netty自定義解碼器
實現自定義開始結束標誌符，實現TCP粘包，拆包。
使用方法：
ch.pipeline().addLast(new MyDecoder(開始標誌符,結束標誌符);
源碼如下：
package com.ljy.iot.decoder; import io.netty.buffer.ByteBuf; import io.netty.channel.ChannelHandlerContext; import io.netty.handler.codec.ByteToMessageDecoder; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.util.List; /** * @author : 夕 * @date : 2019/8/31 */ public class MyDecoder extends ByteToMessageDecoder { private byte start; private byte end; public MyDecoder(){ } public MyDecoder(byte start,byte end){ this.start = start; this.end = end; } private static Logger logger = LoggerFactory.getLogger(MyDecoder.class); @Override protected void decode(ChannelHandlerContext ctx, ByteBuf in, List out) throws Exception { logger.info("進入Decoder的ByteBuf.readableBytes(): " + in.readableBytes()); if(start != end){ int length = in.readableBytes(); int start_flag = in.indexOf(0,length,start); int end_flag = in.indexOf(0,length,end); logger.info("start_flag: "+ start_flag + "; end_flag: " + end_flag); if( (start_flag >= 0 && end_flag >= 0) && ((end_flag - start_flag) > 0) ){ out.add(in.copy(start_flag,end_flag - start_flag + 1)); in.skipBytes(in.readableBytes()); } logger.info("退出Decoder的ByteBuf.readableBytes(): " + in.readableBytes()); }else { int length = in.readableBytes(); int start_flag = in.indexOf(0,length,start); if(start_flag < 0) { logger.info("退出Decoder的ByteBuf.readableBytes(): " + in.readableBytes()); return; } int end_flag = in.indexOf(start_flag+1,length-start_flag,end); if(end_flag > start_flag){ logger.info("start_flag: "+ start_flag + "; end_flag: " + end_flag); out.add(in.copy(start_flag,end_flag - start_flag + 1)); in.skipBytes(in.readableBytes()); } logger.info("退出Decoder的ByteBuf.readableBytes(): " + in.readableBytes()); } } }