package org.yzh.protocol.codec;
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import io.github.yezhihao.protostar.Schema;
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import io.github.yezhihao.protostar.SchemaManager;
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import io.github.yezhihao.protostar.schema.RuntimeSchema;
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import io.github.yezhihao.protostar.util.ArrayMap;
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import io.github.yezhihao.protostar.util.Explain;
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import io.netty.buffer.*;
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import io.netty.util.ByteProcessor;
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import org.yzh.protocol.basics.JTMessage;
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import org.yzh.protocol.commons.JTUtils;
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import java.util.LinkedList;
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/**
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* JT协议编码器
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* @author yezhihao
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* https://gitee.com/yezhihao/jt808-server
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*/
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public class JTMessageEncoder {
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private static final ByteBufAllocator ALLOC = PooledByteBufAllocator.DEFAULT;
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private final SchemaManager schemaManager;
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private final ArrayMap<RuntimeSchema> headerSchemaMap;
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public JTMessageEncoder(String... basePackages) {
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this.schemaManager = new SchemaManager(basePackages);
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this.headerSchemaMap = schemaManager.getRuntimeSchema(JTMessage.class);
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}
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public JTMessageEncoder(SchemaManager schemaManager) {
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this.schemaManager = schemaManager;
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this.headerSchemaMap = schemaManager.getRuntimeSchema(JTMessage.class);
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}
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public ByteBuf encode(JTMessage message) {
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return encode(message, null);
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}
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public ByteBuf encode(JTMessage message, Explain explain) {
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int version = message.getProtocolVersion();
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int headLength = JTUtils.headerLength(version, false);
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int bodyLength = 0;
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Schema headSchema = headerSchemaMap.get(version);
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Schema bodySchema = schemaManager.getRuntimeSchema(message.getMessageId(), version);
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ByteBuf output;
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if (bodySchema != null) {
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output = ALLOC.buffer(headLength + bodySchema.length());
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output.writerIndex(headLength);
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bodySchema.writeTo(output, message, explain);
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bodyLength = output.writerIndex() - headLength;
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} else {
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output = ALLOC.buffer(headLength, 21);
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}
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if (bodyLength <= 1023) {
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message.setBodyLength(bodyLength);
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int writerIndex = output.writerIndex();
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if (writerIndex > 0) {
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output.writerIndex(0);
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headSchema.writeTo(output, message, explain);
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output.writerIndex(writerIndex);
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} else {
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headSchema.writeTo(output, message, explain);
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}
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output = sign(output);
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output = escape(output);
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} else {
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ByteBuf[] slices = slices(output, headLength, 1023);
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int total = slices.length;
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CompositeByteBuf _allBuf = new CompositeByteBuf(ALLOC, false, total);
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output = _allBuf;
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message.setSubpackage(true);
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message.setPackageTotal(total);
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headLength = JTUtils.headerLength(version, true);
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for (int i = 0; i < total; i++) {
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ByteBuf slice = slices[i];
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message.setPackageNo(i + 1);
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message.setBodyLength(slice.readableBytes());
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ByteBuf headBuf = ALLOC.buffer(headLength, headLength);
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headSchema.writeTo(headBuf, message, explain);
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ByteBuf msgBuf = new CompositeByteBuf(ALLOC, false, 2)
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.addComponent(true, 0, headBuf)
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.addComponent(true, 1, slice);
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msgBuf = sign(msgBuf);
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msgBuf = escape(msgBuf);
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_allBuf.addComponent(true, i, msgBuf);
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}
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}
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return output;
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}
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public static ByteBuf[] slices(ByteBuf output, int start, int unitSize) {
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int totalSize = output.writerIndex() - start;
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int tailIndex = (totalSize - 1) / unitSize;
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ByteBuf[] slices = new ByteBuf[tailIndex + 1];
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output.skipBytes(start);
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for (int i = 0; i < tailIndex; i++) {
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slices[i] = output.readSlice(unitSize);
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}
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slices[tailIndex] = output.readSlice(output.readableBytes());
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output.retain(tailIndex);
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return slices;
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}
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/** 签名 */
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public static ByteBuf sign(ByteBuf buf) {
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byte checkCode = JTUtils.bcc(buf, 0);
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buf.writeByte(checkCode);
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return buf;
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}
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private static final ByteProcessor searcher = value -> !(value == 0x7d || value == 0x7e);
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/** 转义处理 */
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public static ByteBuf escape(ByteBuf source) {
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int low = source.readerIndex();
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int high = source.writerIndex();
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LinkedList<ByteBuf> bufList = new LinkedList<>();
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int mark, len;
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while ((mark = source.forEachByte(low, high - low, searcher)) > 0) {
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len = mark + 1 - low;
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ByteBuf[] slice = slice(source, low, len);
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bufList.add(slice[0]);
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bufList.add(slice[1]);
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low += len;
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}
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if (bufList.isEmpty()) {
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bufList.add(source);
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} else {
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bufList.add(source.slice(low, high - low));
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}
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ByteBuf delimiter = Unpooled.buffer(1, 1).writeByte(0x7e).retain();
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bufList.addFirst(delimiter);
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bufList.addLast(delimiter);
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CompositeByteBuf byteBufs = new CompositeByteBuf(ALLOC, false, bufList.size());
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byteBufs.addComponents(true, bufList);
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return byteBufs;
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}
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/** 截断转义前报文，并转义 */
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protected static ByteBuf[] slice(ByteBuf byteBuf, int index, int length) {
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byte first = byteBuf.getByte(index + length - 1);
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ByteBuf[] bufs = new ByteBuf[2];
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bufs[0] = byteBuf.retainedSlice(index, length);
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if (first == 0x7d) {
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bufs[1] = Unpooled.buffer(1, 1).writeByte(0x01);
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} else {
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byteBuf.setByte(index + length - 1, 0x7d);
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bufs[1] = Unpooled.buffer(1, 1).writeByte(0x02);
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}
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return bufs;
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}
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}
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