进制转化的一些疑惑 about mysql-protocol HOT 4 OPEN

public long readUB4() {
		final byte[] b = this.data;
		long l = (long) (b[position++] & 0xff);
		l |= (long) (b[position++] & 0xff) << 8;
		l |= (long) (b[position++] & 0xff) << 16;
		l |= (long) (b[position++] & 0xff) << 24;
		return l;
	}

public static final void writeUB3(ByteBuffer buffer, int i) {
		buffer.put((byte) (i & 0xff));
		buffer.put((byte) (i >>> 8));
		buffer.put((byte) (i >>> 16));
	}