cnzipoutputstream.java

Java实用程序设计100例(源码) Java实用程序设计100例(源码)

	case DEFLATED:
	    super.write(b, off, len);
	    break;
	case STORED:
	    written += len;
	    if (written - locoff > entry.size) {
		throw new ZipException(
		    "attempt to write past end of STORED entry");
	    }
	    out.write(b, off, len);
	    break;
	default:
	    throw new InternalError("invalid compression method");
	}
	crc.update(b, off, len);
    }

    /**
     * Finishes writing the contents of the ZIP output stream without closing
     * the underlying stream. Use this method when applying multiple filters
     * in succession to the same output stream.
     * @exception ZipException if a ZIP file error has occurred
     * @exception IOException if an I/O exception has occurred
     */
    public void finish() throws IOException {
	ensureOpen();
	if (finished) {
	    return;
	}
	if (entry != null) {
	    closeEntry();
	}
	if (entries.size() < 1) {
	    throw new ZipException("ZIP file must have at least one entry");
	}
	// write central directory
	long off = written;
	Enumeration e = entries.elements();
	while (e.hasMoreElements()) {
	    writeCEN((ZipEntry)e.nextElement());
	}
	writeEND(off, written - off);
	finished = true;
    }

    /**
     * Closes the ZIP output stream as well as the stream being filtered.
     * @exception ZipException if a ZIP file error has occurred
     * @exception IOException if an I/O error has occurred
     */
    public void close() throws IOException {
        if (!closed) {
            super.close();
            closed = true;
        }
    }

    /*
     * Writes local file (LOC) header for specified entry.
     */
    private void writeLOC(ZipEntry e) throws IOException {
	writeInt(LOCSIG);	    // LOC header signature
	writeShort(e.version);      // version needed to extract
	writeShort(e.flag);         // general purpose bit flag
	writeShort(e.method);       // compression method
	writeInt(e.time);           // last modification time
	if ((e.flag & 8) == 8) {
	    // store size, uncompressed size, and crc-32 in data descriptor
	    // immediately following compressed entry data
	    writeInt(0);
	    writeInt(0);
	    writeInt(0);
	} else {
	    writeInt(e.crc);        // crc-32
	    writeInt(e.csize);      // compressed size
	    writeInt(e.size);       // uncompressed size
	}
	byte[] nameBytes = null; 
  try 
  { 
    if (this.encoding.toUpperCase().equals("UTF-8")) 
       nameBytes =getUTF8Bytes(e.name); 
    else 
       nameBytes= e.name.getBytes(this.encoding); 
  } 
  catch(Exception byteE) 
  { 
    nameBytes=getUTF8Bytes(e.name); 
  } 

	writeShort(nameBytes.length);
	writeShort(e.extra != null ? e.extra.length : 0);
	writeBytes(nameBytes, 0, nameBytes.length);
	if (e.extra != null) {
	    writeBytes(e.extra, 0, e.extra.length);
	}
	locoff = written;
    }

    /*
     * Writes extra data descriptor (EXT) for specified entry.
     */
    private void writeEXT(ZipEntry e) throws IOException {
	writeInt(EXTSIG);	    // EXT header signature
	writeInt(e.crc);	    // crc-32
	writeInt(e.csize);	    // compressed size
	writeInt(e.size);	    // uncompressed size
    }

    /*
     * Write central directory (CEN) header for specified entry.
     * REMIND: add support for file attributes
     */
    private void writeCEN(ZipEntry e) throws IOException {
	writeInt(CENSIG);	    // CEN header signature
	writeShort(e.version);	    // version made by
	writeShort(e.version);	    // version needed to extract
	writeShort(e.flag);	    // general purpose bit flag
	writeShort(e.method);	    // compression method
	writeInt(e.time);	    // last modification time
	writeInt(e.crc);	    // crc-32
	writeInt(e.csize);	    // compressed size
	writeInt(e.size);	    // uncompressed size
	byte[] nameBytes = null; 
  try 
  { 
    if (this.encoding.toUpperCase().equals("UTF-8")) 
       nameBytes =getUTF8Bytes(e.name); 
    else 
       nameBytes= e.name.getBytes(this.encoding); 
  } 
  catch(Exception byteE) 
  { 
    nameBytes=getUTF8Bytes(e.name); 
  } 

	writeShort(nameBytes.length);
	writeShort(e.extra != null ? e.extra.length : 0);
	byte[] commentBytes;
	if (e.comment != null) {
	    commentBytes = getUTF8Bytes(e.comment);
	    writeShort(commentBytes.length);
	} else {
	    commentBytes = null;
	    writeShort(0);
	}
	writeShort(0);		    // starting disk number
	writeShort(0);		    // internal file attributes (unused)
	writeInt(0);		    // external file attributes (unused)
	writeInt(e.offset);	    // relative offset of local header
	writeBytes(nameBytes, 0, nameBytes.length);
	if (e.extra != null) {
	    writeBytes(e.extra, 0, e.extra.length);
	}
	if (commentBytes != null) {
	    writeBytes(commentBytes, 0, commentBytes.length);
	}
    }

    /*
     * Writes end of central directory (END) header.
     */
    private void writeEND(long off, long len) throws IOException {
	writeInt(ENDSIG);	    // END record signature
	writeShort(0);		    // number of this disk
	writeShort(0);		    // central directory start disk
	writeShort(entries.size()); // number of directory entries on disk
	writeShort(entries.size()); // total number of directory entries
	writeInt(len);		    // length of central directory
	writeInt(off);		    // offset of central directory
	if (comment != null) {	    // zip file comment
	    byte[] b = getUTF8Bytes(comment);
	    writeShort(b.length);
	    writeBytes(b, 0, b.length);
	} else {
	    writeShort(0);
	}
    }

    /*
     * Writes a 16-bit short to the output stream in little-endian byte order.
     */
    private void writeShort(int v) throws IOException {
	OutputStream out = this.out;
	out.write((v >>> 0) & 0xff);
	out.write((v >>> 8) & 0xff);
	written += 2;
    }

    /*
     * Writes a 32-bit int to the output stream in little-endian byte order.
     */
    private void writeInt(long v) throws IOException {
	OutputStream out = this.out;
	out.write((int)((v >>>  0) & 0xff));
	out.write((int)((v >>>  8) & 0xff));
	out.write((int)((v >>> 16) & 0xff));
	out.write((int)((v >>> 24) & 0xff));
	written += 4;
    }

    /*
     * Writes an array of bytes to the output stream.
     */
    private void writeBytes(byte[] b, int off, int len) throws IOException {
	super.out.write(b, off, len);
	written += len;
    }

    /*
     * Returns the length of String's UTF8 encoding.
     */
    static int getUTF8Length(String s) {
        int count = 0;
        for (int i = 0; i < s.length(); i++) {
            char ch = s.charAt(i); 
            if (ch <= 0x7f) {
                count++;
            } else if (ch <= 0x7ff) {
                count += 2;
            } else {
                count += 3;
            }
        }
        return count;
    }

    /*
     * Returns an array of bytes representing the UTF8 encoding
     * of the specified String.
     */
    private static byte[] getUTF8Bytes(String s) {
	char[] c = s.toCharArray();
	int len = c.length;
	// Count the number of encoded bytes...
	int count = 0;
	for (int i = 0; i < len; i++) {
	    int ch = c[i];
	    if (ch <= 0x7f) {
		count++;
	    } else if (ch <= 0x7ff) {
		count += 2;
	    } else {
		count += 3;
	    }
	}
	// Now return the encoded bytes...
	byte[] b = new byte[count];
	int off = 0;
	for (int i = 0; i < len; i++) {
	    int ch = c[i];
	    if (ch <= 0x7f) {
		b[off++] = (byte)ch;
	    } else if (ch <= 0x7ff) {
		b[off++] = (byte)((ch >> 6) | 0xc0);
		b[off++] = (byte)((ch & 0x3f) | 0x80);
	    } else {
		b[off++] = (byte)((ch >> 12) | 0xe0);
		b[off++] = (byte)(((ch >> 6) & 0x3f) | 0x80);
		b[off++] = (byte)((ch & 0x3f) | 0x80);
	    }
	}
	return b;
    }
}