Java tutorial
/* * Copyright 2012 - 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 org.traccar.helper.BufferUtil; import io.netty.buffer.ByteBuf; import io.netty.channel.Channel; import io.netty.channel.ChannelHandlerContext; public class XexunFrameDecoder extends BaseFrameDecoder { @Override protected Object decode(ChannelHandlerContext ctx, Channel channel, ByteBuf buf) throws Exception { if (buf.readableBytes() < 80) { return null; } int beginIndex = BufferUtil.indexOf("GPRMC", buf); if (beginIndex == -1) { beginIndex = BufferUtil.indexOf("GNRMC", buf); if (beginIndex == -1) { return null; } } int identifierIndex = BufferUtil.indexOf("imei:", buf, beginIndex, buf.writerIndex()); if (identifierIndex == -1) { return null; } int endIndex = buf.indexOf(identifierIndex, buf.writerIndex(), (byte) ','); if (endIndex == -1) { return null; } buf.skipBytes(beginIndex - buf.readerIndex()); return buf.readRetainedSlice(endIndex - beginIndex + 1); } }