netty权威指南学习

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1、Bio工程结构
maven工程文件结构：
│ nettyArticle.iml
│ pom.xml
│
├─.idea
│ compiler.xml
│ misc.xml
│ vcs.xml
│ workspace.xml
│
├─src
│ ├─main
│ │ ├─java
│ │ │ └─com
│ │ │ └─jad
│ │ │ └─nettyArticle
│ │ │ ├─aio
│ │ │ │ AcceptCompletionHandler.java
│ │ │ │ AioTimeClient.java
│ │ │ │ AioTimeServer.java
│ │ │ │ AsyncTimeClientHandler.java
│ │ │ │ AysncTimeServerHandler.java
│ │ │ │ ReadCompletionHandler.java
│ │ │ │
│ │ │ ├─bio
│ │ │ │ TimeClient.java
│ │ │ │ TimeServer.java
│ │ │ │ TimeServerHandler.java
│ │ │ │
│ │ │ ├─fakeNio
│ │ │ │ FakeNioTimeServer.java
│ │ │ │ TimeServerHandlerExecutePool.java
│ │ │ │
│ │ │ ├─netty
│ │ │ │ NettyTimeClient.java
│ │ │ │ NettyTimeClientHandler.java
│ │ │ │ NettyTimeServer.java
│ │ │ │ NettyTimeServerHandler.java
│ │ │ │
│ │ │ └─nio
│ │ │ MultiplexerTimeServer.java
│ │ │ NioTimeClient.java
│ │ │ NioTimeServer.java
│ │ │ TimeClientHandler.java
│ │ │
│ │ └─resources
│ └─test
│ └─java
└─target
├─classes
│ └─com
│ └─jad
│ └─nettyArticle
│ ├─aio
│ │ AcceptCompletionHandler.class
│ │ AioTimeClient.class
│ │ AioTimeServer.class
│ │ AsyncTimeClientHandler$1$1.class
│ │ AsyncTimeClientHandler$1.class
│ │ AsyncTimeClientHandler.class
│ │ AysncTimeServerHandler.class
│ │ ReadCompletionHandler$1.class
│ │ ReadCompletionHandler.class
│ │
│ ├─bio
│ │ TimeClient.class
│ │ TimeServer.class
│ │ TimeServerHandler.class
│ │
│ ├─fakeNio
│ │ FakeNioTimeServer.class
│ │ TimeServerHandlerExecutePool.class
│ │
│ ├─netty
│ │ NettyTimeClient$1.class
│ │ NettyTimeClient.class
│ │ NettyTimeClientHandler.class
│ │ NettyTimeServer$1.class││NettyTimeServer$ChildChannelHandler.class
│ │ NettyTimeServer.class
│ │ NettyTimeServerHandler.class
│ │
│ └─nio
│ MultiplexerTimeServer.class
│ NioTimeClient.class
│ NioTimeServer.class
│ TimeClientHandler.class
│
└─generated-sources
└─annotations

2、代码：
pom.xml：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.jad</groupId>
    <artifactId>nettyArticle</artifactId>
    <version>1.0-SNAPSHOT</version>


</project>

TimeServer：

package com.jad.nettyArticle.bio;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;

public class TimeServer { 
   
    public static void main(String[] args) throws IOException { 
   
        int port=8080;
        if(args!=null && args.length>0) { 
   
            try { 
   
                port = Integer.valueOf(args[0]);
            } catch (NumberFormatException e) { 
   
                e.printStackTrace();
            }
        }
            ServerSocket server =null;

            try { 
   
                server=new ServerSocket(port);
                System.out.println("The time server is start in port :"+port);
                Socket socket=null;
                while (true) { 
   
                    socket = server.accept();
                    new Thread(new TimeServerHandler(socket)).start();
                }
            } finally { 
   
                if (server != null) { 
   
                    System.out.println("The time server close");
                    server.close();
                    server=null;
                }
            }
    }
}

TimeServerHandler：

package com.jad.nettyArticle.bio;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
public class TimeServerHandler implements Runnable { 

private Socket socket;
public TimeServerHandler(Socket socket) { 

this.socket=socket;
}
public void run() { 

BufferedReader in = null;
PrintWriter out = null;
try { 

in = new BufferedReader(new InputStreamReader(this.socket.getInputStream()));
out= new PrintWriter(this.socket.getOutputStream(),true);
String currentTime = null;
String body = null;
while (true) { 

body=in.readLine();
if (body == null) { 

break;
}
System.out.println("The time server receive order :"+body);
currentTime="QUERY TIME ORDER".equalsIgnoreCase(body)?new java.util.Date(
System.currentTimeMillis()).toString():"BAD ORDER";
out.println(currentTime);
}
} catch (IOException e) { 

if (in != null) { 

try { 

in.close();
} catch (IOException ex) { 

ex.printStackTrace();
}
}
if (out != null) { 

out.close();
out = null;
}
if (this.socket != null) { 

try { 

this.socket.close();
} catch (IOException ex) { 

ex.printStackTrace();
}
this.socket= null;
}
}
}
}

TimeClient：

package com.jad.nettyArticle.bio;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
public class TimeClient { 

public static void main(String[] args) { 

int port = 8080;
if (args!=null && args.length>0) { 

try { 

port = Integer.valueOf(args[0]);
} catch (NumberFormatException e) { 

e.printStackTrace();
}
}
Socket socket = null;
BufferedReader in = null;
PrintWriter out = null;
try { 

socket = new Socket("127.0.0.1",port);
in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
out = new PrintWriter(socket.getOutputStream(),true);
out.println("QUERY TIME ORDER");
System.out.println("Send order 2 server succeed.");
String resp = in.readLine();
System.out.println("Now is :"+resp);
} catch (IOException e) { 

e.printStackTrace();
} finally { 

if (out != null) { 

out.close();
out = null;
}
if (in != null) { 

try { 

in.close();
} catch (IOException e) { 

e.printStackTrace();
}
in = null;
}
if (socket != null) { 

try { 

socket.close();
} catch (IOException e) { 

e.printStackTrace();
}
socket = null;
}
}
}
}

FakeNioTimeServer：

package com.jad.nettyArticle.fakeNio;
import com.jad.nettyArticle.bio.TimeServerHandler;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
public class FakeNioTimeServer { 

public static void main(String[] args) throws IOException { 

int port=8080;
if(args!=null && args.length>0) { 

try { 

port = Integer.valueOf(args[0]);
} catch (NumberFormatException e) { 

e.printStackTrace();
}
}
ServerSocket server =null;
try { 

server=new ServerSocket(port);
System.out.println("The time server is start in port :"+port);
Socket socket=null;
TimeServerHandlerExecutePool singleExecutor = new TimeServerHandlerExecutePool(50,100);
while (true) { 

socket = server.accept();
//new Thread(new TimeServerHandler(socket)).start();
singleExecutor.execute(new TimeServerHandler(socket));
}
} finally { 

if (server != null) { 

System.out.println("The time server close");
server.close();
server=null;
}
}
}
}

TimeServerHandlerExecutePool：

package com.jad.nettyArticle.fakeNio;
import com.jad.nettyArticle.bio.TimeServerHandler;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
public class TimeServerHandlerExecutePool { 

private ExecutorService executor;
public TimeServerHandlerExecutePool(int maxPoolSize , int queueSize) { 

executor = new ThreadPoolExecutor(Runtime.getRuntime().availableProcessors(),maxPoolSize,
120L, TimeUnit.SECONDS,new ArrayBlockingQueue<java.lang.Runnable>(queueSize));
}
public void execute(TimeServerHandler timeServerHandler) { 

executor.execute(timeServerHandler);
}
}

NioTimeServer：

package com.jad.nettyArticle.nio;
public class NioTimeServer { 

public static void main(String[] args) { 

int port=8080;
if(args!=null && args.length>0) { 

try { 

port = Integer.valueOf(args[0]);
} catch (NumberFormatException e) { 

e.printStackTrace();
}
}
MultiplexerTimeServer timeServer=new MultiplexerTimeServer(port);
new Thread(timeServer,"NIO-MultiplexerTimeServer-001").start();
}
}

MultiplexerTimeServer：

package com.jad.nettyArticle.nio;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;
public class MultiplexerTimeServer implements Runnable{ 

private Selector selector;
private ServerSocketChannel serverChannel;
private volatile boolean stop = false;
public MultiplexerTimeServer(int port) { 

try { 

selector=Selector.open();
serverChannel=ServerSocketChannel.open();
serverChannel.configureBlocking(false);
serverChannel.socket().bind(new InetSocketAddress(port),1024);
serverChannel.register(selector, SelectionKey.OP_ACCEPT);
System.out.println("The time server is start in port:"+port);
} catch (IOException e) { 

e.printStackTrace();
System.exit(1);
}
}
public  void  stop(){ 

this.stop = true;
}
public void run() { 

while (!stop) { 

try { 

System.out.println("The server thread is running");
selector.select(1000);
Set<SelectionKey> selectionKeys = selector.selectedKeys();
Iterator<SelectionKey> it = selectionKeys.iterator();
System.out.println("The keys is :"+it);
SelectionKey key = null;
while (it.hasNext()) { 

key=it.next();
it.remove();
try { 

System.out.println("handle key is :"+key+" start");
handleInput(key);
System.out.println("handle key is :"+key+" end");
} catch (Exception e) { 

e.printStackTrace();
if (key != null) { 

key.cancel();
if (key.channel() != null) { 

key.channel().close();
}
}
}
}
} catch (IOException e) { 

e.printStackTrace();
}
}
if (selector != null) { 

try { 

selector.close();
} catch (IOException e) { 

e.printStackTrace();
}
}
}
private void handleInput(SelectionKey key) throws IOException { 

System.out.println("handling key is :"+key+" start");
if (key.isValid()) { 

System.out.println("key :"+key+" valided");
//SocketChannel sc = null;
if (key.isAcceptable()) { 

System.out.println("key :"+key+" be accepted");
ServerSocketChannel ssc = (ServerSocketChannel)key.channel();
SocketChannel sc = ssc.accept();
sc.configureBlocking(false);
sc.register(selector,SelectionKey.OP_READ);
System.out.println("channel related to key :"+key+" register read operation!");
}
if (key.isReadable()) { 

System.out.println("key :"+key+" can be read !");
SocketChannel sc = (SocketChannel)key.channel();
ByteBuffer readBuffer = ByteBuffer.allocate(1024);
int readBytes = sc.read(readBuffer);
System.out.println("channel related to key :"+key+" length is "+readBytes);
if (readBytes>0) { 

readBuffer.flip();
byte[] bytes = new byte[readBuffer.remaining()];
readBuffer.get(bytes);
String body = new String(bytes,"UTF-8");
System.out.println("The time server receive order :"+body);
String currentTime="QUERY TIME ORDER".equalsIgnoreCase(body)?new java.util.Date(
System.currentTimeMillis()).toString():"BAD ORDER";
System.out.println(currentTime);
doWrite(sc,currentTime);
} else if(readBytes<0){ 

key.cancel();
sc.close();
}else { 

;
}
}
}
}
private void doWrite(SocketChannel sc, String response) throws IOException { 

if (response != null && response.trim().length()>0) { 

byte[] bytes = response.getBytes();
ByteBuffer writeBuffer =  ByteBuffer.allocate(bytes.length);
writeBuffer.put(bytes);
writeBuffer.flip();
sc.write(writeBuffer);
}
}
}

NioTimeClient ：

package com.jad.nettyArticle.nio;
public class NioTimeClient { 

public static void main(String[] args) { 

int port = 8080;
if (args!=null && args.length>0) { 

try { 

port = Integer.valueOf(args[0]);
} catch (NumberFormatException e) { 

e.printStackTrace();
}
}
new Thread(new TimeClientHandler("127.0.0.1",port),"TimeClient-001").start();
}
}

TimeClientHandler：

package com.jad.nettyArticle.nio;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;
public class TimeClientHandler implements Runnable { 

private String host;
private int port;
private Selector selector;
private SocketChannel socketChannel;
private volatile boolean stop = false;
public TimeClientHandler(String ip,int port) { 

this.host = ip ==null?"127.0.0.1":ip;
this.port = port;
try { 

selector=Selector.open();
socketChannel = SocketChannel.open();
socketChannel.configureBlocking(false);
System.out.println("Open the time channel succeed ,host :"+host+",port :"+port);
} catch (IOException e) { 

e.printStackTrace();
System.exit(1);
}
}
public void run() { 

try { 

System.out.println("Connnet the time server start!");
doConnect();
System.out.println("Connnet the time server end!");
} catch (Exception e) { 

e.printStackTrace();
System.exit(1);
}
while (!stop) { 

try { 

System.out.println("The client thread is running");
selector.select(1000);
Set<SelectionKey> selectionKeys = selector.selectedKeys();
Iterator<SelectionKey> it = selectionKeys.iterator();
System.out.println("The keys is :"+it);
SelectionKey key = null;
while (it.hasNext()) { 

key=it.next();
it.remove();
try { 

System.out.println("handle key is :"+key+" start");
handleInput(key);
System.out.println("handle key is :"+key+" end");
} catch (Exception e) { 

if (key != null) { 

key.cancel();
if (key.channel() != null) { 

key.channel().close();
}
}
e.printStackTrace();
}
}
} catch (IOException e) { 

e.printStackTrace();
System.exit(1);
}
}
if (selector != null) { 

try { 

selector.close();
} catch (IOException e) { 

e.printStackTrace();
}
}
}
private void doConnect() throws IOException { 

System.out.println("Connnet the time server!");
if (socketChannel.connect(new InetSocketAddress(host,port))) { 

socketChannel.register(selector,SelectionKey.OP_READ);
doWrite(socketChannel);
System.out.println("channel related to server register read operation!");
} else { 

socketChannel.register(selector,SelectionKey.OP_CONNECT);
System.out.println("channel related to server register connect operation!");
}
}
private void handleInput(SelectionKey key) throws IOException { 

System.out.println("handling key is :"+key+" start");
if (key.isValid()) { 

System.out.println("key :"+key+" valided");
SocketChannel sc = (SocketChannel)key.channel();
if (key.isConnectable()) { 

if (sc.finishConnect()) { 

System.out.println("key :"+key+" be Connected");
sc.register(selector,SelectionKey.OP_READ);
System.out.println("channel related to key :"+key+" register read operation!");
doWrite(sc);
System.out.println("channel related to key :"+key+" execute write action and send request!");
} else { 

System.exit(1);
}
}
if (key.isReadable()) { 

System.out.println("key :"+key+" can be read !");
//SocketChannel sc = (SocketChannel)key.channel();
ByteBuffer readBuffer = ByteBuffer.allocate(1024);
int readBytes = sc.read(readBuffer);
System.out.println("channel related to key :"+key+" length is "+readBytes);
if (readBytes>0) { 

readBuffer.flip();
byte[] bytes = new byte[readBuffer.remaining()];
readBuffer.get(bytes);
String body = new String(bytes,"UTF-8");
System.out.println("Now is :"+body);
this.stop=true;
} else if(readBytes<0){ 

key.cancel();
sc.close();
}else { 

;
}
}
}
}
private void doWrite(SocketChannel sc) throws IOException { 

byte[] bytes = "QUERY TIME ORDER".getBytes();
ByteBuffer writeBuffer =  ByteBuffer.allocate(bytes.length);
writeBuffer.put(bytes);
writeBuffer.flip();
sc.write(writeBuffer);
if (!writeBuffer.hasRemaining()) { 

System.out.println("Send order 2 server succeed.");
}
}
}

AioTimeServer：

package com.jad.nettyArticle.aio;
public class AioTimeServer { 

public static void main(String[] args) { 

int port=8080;
if(args!=null && args.length>0) { 

try { 

port = Integer.valueOf(args[0]);
} catch (NumberFormatException e) { 

e.printStackTrace();
}
}
AysncTimeServerHandler timeServer=new AysncTimeServerHandler(port);
new Thread(timeServer,"AIO-AysncTimeServerHandler-001").start();
}
}

AysncTimeServerHandler：

package com.jad.nettyArticle.aio;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.channels.AsynchronousServerSocketChannel;
import java.util.concurrent.CountDownLatch;
public class AysncTimeServerHandler implements Runnable{ 

private int port;
public CountDownLatch latch;
public AsynchronousServerSocketChannel asynchronousServerSocketChannel;
public AysncTimeServerHandler(int port) { 

this.port=port;
try { 

asynchronousServerSocketChannel=AsynchronousServerSocketChannel.open();
asynchronousServerSocketChannel.bind(new InetSocketAddress(port));
System.out.println("The time server is start in port :"+port);
} catch (IOException e) { 

e.printStackTrace();
}
}
public void run() { 

latch=new CountDownLatch(1);
doAccept();
try { 

latch.await();
} catch (InterruptedException e) { 

e.printStackTrace();
}
}
private void doAccept() { 

asynchronousServerSocketChannel.accept(this,new AcceptCompletionHandler());
}
}

AcceptCompletionHandler ：

package com.jad.nettyArticle.aio;
import java.nio.ByteBuffer;
import java.nio.channels.AsynchronousSocketChannel;
public class AcceptCompletionHandler implements java.nio.channels.CompletionHandler<java.nio.channels.AsynchronousSocketChannel,  AysncTimeServerHandler> { 

@Override
public void completed(AsynchronousSocketChannel result, AysncTimeServerHandler attachment) { 

attachment.asynchronousServerSocketChannel.accept(attachment,this);
ByteBuffer buffer=ByteBuffer.allocate(1024);
result.read(buffer,buffer,new ReadCompletionHandler(result));
}
@Override
public void failed(Throwable exc, AysncTimeServerHandler attachment) { 

exc.printStackTrace();
attachment.latch.countDown();
}
}

ReadCompletionHandler：

package com.jad.nettyArticle.aio;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import java.nio.channels.AsynchronousSocketChannel;
import java.nio.channels.CompletionHandler;
public class ReadCompletionHandler implements CompletionHandler<Integer, ByteBuffer> { 

private  AsynchronousSocketChannel channel;
public ReadCompletionHandler(AsynchronousSocketChannel result) { 

if (this.channel==null) { 

this.channel=result;
}
}
@Override
public void completed(Integer result, ByteBuffer attachment) { 

attachment.flip();
byte[] body=new byte[attachment.remaining()];
attachment.get(body);
try { 

String req = new String(body,"UTF-8");
System.out.println("The time server receive order :"+req);
String currentTime="QUERY TIME ORDER".equalsIgnoreCase(req)?new java.util.Date(
System.currentTimeMillis()).toString():"BAD ORDER";
System.out.println(currentTime);
doWrite(currentTime);
} catch (UnsupportedEncodingException e) { 

e.printStackTrace();
}
}
private void doWrite(String currentTime) { 

if (currentTime != null && currentTime.trim().length()>0) { 

byte[] bytes=currentTime.getBytes();
ByteBuffer writeBuffer =  ByteBuffer.allocate(bytes.length);
writeBuffer.put(bytes);
writeBuffer.flip();
channel.write(writeBuffer, writeBuffer, new CompletionHandler<Integer, ByteBuffer>() { 

@Override
public void completed(Integer result, ByteBuffer attachment) { 

if (attachment.hasRemaining()) { 

channel.write(attachment,attachment,this);
}
}
@Override
public void failed(Throwable exc, ByteBuffer attachment) { 

try { 

channel.close();
} catch (IOException e) { 

e.printStackTrace();
}
}
});
}
}
@Override
public void failed(Throwable exc, ByteBuffer attachment) { 

try { 

this.channel.close();
} catch (IOException e) { 

e.printStackTrace();
}
}
}

AioTimeClient：

package com.jad.nettyArticle.aio;
public class AioTimeClient { 

public static void main(String[] args) { 

int port = 8080;
if (args!=null && args.length>0) { 

try { 

port = Integer.valueOf(args[0]);
} catch (NumberFormatException e) { 

e.printStackTrace();
}
}
new Thread(new AsyncTimeClientHandler("127.0.0.1",port),"AIO-AsyncTimeClientHandler-001").start();
}
}

AsyncTimeClientHandler：

package com.jad.nettyArticle.aio;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.AsynchronousSocketChannel;
import java.nio.channels.CompletionHandler;
import java.util.concurrent.CountDownLatch;
public class AsyncTimeClientHandler implements CompletionHandler<Void, AsyncTimeClientHandler>,Runnable { 

private AsynchronousSocketChannel client;
private String host;
private int port;
private CountDownLatch latch;
public AsyncTimeClientHandler(String s, int port) { 

this.host=s;
this.port=port;
try { 

client=AsynchronousSocketChannel.open();
} catch (IOException e) { 

e.printStackTrace();
}
}
@Override
public void run() { 

latch=new CountDownLatch(1);
client.connect(new InetSocketAddress(host,port),this,this);
try { 

latch.await();
} catch (InterruptedException e) { 

e.printStackTrace();
}
try { 

client.close();
} catch (IOException e) { 

e.printStackTrace();
}
}
@Override
public void completed(Void result, AsyncTimeClientHandler attachment) { 

byte[] bytes = "QUERY TIME ORDER".getBytes();
ByteBuffer writeBuffer =  ByteBuffer.allocate(bytes.length);
writeBuffer.put(bytes);
writeBuffer.flip();
client.write(writeBuffer, writeBuffer, new CompletionHandler<Integer, ByteBuffer>() { 

@Override
public void completed(Integer result, ByteBuffer attachment) { 

if (attachment.hasRemaining()) { 

client.write(attachment,attachment,this);
} else { 

ByteBuffer readbuffer=ByteBuffer.allocate(1024);
client.read(readbuffer, readbuffer, new CompletionHandler<Integer, ByteBuffer>() { 

@Override
public void completed(Integer result, ByteBuffer attachment) { 

attachment.flip();
byte[] bytes = new byte[attachment.remaining()];
attachment.get(bytes);
try { 

String body = new String(bytes,"UTF-8");
System.out.println("Now is :"+body);
latch.countDown();
} catch (UnsupportedEncodingException e) { 

e.printStackTrace();
}
}
@Override
public void failed(Throwable exc, ByteBuffer attachment) { 

try { 

client.close();
latch.countDown();
} catch (IOException e) { 

e.printStackTrace();
}
}
});
}
}
@Override
public void failed(Throwable exc, ByteBuffer attachment) { 

try { 

client.close();
latch.countDown();
} catch (IOException e) { 

e.printStackTrace();
}
}
});
}
@Override
public void failed(Throwable exc, AsyncTimeClientHandler attachment) { 

exc.printStackTrace();
try { 

client.close();
latch.countDown();
} catch (IOException e) { 

e.printStackTrace();
}
}
}

NettyTimeServer：

package com.jad.nettyArticle.netty;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
public class NettyTimeServer { 

public static void main(String[] args) throws Exception { 

int port = 8080;
if (args!=null && args.length>0) { 

try { 

port = Integer.valueOf(args[0]);
} catch (NumberFormatException e) { 

e.printStackTrace();
}
}
new NettyTimeServer().bind(port);
}
private void bind(int port) throws Exception { 

EventLoopGroup bossGroup=new NioEventLoopGroup();
EventLoopGroup workerGroup=new NioEventLoopGroup();
try { 

ServerBootstrap b=new ServerBootstrap();
b.group(bossGroup,workerGroup).channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG,1024)
.childHandler(new ChildChannelHandler());
ChannelFuture f=b.bind(port).sync();
f.channel().closeFuture().sync();
} finally { 

bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
private class ChildChannelHandler extends ChannelInitializer<SocketChannel> { 

@Override
protected void initChannel(SocketChannel socketChannel) throws Exception { 

socketChannel.pipeline().addLast(new NettyTimeServerHandler());
}
}
}

NettyTimeServerHandler：

package com.jad.nettyArticle.netty;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
public class NettyTimeServerHandler extends ChannelHandlerAdapter { 

@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { 

ByteBuf buf=(ByteBuf)msg;
byte[] req = new byte[buf.readableBytes()];
buf.readBytes(req);
String body=new String(req,"UTF-8");
System.out.println("The time server receive order :"+body);
String currentTime="QUERY TIME ORDER".equalsIgnoreCase(body)?new java.util.Date(
System.currentTimeMillis()).toString():"BAD ORDER";
ByteBuf resp = Unpooled.copiedBuffer(currentTime.getBytes());
ctx.write(resp);
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception { 

ctx.flush();
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { 

ctx.close();
}
}

NettyTimeClient：

package com.jad.nettyArticle.netty;
import com.jad.nettyArticle.nio.TimeClientHandler;
import io.netty.bootstrap.Bootstrap;
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;
public class NettyTimeClient { 

public static void main(String[] args) throws InterruptedException { 

int port = 8080;
if (args!=null && args.length>0) { 

try { 

port = Integer.valueOf(args[0]);
} catch (NumberFormatException e) { 

e.printStackTrace();
}
}
new NettyTimeClient().connect(port,"127.0.0.1");
}
private void connect(int port, String s) throws InterruptedException { 

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
protected void initChannel(SocketChannel socketChannel) throws Exception { 

socketChannel.pipeline().addLast(new NettyTimeClientHandler());
}
});
ChannelFuture f=b.connect(s,port).sync();
f.channel().closeFuture().sync();
} finally { 

group.shutdownGracefully();
}
}
}

NettyTimeClientHandler：

package com.jad.nettyArticle.netty;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import java.util.logging.Logger;
public class NettyTimeClientHandler extends ChannelHandlerAdapter { 

private static final Logger logger = Logger.getLogger(NettyTimeClientHandler.class.getName());
private final ByteBuf  firstMessage;
public NettyTimeClientHandler() { 

byte[] bytes="QUERY TIME ORDER".getBytes();
this.firstMessage = Unpooled.buffer(bytes.length);
this.firstMessage.writeBytes(bytes);
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception { 

ctx.writeAndFlush(firstMessage);
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { 

ByteBuf buf=(ByteBuf)msg;
byte[] req = new byte[buf.readableBytes()];
buf.readBytes(req);
String body=new String(req,"UTF-8");
System.out.println("Now is :"+body);
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { 

logger.warning("Unexpected exception from downstream :"+cause.getMessage());
ctx.close();
}
}

参考资料：
https://blog.csdn.net/m0_38125278/article/details/85610025
https://blog.csdn.net/g1l2y3/article/details/53114765
https://blog.csdn.net/wireless_com/article/details/45935591
https://blog.csdn.net/buyueliuying/article/details/53572066
https://blog.csdn.net/qq_34781336/article/details/84834801