.FileHandler",
	  /* default level */ Level.ALL,
	  /* formatter */ null,
	  /* default formatter */ XMLFormatter.class);

    if ((limit <0) || (count < 1))
      throw new IllegalArgumentException();

    this.pattern = pattern;
    this.limit = limit;
    this.count = count;
    this.append = append;
    this.written = 0;
    this.logFiles = new LinkedList ();

    setOutputStream (createFileStream (pattern, limit, count, append,
                                       /* generation */ 0));
  }


  /* FIXME: Javadoc missing. */
  private OutputStream createFileStream(String pattern,
                                        int limit,
                                        int count,
                                        boolean append,
                                        int generation)
  {
    String  path;
    int     unique = 0;

    /* Throws a SecurityException if the caller does not have
     * LoggingPermission("control").
     */
    LogManager.getLogManager().checkAccess();

    /* Default value from the java.util.logging.FileHandler.pattern
     * LogManager configuration property.
     */
    if (pattern == null)
      pattern = LogManager.getLogManager().getProperty(
                              "java.util.logging.FileHandler.pattern");
    if (pattern == null)
      pattern = "%h/java%u.log";

    if (count > 1 && !has (pattern, 'g'))
      pattern = pattern + ".%g";

    do
    {
      path = replaceFileNameEscapes(pattern, generation, unique, count);

      try
      {
	File file = new File(path);
        if (!file.exists () || append)
          {
            FileOutputStream fout = new FileOutputStream (file, append);
            // FIXME we need file locks for this to work properly, but they
            // are not implemented yet in Classpath! Madness!
//             FileChannel channel = fout.getChannel ();
//             FileLock lock = channel.tryLock ();
//             if (lock != null) // We've locked the file.
//               {
                if (logFiles.isEmpty ())
                  logFiles.addFirst (path);
                return new ostr (fout);
//               }
          }
      }
      catch (Exception ex)
      {
        reportError (null, ex, ErrorManager.OPEN_FAILURE);
      }

      unique = unique + 1;
      if (!has (pattern, 'u'))
        pattern = pattern + ".%u";
    }
    while (true);
  }


  /**
   * Replaces the substrings <code>"/"</code> by the value of the
   * system property <code>"file.separator"</code>, <code>"%t"</code>
   * by the value of the system property
   * <code>"java.io.tmpdir"</code>, <code>"%h"</code> by the value of
   * the system property <code>"user.home"</code>, <code>"%g"</code>
   * by the value of <code>generation</code>, <code>"%u"</code> by the
   * value of <code>uniqueNumber</code>, and <code>"%%"</code> by a
   * single percent character.  If <code>pattern</code> does
   * <em>not</em> contain the sequence <code>"%g"</code>,
   * the value of <code>generation</code> will be appended to
   * the result.
   *
   * @throws NullPointerException if one of the system properties
   *         <code>"file.separator"</code>,
   *         <code>"java.io.tmpdir"</code>, or
   *         <code>"user.home"</code> has no value and the
   *         corresponding escape sequence appears in
   *         <code>pattern</code>.
   */
  private static String replaceFileNameEscapes(String pattern,
					       int generation,
					       int uniqueNumber,
					       int count)
  {
    StringBuffer buf = new StringBuffer(pattern);
    String       replaceWith;
    boolean      foundGeneration = false;

    int pos = 0;
    do
    {
      // Uncomment the next line for finding bugs.
      // System.out.println(buf.substring(0,pos) + '|' + buf.substring(pos));
      
      if (buf.charAt(pos) == '/')
      {
	/* The same value is also provided by java.io.File.separator. */
	replaceWith = System.getProperty("file.separator");
	buf.replace(pos, pos + 1, replaceWith);
	pos = pos + replaceWith.length() - 1;
	continue;
      }

      if (buf.charAt(pos) == '%')
      {
        switch (buf.charAt(pos + 1))
	{
	case 't':
	  replaceWith = System.getProperty("java.io.tmpdir");
	  break;

	case 'h':
	  replaceWith = System.getProperty("user.home");
	  break;

	case 'g':
	  replaceWith = Integer.toString(generation);
	  foundGeneration = true;
	  break;

	case 'u':
	  replaceWith = Integer.toString(uniqueNumber);
	  break;

	case '%':
	  replaceWith = "%";
	  break;

	default:
	  replaceWith = "??";
	  break; // FIXME: Throw exception?
	}

	buf.replace(pos, pos + 2, replaceWith);
	pos = pos + replaceWith.length() - 1;
	continue;
      }
    }
    while (++pos < buf.length() - 1);

    if (!foundGeneration && (count > 1))
    {
      buf.append('.');
      buf.append(generation);
    }

    return buf.toString();
  }


  /* FIXME: Javadoc missing. */
  public void publish(LogRecord record)
  {
    if (limit > 0 && written >= limit)
      rotate ();
    super.publish(record);
    flush ();
  }

  /**
   * Rotates the current log files, possibly removing one if we
   * exceed the file count.
   */
  private synchronized void rotate ()
  {
    if (logFiles.size () > 0)
      {
        File f1 = null;
        ListIterator lit = null;

        // If we reach the file count, ditch the oldest file.
        if (logFiles.size () == count)
          {
            f1 = new File ((String) logFiles.getLast ());
            f1.delete ();
            lit = logFiles.listIterator (logFiles.size () - 1);
          }
        // Otherwise, move the oldest to a new location.
        else
          {
            String path = replaceFileNameEscapes (pattern, logFiles.size (),
                                                  /* unique */ 0, count);
            f1 = new File (path);
            logFiles.addLast (path);
            lit = logFiles.listIterator (logFiles.size () - 1);
          }

        // Now rotate the files.
        while (lit.hasPrevious ())
          {
            String s = (String) lit.previous ();
            File f2 = new File (s);
            f2.renameTo (f1);
            f1 = f2;
          }
      }

    setOutputStream (createFileStream (pattern, limit, count, append,
                                       /* generation */ 0));

    // Reset written count.
    written = 0;
  }

  /**
   * Tell if <code>pattern</code> contains the pattern sequence
   * with character <code>escape</code>. That is, if <code>escape</code>
   * is 'g', this method returns true if the given pattern contains
   * "%g", and not just the substring "%g" (for example, in the case of
   * "%%g").
   *
   * @param pattern The pattern to test.
   * @param escape The escape character to search for.
   * @return True iff the pattern contains the escape sequence with the
   *  given character.
   */
  private static boolean has (final String pattern, final char escape)
  {
    final int len = pattern.length ();
    boolean sawPercent = false;
    for (int i = 0; i < len; i++)
      {
        char c = pattern.charAt (i);
        if (sawPercent)
          {
            if (c == escape)
              return true;
            if (c == '%') // Double percent
              {
                sawPercent = false;
                continue;
              }
          }
        sawPercent = (c == '%');
      }
    return false;
  }

  /**
   * An output stream that tracks the number of bytes written to it.
   */
  private final class ostr extends FilterOutputStream
  {
    private ostr (OutputStream out)
    {
      super (out);
    }

    public void write (final int b) throws IOException
    {
      out.write (b);
      FileHandler.this.written++; // FIXME: synchronize?
    }

    public void write (final byte[] b) throws IOException
    {
      write (b, 0, b.length);
    }

    public void write (final byte[] b, final int offset, final int length)
      throws IOException
    {
      out.write (b, offset, length);
      FileHandler.this.written += length; // FIXME: synchronize?
    }
  }
}