public static void writeCompress(String fin, String fout) {
		BufferedInputStream in =null;
		BufferedOutputStream out =null;
		byte[] buf =new byte[8];
		int len =-1;
		try {
			in =new BufferedInputStream(new FileInputStream(fin));
			out =new BufferedOutputStream(new FileOutputStream(fout));
			long l1 =0, l2 =0, t =new File(fin).length()/8;
			out.write(longToBytes(t));
			while ((len =in.read(buf)) !=-1) {
				if (len ==8) {
					l2 =BytesToLong(buf, len);
					System.out.println("差分编码：" +getBitString(l2));
					//writeVLong(l2 -l1, out);
					writeVLong(l2 -0xffffffffffL, out);
					l1 =l2;
				} 
				else {
					out.write(buf, 0, len);
				}
			}
			
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
				try {
					if (in !=null) in.close();
					if (out !=null) out.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
		}
	}