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 java.util.TimeZone; import io.netty.buffer.ByteBuf; import io.netty.buffer.Unpooled; import org.traccar.BaseProtocolEncoder; import org.traccar.helper.Checksum; import org.traccar.model.Command; public class CityeasyProtocolEncoder extends BaseProtocolEncoder { private ByteBuf encodeContent(int type, ByteBuf content) { ByteBuf buf = Unpooled.buffer(); buf.writeByte('S'); buf.writeByte('S'); buf.writeShort(2 + 2 + 2 + content.readableBytes() + 4 + 2 + 2); buf.writeShort(type); buf.writeBytes(content); buf.writeInt(0x0B); buf.writeShort(Checksum.crc16(Checksum.CRC16_KERMIT, buf.nioBuffer())); buf.writeByte('\r'); buf.writeByte('\n'); return buf; } @Override protected Object encodeCommand(Command command) { ByteBuf content = Unpooled.buffer(); switch (command.getType()) { case Command.TYPE_POSITION_SINGLE: return encodeContent(CityeasyProtocolDecoder.MSG_LOCATION_REQUEST, content); case Command.TYPE_POSITION_PERIODIC: content.writeShort(command.getInteger(Command.KEY_FREQUENCY)); return encodeContent(CityeasyProtocolDecoder.MSG_LOCATION_INTERVAL, content); case Command.TYPE_POSITION_STOP: content.writeShort(0); return encodeContent(CityeasyProtocolDecoder.MSG_LOCATION_INTERVAL, content); case Command.TYPE_SET_TIMEZONE: int timezone = TimeZone.getTimeZone(command.getString(Command.KEY_TIMEZONE)).getRawOffset() / 60000; if (timezone < 0) { content.writeByte(1); } else { content.writeByte(0); } content.writeShort(Math.abs(timezone)); return encodeContent(CityeasyProtocolDecoder.MSG_TIMEZONE, content); default: return null; } } }