package com.ard.work.sdk.fjr.netty;
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import io.netty.buffer.ByteBuf;
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import io.netty.channel.ChannelHandlerContext;
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import io.netty.channel.socket.DatagramPacket;
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import io.netty.handler.codec.MessageToMessageEncoder;
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import java.net.InetSocketAddress;
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import java.util.List;
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/**
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* FJR 协议编码器
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* 负责将 ThermalCommand 对象转换为符合 FJR 协议的 UDP 数据包
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*/
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public class FjrProtocolEncoder extends MessageToMessageEncoder<ThermalCommand> {
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@Override
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protected void encode(ChannelHandlerContext ctx, ThermalCommand msg, List<Object> out) throws Exception {
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// 1. 构建原始数据体：地址 + 指令ID + 数据
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// 注意：cameraId 是业务字段，不包含在协议包中
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byte[] rawData = new byte[1 + 1 + (msg.getData() != null ? msg.getData().length : 0)];
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rawData[0] = ThermalCommand.DEVICE_ADDR; // 0x26
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rawData[1] = msg.getCmdId();
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if (msg.getData() != null) {
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System.arraycopy(msg.getData(), 0, rawData, 2, msg.getData().length);
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}
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// 2. 计算校验和 (基于原始数据)
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// 规则：所有数据字节相加，取低8位
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int sum = 0;
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for (byte b : rawData) {
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sum += (b & 0xFF);
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}
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byte checkSum = (byte) (sum & 0xFF);
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// 3. 数据区转义处理
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// 规则：
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// F0 -> F5 00
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// FF -> F5 0F
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// F5 -> F5 05
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ByteBuf escapedBuf = ctx.alloc().buffer();
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for (byte b : rawData) {
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if (b == (byte) 0xF0) {
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escapedBuf.writeByte(0xF5);
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escapedBuf.writeByte(0x00);
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} else if (b == (byte) 0xFF) {
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escapedBuf.writeByte(0xF5);
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escapedBuf.writeByte(0x0F);
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} else if (b == (byte) 0xF5) {
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escapedBuf.writeByte(0xF5);
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escapedBuf.writeByte(0x05);
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} else {
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escapedBuf.writeByte(b);
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}
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}
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// 4. 组装最终数据包
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// 结构：F0(1) + Length(1) + Data(Escaped) + CheckSum(1) + FF(1)
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ByteBuf packetBuf = ctx.alloc().buffer();
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packetBuf.writeByte(0xF0); // 起始标志
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packetBuf.writeByte(rawData.length); // 数据长度 (注意：这里是原始数据的长度，不是转义后的长度)
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packetBuf.writeBytes(escapedBuf); // 转义后的数据
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packetBuf.writeByte(checkSum); // 校验和
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packetBuf.writeByte(0xFF); // 结束标志
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// 释放中间 buffer
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escapedBuf.release();
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// 5. 包装成 UDP DatagramPacket
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// 获取当前 Channel 绑定的远程地址
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InetSocketAddress remoteAddress = (InetSocketAddress) ctx.channel().remoteAddress();
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DatagramPacket packet = new DatagramPacket(packetBuf, remoteAddress);
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out.add(packet);
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// 可选：打印调试日志
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// System.out.println(">>> 发送指令: " + msg.getCmdId());
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}
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}
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