Java tutorial
/* * Copyright 2013 - 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 org.traccar.BaseProtocolDecoder; import org.traccar.DeviceSession; import org.traccar.Protocol; import org.traccar.helper.DateBuilder; import org.traccar.model.Position; import java.net.SocketAddress; public class M2mProtocolDecoder extends BaseProtocolDecoder { public M2mProtocolDecoder(Protocol protocol) { super(protocol); } private boolean firstPacket = true; @Override protected Object decode(Channel channel, SocketAddress remoteAddress, Object msg) throws Exception { ByteBuf buf = (ByteBuf) msg; // Remove offset for (int i = 0; i < buf.readableBytes(); i++) { int b = buf.getByte(i); if (b != 0x0b) { buf.setByte(i, b - 0x20); } } if (firstPacket) { firstPacket = false; StringBuilder imei = new StringBuilder(); for (int i = 0; i < 8; i++) { int b = buf.readByte(); if (i != 0) { imei.append(b / 10); } imei.append(b % 10); } getDeviceSession(channel, remoteAddress, imei.toString()); } else { DeviceSession deviceSession = getDeviceSession(channel, remoteAddress); if (deviceSession == null) { return null; } Position position = new Position(getProtocolName()); position.setDeviceId(deviceSession.getDeviceId()); DateBuilder dateBuilder = new DateBuilder().setDay(buf.readUnsignedByte() & 0x3f) .setMonth(buf.readUnsignedByte() & 0x3f).setYear(buf.readUnsignedByte()) .setHour(buf.readUnsignedByte() & 0x3f).setMinute(buf.readUnsignedByte() & 0x7f) .setSecond(buf.readUnsignedByte() & 0x7f); position.setTime(dateBuilder.getDate()); int degrees = buf.readUnsignedByte(); double latitude = buf.readUnsignedByte(); latitude += buf.readUnsignedByte() / 100.0; latitude += buf.readUnsignedByte() / 10000.0; latitude /= 60; latitude += degrees; int b = buf.readUnsignedByte(); degrees = (b & 0x7f) * 100 + buf.readUnsignedByte(); double longitude = buf.readUnsignedByte(); longitude += buf.readUnsignedByte() / 100.0; longitude += buf.readUnsignedByte() / 10000.0; longitude /= 60; longitude += degrees; if ((b & 0x80) != 0) { longitude = -longitude; } if ((b & 0x40) != 0) { latitude = -latitude; } position.setValid(true); position.setLatitude(latitude); position.setLongitude(longitude); position.setSpeed(buf.readUnsignedByte()); int satellites = buf.readUnsignedByte(); if (satellites == 0) { return null; // cell information } position.set(Position.KEY_SATELLITES, satellites); // decode other data return position; } return null; } }