### Question:
Serializer extends AbstractSerializer { public static long readIndex(ByteBuffer byteBuffer) { ByteBuffer slice = byteBuffer.slice(); slice.position(6); long index = slice.getLong(); return index; }  static short readPartition(ByteBuffer byteBuffer); static long readIndex(ByteBuffer byteBuffer); static short readFlag(ByteBuffer byteBuffer); static long readSendTime(ByteBuffer byteBuffer); static void setPartition(ByteBuffer byteBuffer, short partition); static void setIndex(ByteBuffer byteBuffer, long index); static BrokerPrepare readBrokerPrepare(final ByteBuffer in); static ByteBuffer writeBrokerPrepare(BrokerPrepare prepare, ByteBuffer out); static int sizeOfBrokerPrepare(BrokerPrepare prepare); @Deprecated static ByteBuf serialize(JoyQueueLog log, ByteBuf out); static ByteBuffer serialize(JoyQueueLog log, ByteBuffer out, int size); static int sizeOf(BrokerMessage msg); static void write(final BrokerMessage message, final ByteBuffer out, int size); static void write(final BrokerMessage[] messages, final ByteBuf out); @Deprecated static void write(final BrokerMessage message, final ByteBuf out); static BrokerMessage readBrokerMessage(final ByteBuf in); static BrokerMessage readBrokerMessageHeader(ByteBuffer in); static BrokerMessage readBrokerMessage(final ByteBuffer in); static void write(final String value, final ByteBuffer out, final int lengthSize); @Deprecated static void write(final String value, final ByteBuf out, final int lengthSize); @Deprecated static void write(final String value, final ByteBuf out); static void write(final String value, final ByteBuffer out); @Deprecated static void write(final String value, final ByteBuf out, final int lengthSize,
                             final boolean compressed); static void write(final String value, final ByteBuffer out, final int lengthSize,
                             final boolean compressed); @Deprecated static void write(final int value, final ByteBuf out, final int lengthSize); static void write(final int value, final ByteBuffer out, final int lengthSize); static void write(final byte[] value, final ByteBuf out); static void write(final ByteBuffer value, final ByteBuf out); static void write(final ByteBuffer value, final ByteBuf out, final boolean writeLength); static void write(final byte[] value, final ByteBuffer out, final boolean writeLength); static void write(final ByteBuffer value, final ByteBuffer out, final boolean writeLength); @Deprecated static String readString(final ByteBuf in); @Deprecated static String readString(final ByteBuf in, final int lengthSize, final boolean compressed); @Deprecated static String read(final ByteBuf in, final int length, final boolean compressed, String charset); @Deprecated static String readString(final ByteBuf in, final int lengthSize);  }### Answer:
@Test public void readIndex() throws Exception { message.setMsgIndexNo((short) 1000); message.setClientIp(IpUtil.toByte(new InetSocketAddress(50088))); message.setText("text"); message.setAttribute("Test","TestTest"); message.setExtension("Test".getBytes()); int size = Serializer.sizeOf(message); ByteBuffer buffer = ByteBuffer.allocate(size); Serializer.write(message, buffer ,size); long index = Serializer.readIndex(buffer); Assert.assertEquals(index, 1000); }