netty客户端与服务端例子

package com.snailteam.netty;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;

/**
 * 服务端Bootstrap
 * @author  
 *
 */
public class NServer {
	static final int PORT = 8080; 

	public static void main(String[] args) {
		EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
             .channel(NioServerSocketChannel.class)
             .childHandler(new ChannelInitializer<SocketChannel>() {
                @Override
                public void initChannel(SocketChannel ch) throws Exception {
                         /**
                	Inbound: 1 ->2 ->3 ->n 顺序处理 
			Outbound: n ->n-1 ->n-2 .. ->1  逆序处理
                	 */
                	//new LengthFieldBasedFrameDecoder(1024*8*20, 0, 4,0,4) 最大1024*8*20位为接收数据包，从0，长4Byte是数据宽度，然后从0，长4Byte剔除后的byte数据包，传送 到后面的handler链处理
                	ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG),new LengthFieldBasedFrameDecoder(1024*8*20, 0, 4,0,4), new NServerHandler());
                }
             });

            // Bind and start to accept incoming connections.
            b.bind(PORT).sync().channel().closeFuture().sync();
        } catch (InterruptedException e) {
			e.printStackTrace();
		} finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
	}
}

package com.snailteam.netty;

import java.nio.charset.Charset;

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

public class NServerHandler extends SimpleChannelInboundHandler<ByteBuf> {


	@Override
	public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
		cause.printStackTrace();
		ctx.close();
	}

	@Override
	protected void channelRead0(ChannelHandlerContext ctx, ByteBuf msg)
			throws Exception {
		String str = msg.toString(Charset.forName("UTF-8"));
		System.out.println("[ok]" +str );
		str = "辛苦了"+str.substring(str.lastIndexOf(',')+1);
		ctx.writeAndFlush(Unpooled.wrappedBuffer(str.getBytes()));
	}
}

package com.snailteam.netty;

import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.Channel;
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.LengthFieldPrepender;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
/**
 * 客户端Bootstrap
 *
 */
public class Nclient {
	public static void main(String[] args) {
		EventLoopGroup group = new NioEventLoopGroup();
		try {
			Bootstrap b = new Bootstrap();
			b.group(group).channel(NioSocketChannel.class).option(ChannelOption.TCP_NODELAY, true)
					.handler(new ChannelInitializer<SocketChannel>() {
						@Override
						public void initChannel(SocketChannel ch)
								throws Exception {
							//LengthFieldPrepender 把发送的数据前加4Byte存储数据宽度，发送。
							ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG),new LengthFieldPrepender(4),
									new NclientHandler());

						}
					});

			StringBuilder sb = new StringBuilder();
			for (int i = 0; i < 20; i++) {
				sb.append("中华人民共和国" + i + ",");
			}
			// Bind and start to accept incoming connections.
			Channel con = b.connect("localhost", NServer.PORT).sync().channel();
			
			for (int i = 0; i < 900; i++) {
				String str = sb.toString() + i; 
				con.writeAndFlush(Unpooled.wrappedBuffer(str.getBytes())).sync().get();
				System.out.println(i);
			}
			con.close().sync();//异步退出
		} catch (InterruptedException e) {
			e.printStackTrace();
		} finally {
			group.shutdownGracefully();
		}
	}
}

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package com.snailteam.netty;

import java.nio.charset.Charset;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;

public class NclientHandler extends SimpleChannelInboundHandler<ByteBuf> {
	
	@Override
    public void exceptionCaught(
            ChannelHandlerContext ctx, Throwable cause) throws Exception {
		cause.printStackTrace();
        ctx.close();
    }
	@Override
	protected void channelRead0(ChannelHandlerContext ctx, ByteBuf msg)
			throws Exception {
		System.out.println(msg.toString(Charset.forName("UTF-8")));
		
	}
}

package com.snailteam.netty;

import java.util.List;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;
 

public class FrameDecoder extends ByteToMessageDecoder{
	int lengthFeildLength = 4;
	
	@Override
	protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
		 Object decoded = decode(ctx, in);
	        if (decoded != null) {
	            out.add(decoded);
	        }
	}

	private Object decode(ChannelHandlerContext ctx, ByteBuf in) {
		if(in.readableBytes()<lengthFeildLength)return null;//
		int index = in.readerIndex();
		int len = in.readInt();//解析次数包中对象的大小
		if(in.readableBytes()<len){//数据包的内容不全
			in.readerIndex(index);//重置readerIndex 
			return null;
		}
		return in.readRetainedSlice(len);//截取完整的一个转码对象。
	}

}

pom

<dependency>
			<groupId>io.netty</groupId>
			<artifactId>netty-example</artifactId>
			<version>4.1.6.Final</version>
			<exclusions>
				<exclusion>
					<artifactId>netty-tcnative</artifactId>
					<groupId>io.netty</groupId>
				</exclusion>
			</exclusions>
		</dependency>
		<dependency>
			<groupId>io.netty</groupId>
			<artifactId>netty-tcnative</artifactId>
			<version>1.1.33.Fork23</version>
			<classifier>windows-x86_64</classifier>
		</dependency>