netty自定義解碼器

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());
 }
 }
}

關鍵字: in.readableBytes logger.info publ