Java tutorial
/* * Copyright 2017 - 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 org.traccar.BaseFrameDecoder; import io.netty.buffer.ByteBuf; import io.netty.buffer.Unpooled; import io.netty.channel.Channel; import io.netty.channel.ChannelHandlerContext; public class Vt200FrameDecoder extends BaseFrameDecoder { @Override protected Object decode(ChannelHandlerContext ctx, Channel channel, ByteBuf buf) throws Exception { int endIndex = buf.indexOf(buf.readerIndex(), buf.writerIndex(), (byte) ')') + 1; if (endIndex > 0) { ByteBuf frame = Unpooled.buffer(); while (buf.readerIndex() < endIndex) { int b = buf.readByte(); if (b == '=') { frame.writeByte(buf.readByte() ^ '='); } else { frame.writeByte(b); } } return frame; } return null; } }