Java tutorial
/* * Copyright 2015 - 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.buffer.Unpooled; import io.netty.channel.Channel; import org.traccar.BaseProtocolDecoder; import org.traccar.DeviceSession; import org.traccar.NetworkMessage; import org.traccar.Protocol; import org.traccar.helper.DateBuilder; import org.traccar.model.CellTower; import org.traccar.model.Network; import org.traccar.model.Position; import java.net.SocketAddress; public class Avl301ProtocolDecoder extends BaseProtocolDecoder { public Avl301ProtocolDecoder(Protocol protocol) { super(protocol); } private String readImei(ByteBuf buf) { int b = buf.readUnsignedByte(); StringBuilder imei = new StringBuilder(); imei.append(b & 0x0F); for (int i = 0; i < 7; i++) { b = buf.readUnsignedByte(); imei.append((b & 0xF0) >> 4); imei.append(b & 0x0F); } return imei.toString(); } public static final int MSG_LOGIN = 'L'; public static final int MSG_STATUS = 'H'; public static final int MSG_GPS_LBS_STATUS = '$'; private void sendResponse(Channel channel, int type) { if (channel != null) { ByteBuf response = Unpooled.buffer(5); response.writeByte('$'); response.writeByte(type); response.writeByte('#'); response.writeByte('\r'); response.writeByte('\n'); channel.writeAndFlush(new NetworkMessage(response, channel.remoteAddress())); } } @Override protected Object decode(Channel channel, SocketAddress remoteAddress, Object msg) throws Exception { ByteBuf buf = (ByteBuf) msg; buf.skipBytes(1); // header int type = buf.readUnsignedByte(); buf.readUnsignedByte(); // length if (type == MSG_LOGIN) { DeviceSession deviceSession = getDeviceSession(channel, remoteAddress, readImei(buf)); if (deviceSession == null) { sendResponse(channel, type); } } else if (type == MSG_STATUS) { sendResponse(channel, type); } else if (type == MSG_GPS_LBS_STATUS) { DeviceSession deviceSession = getDeviceSession(channel, remoteAddress); if (deviceSession == null) { return null; } Position position = new Position(getProtocolName()); position.setDeviceId(deviceSession.getDeviceId()); DateBuilder dateBuilder = new DateBuilder() .setDate(buf.readUnsignedByte(), buf.readUnsignedByte(), buf.readUnsignedByte()) .setTime(buf.readUnsignedByte(), buf.readUnsignedByte(), buf.readUnsignedByte()); position.setTime(dateBuilder.getDate()); int gpsLength = buf.readUnsignedByte(); // gps len and sat position.set(Position.KEY_SATELLITES, gpsLength & 0xf); position.set(Position.KEY_SATELLITES_VISIBLE, buf.readUnsignedByte()); // satellites double latitude = buf.readUnsignedInt() / 600000.0; double longitude = buf.readUnsignedInt() / 600000.0; position.setSpeed(buf.readUnsignedByte()); int union = buf.readUnsignedShort(); // course and flags position.setCourse(union & 0x03FF); position.setValid((union & 0x1000) != 0); if ((union & 0x0400) != 0) { latitude = -latitude; } if ((union & 0x0800) != 0) { longitude = -longitude; } position.setLatitude(latitude); position.setLongitude(longitude); if ((union & 0x4000) != 0) { position.set("acc", (union & 0x8000) != 0); } position.setNetwork( new Network(CellTower.fromLacCid(buf.readUnsignedShort(), buf.readUnsignedMedium()))); position.set(Position.KEY_ALARM, Position.ALARM_GENERAL); int flags = buf.readUnsignedByte(); position.set("acc", (flags & 0x2) != 0); // parse other flags position.set(Position.KEY_POWER, buf.readUnsignedByte()); position.set(Position.KEY_RSSI, buf.readUnsignedByte()); return position; } return null; } }