zipfile.java

gcc的组建

	  {
	    byte[] extra = new byte[extraLen];
	    raf.readFully(extra);
	    entry.setExtra(extra);
	  }
	if (commentLen > 0)
	  {
	    raf.readFully(buffer, 0, commentLen);
	    try
	      {
		entry.setComment(new String(buffer, 0, commentLen, "UTF-8"));
	      }
	    catch (UnsupportedEncodingException uee)
	      {
		throw new AssertionError(uee);
	      }
	  }
	entry.offset = offset;
	entries.put(name, entry);
      }
  }

  /**
   * Closes the ZipFile.  This also closes all input streams given by
   * this class.  After this is called, no further method should be
   * called.
   * 
   * @exception IOException if a i/o error occured.
   */
  public void close() throws IOException
  {
    RandomAccessFile raf = this.raf;
    if (raf == null)
      return;

    synchronized (raf)
      {
	closed = true;
	entries = null;
	raf.close();
      }
  }

  /**
   * Calls the <code>close()</code> method when this ZipFile has not yet
   * been explicitly closed.
   */
  protected void finalize() throws IOException
  {
    if (!closed && raf != null) close();
  }

  /**
   * Returns an enumeration of all Zip entries in this Zip file.
   *
   * @exception IllegalStateException when the ZipFile has already been closed
   */
  public Enumeration entries()
  {
    checkClosed();
    
    try
      {
	return new ZipEntryEnumeration(getEntries().values().iterator());
      }
    catch (IOException ioe)
      {
	return EmptyEnumeration.getInstance();
      }
  }

  /**
   * Checks that the ZipFile is still open and reads entries when necessary.
   *
   * @exception IllegalStateException when the ZipFile has already been closed.
   * @exception IOException when the entries could not be read.
   */
  private HashMap getEntries() throws IOException
  {
    synchronized(raf)
      {
	checkClosed();

	if (entries == null)
	  readEntries();

	return entries;
      }
  }

  /**
   * Searches for a zip entry in this archive with the given name.
   *
   * @param name the name. May contain directory components separated by
   * slashes ('/').
   * @return the zip entry, or null if no entry with that name exists.
   *
   * @exception IllegalStateException when the ZipFile has already been closed
   */
  public ZipEntry getEntry(String name)
  {
    checkClosed();

    try
      {
	HashMap entries = getEntries();
	ZipEntry entry = (ZipEntry) entries.get(name);
        // If we didn't find it, maybe it's a directory.
        if (entry == null && !name.endsWith("/"))
            entry = (ZipEntry) entries.get(name + '/');
	return entry != null ? new ZipEntry(entry, name) : null;
      }
    catch (IOException ioe)
      {
	return null;
      }
  }


  //access should be protected by synchronized(raf)
  private byte[] locBuf = new byte[LOCHDR];

  /**
   * Checks, if the local header of the entry at index i matches the
   * central directory, and returns the offset to the data.
   * 
   * @param entry to check.
   * @return the start offset of the (compressed) data.
   *
   * @exception IOException if a i/o error occured.
   * @exception ZipException if the local header doesn't match the 
   * central directory header
   */
  private long checkLocalHeader(ZipEntry entry) throws IOException
  {
    synchronized (raf)
      {
	raf.seek(entry.offset);
	raf.readFully(locBuf);
	
	if (readLeInt(locBuf, 0) != LOCSIG)
	  throw new ZipException("Wrong Local header signature: " + name);

	if (entry.getMethod() != readLeShort(locBuf, LOCHOW))
	  throw new ZipException("Compression method mismatch: " + name);

	if (entry.getName().length() != readLeShort(locBuf, LOCNAM))
	  throw new ZipException("file name length mismatch: " + name);

	int extraLen = entry.getName().length() + readLeShort(locBuf, LOCEXT);
	return entry.offset + LOCHDR + extraLen;
      }
  }

  /**
   * Creates an input stream reading the given zip entry as
   * uncompressed data.  Normally zip entry should be an entry
   * returned by getEntry() or entries().
   *
   * This implementation returns null if the requested entry does not
   * exist.  This decision is not obviously correct, however, it does
   * appear to mirror Sun's implementation, and it is consistant with
   * their javadoc.  On the other hand, the old JCL book, 2nd Edition,
   * claims that this should return a "non-null ZIP entry".  We have
   * chosen for now ignore the old book, as modern versions of Ant (an
   * important application) depend on this behaviour.  See discussion
   * in this thread:
   * http://gcc.gnu.org/ml/java-patches/2004-q2/msg00602.html
   *
   * @param entry the entry to create an InputStream for.
   * @return the input stream, or null if the requested entry does not exist.
   *
   * @exception IllegalStateException when the ZipFile has already been closed
   * @exception IOException if a i/o error occured.
   * @exception ZipException if the Zip archive is malformed.  
   */
  public InputStream getInputStream(ZipEntry entry) throws IOException
  {
    checkClosed();

    HashMap entries = getEntries();
    String name = entry.getName();
    ZipEntry zipEntry = (ZipEntry) entries.get(name);
    if (zipEntry == null)
      return null;

    long start = checkLocalHeader(zipEntry);
    int method = zipEntry.getMethod();
    InputStream is = new BufferedInputStream(new PartialInputStream
      (raf, start, zipEntry.getCompressedSize()));
    switch (method)
      {
      case ZipOutputStream.STORED:
	return is;
      case ZipOutputStream.DEFLATED:
	return new InflaterInputStream(is, new Inflater(true));
      default:
	throw new ZipException("Unknown compression method " + method);
      }
  }
  
  /**
   * Returns the (path) name of this zip file.
   */
  public String getName()
  {
    return name;
  }

  /**
   * Returns the number of entries in this zip file.
   *
   * @exception IllegalStateException when the ZipFile has already been closed
   */
  public int size()
  {
    checkClosed();
    
    try
      {
	return getEntries().size();
      }
    catch (IOException ioe)
      {
	return 0;
      }
  }
  
  private static class ZipEntryEnumeration implements Enumeration
  {
    private final Iterator elements;

    public ZipEntryEnumeration(Iterator elements)
    {
      this.elements = elements;
    }

    public boolean hasMoreElements()
    {
      return elements.hasNext();
    }

    public Object nextElement()
    {
      /* We return a clone, just to be safe that the user doesn't
       * change the entry.  
       */
      return ((ZipEntry)elements.next()).clone();
    }
  }

  private static class PartialInputStream extends InputStream
  {
    private final RandomAccessFile raf;
    long filepos, end;

    public PartialInputStream(RandomAccessFile raf, long start, long len)
    {
      this.raf = raf;
      filepos = start;
      end = start + len;
    }
    
    public int available()
    {
      long amount = end - filepos;
      if (amount > Integer.MAX_VALUE)
	return Integer.MAX_VALUE;
      return (int) amount;
    }
    
    public int read() throws IOException
    {
      if (filepos == end)
	return -1;
      synchronized (raf)
	{
	  raf.seek(filepos++);
	  return raf.read();
	}
    }

    public int read(byte[] b, int off, int len) throws IOException
    {
      if (len > end - filepos)
	{
	  len = (int) (end - filepos);
	  if (len == 0)
	    return -1;
	}
      synchronized (raf)
	{
	  raf.seek(filepos);
	  int count = raf.read(b, off, len);
	  if (count > 0)
	    filepos += len;
	  return count;
	}
    }

    public long skip(long amount)
    {
      if (amount < 0)
	throw new IllegalArgumentException();
      if (amount > end - filepos)
	amount = end - filepos;
      filepos += amount;
      return amount;
    }
  }
}