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 org.traccar.BaseProtocolEncoder; import org.traccar.Context; import org.traccar.helper.Checksum; import org.traccar.model.Command; import java.nio.charset.StandardCharsets; public class Gt06ProtocolEncoder extends BaseProtocolEncoder { private ByteBuf encodeContent(long deviceId, String content) { boolean language = Context.getIdentityManager().lookupAttributeBoolean(deviceId, "gt06.language", false, true); ByteBuf buf = Unpooled.buffer(); buf.writeByte(0x78); buf.writeByte(0x78); buf.writeByte(1 + 1 + 4 + content.length() + 2 + 2 + (language ? 2 : 0)); // message length buf.writeByte(0x80); // message type buf.writeByte(4 + content.length()); // command length buf.writeInt(0); buf.writeBytes(content.getBytes(StandardCharsets.US_ASCII)); // command if (language) { buf.writeShort(2); // english language } buf.writeShort(0); // message index buf.writeShort(Checksum.crc16(Checksum.CRC16_X25, buf.nioBuffer(2, buf.writerIndex() - 2))); buf.writeByte('\r'); buf.writeByte('\n'); return buf; } @Override protected Object encodeCommand(Command command) { boolean alternative = Context.getIdentityManager().lookupAttributeBoolean(command.getDeviceId(), "gt06.alternative", false, true); switch (command.getType()) { case Command.TYPE_ENGINE_STOP: return encodeContent(command.getDeviceId(), alternative ? "DYD,123456#" : "Relay,1#"); case Command.TYPE_ENGINE_RESUME: return encodeContent(command.getDeviceId(), alternative ? "HFYD,123456#" : "Relay,0#"); case Command.TYPE_CUSTOM: return encodeContent(command.getDeviceId(), command.getString(Command.KEY_DATA)); default: return null; } } }