Java tutorial
/* * Copyright 2016 - 2018 Anton Tananaev (anton@traccar.org) * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.traccar.protocol; import io.netty.buffer.ByteBuf; import io.netty.channel.Channel; import io.netty.channel.ChannelHandlerContext; import org.traccar.BaseFrameDecoder; import org.traccar.helper.BufferUtil; public class GranitFrameDecoder extends BaseFrameDecoder { @Override protected Object decode(ChannelHandlerContext ctx, Channel channel, ByteBuf buf) throws Exception { int indexEnd = BufferUtil.indexOf("\r\n", buf); if (indexEnd != -1) { int indexTilde = buf.indexOf(buf.readerIndex(), buf.writerIndex(), (byte) '~'); if (indexTilde != -1 && indexTilde < indexEnd) { int length = buf.getUnsignedShortLE(indexTilde + 1); indexEnd = BufferUtil.indexOf("\r\n", buf, indexTilde + 2 + length, buf.writerIndex()); if (indexEnd == -1) { return null; } } ByteBuf frame = buf.readRetainedSlice(indexEnd - buf.readerIndex()); buf.skipBytes(2); return frame; } return null; } }