Netty实现Tcp客户端

1、client类  建立socket连接，发送报文请求服务端

package com.bokeyuan.client;

import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import java.nio.charset.Charset;

public class Client {

   
   public static void main(String[] args) {
      /**调用netty客户端*/
      doRequest();
   }

   private static void doRequest(){
      /**处理请求和服务端响应数据的线程组*/
      EventLoopGroup workerGroup = new NioEventLoopGroup();
      try {
         /**客户端相关配置信息*/
         Bootstrap bootstrap = new Bootstrap();
         //绑定线程组
         bootstrap.group(workerGroup);
         bootstrap.channel(NioSocketChannel.class);
         bootstrap.option(ChannelOption.SO_KEEPALIVE, true);
         /*
          * 客户端必须绑定处理器，也就是必须调用handler方法
          */
         bootstrap.handler(new ChannelInitializer<SocketChannel>() {
            @Override
            protected void initChannel(SocketChannel ch) throws Exception {
               ch.pipeline().addLast(new ClientHandler());
            }
         });

         ChannelFuture future = bootstrap.connect("192.169.1.165", 8091).sync();
         //请求报文
         String msg="0010awesdfgtyh";
         byte[] data = msg.getBytes("GBK");
         ByteBuf byteBufMsg = Unpooled.buffer();
         byteBufMsg.writeBytes(data);
         future.channel().writeAndFlush(byteBufMsg);

         future.channel().closeFuture().sync();
      } catch (InterruptedException e) {
         e.printStackTrace();
      }finally{
         workerGroup.shutdownGracefully();
      } 
   }
}

2、ClientHandler类 处理服务端响应报文

 继承ChannelInboundHandlerAdapter 类

package com.bokeyuan.client;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;

import java.io.UnsupportedEncodingException;



public class ClientHandler extends ChannelInboundHandlerAdapter {

   @Override
   public void channelRead(ChannelHandlerContext ctx, Object msg)
         throws Exception {
      try{
         ByteBuf buf = (ByteBuf) msg;
         String rev = getMessage(buf);
         System.out.println("响应报文:" + rev);
      }catch (Exception e){
         e.printStackTrace();
      }

   }

   private String getMessage(ByteBuf buf) {
      byte[] con = new byte[buf.readableBytes()];
      buf.readBytes(con);
      try {
         return new String(con, "GBK");
      } catch (UnsupportedEncodingException e) {
         e.printStackTrace();
         return null;
      }
   }
}

其他写法

1、改成在ClientHandler类(继承了ChannelInboundHandlerAdapter)中发送请求报文

• 1、覆写父类channelActive方法，在此方法中调用ctx.writeAndFlush()发送请求报文

　　(客户端与服务端建立连接时会执行channelActive方法)

 　　

•  2、去掉Client类中的future.channel().wirteAndFlush()代码

 　　

 

2、直接传报文字符串，不将报文转为ByteBuf,即channel.writeAndFlush(报文字符串)

•  1.1、innitChannel中添加字符串解码器，字符串编码器

•  1.2、future.channel().writeAndFlush(msg)中 ,msg直接传原始报文内容，不需要转为ByteBuf

　　

•  1.3、ClientHandler类的channelRead方法，不需要将msg由Bytebuf转为String