Go Netty Getting Started (the simplest Netty client/server program)

NiO in Java is a basic technique for solving blocking IO problems, but the preparation of NIO is a high requirement for Java programmers. Then Netty is a sophisticated network IO programming framework for simplifying operations. Here is a brief introduction of a program, the code is "Netty in action" inside, but the inside of the example is a bit of a problem, anyway I did not run successfully, modified after success. Directly on the code:

First, the server writing

Server code, listening for connections

 1 package com.gerry.netty.server; 2 3 Import Io.netty.bootstrap.ServerBootstrap; 4 Import io.netty.channel.ChannelFuture; 5 Import Io.netty.channel.ChannelInitializer; 6 Import Io.netty.channel.EventLoopGroup; 7 Import Io.netty.channel.nio.NioEventLoopGroup; 8 Import Io.netty.channel.socket.SocketChannel; 9 Import io.netty.channel.socket.nio.nioserversocketchannel;10 One public class Echoserver {$ private final int port;1 3 public echoserver (int port) {This.port = port;16}17-public void Start () throws Exception { Eventloopgroup Group = new Nioeventloopgroup (); try {serverbootstrap sb = new Serverbo Otstrap (); Sb.group (group)//Binding thread pool (nioserversocketchannel.class)//specified using Cha Nnel24. LocalAddress (This.port)//binding listening port. Childhandler (New Channelinitializer&lt ; Socketchannel> () {//BIND client connection when trigger action @OveRride28 protected void Initchannel (Socketchannel ch) throws Exception {29 System.out.println ("Connected ...; Client: "+ ch.remoteaddress ()); Ch.pipeline (). AddLast (New Echoserverhandler ()); Client trigger Operation}32}); Channelfuture CF = Sb.bind ( ). sync (); The server asynchronously creates bindings System.out.println (Echoserver.class + "started and listen on" + Cf.channel (). localaddress ()); Cf.channel (). Closefuture (). sync ();     Close server Channel--finally {PNS group.shutdowngracefully (). sync ();//Release thread pool resource 38}39}40 41 public static void Main (string[] args) throws Exception {new Echoserver (65535). Start ();//Start 43}44}

Specific code to handle the client connection

 1 package com.gerry.netty.server; 2 3 Import io.netty.buffer.Unpooled; 4 Import Io.netty.channel.ChannelFutureListener; 5 Import Io.netty.channel.ChannelHandlerContext; 6 Import Io.netty.channel.ChannelInboundHandlerAdapter; 7 8 public class Echoserverhandler extends Channelinboundhandleradapter {9 @Override10 public void Channelread (C Hannelhandlercontext ctx, Object msg) throws Exception {one System.out.println ("Server channelread ...; Received: "+ msg"), Ctx.write (msg),}14 @Override16 public void Channelreadcomplete (Channelhandl Ercontext ctx) throws Exception {System.out.println ("Server Channelreadcomplete.."); 18//The first method: Write an empty buf and refresh the write area. Close the sock channel connection when finished. Ctx.writeandflush (Unpooled.empty_buffer). AddListener (Channelfuturelistener.close);//ctx.flush (); The second method: Close the channel connection on the client side, so that the two-Channelreadcomplete method is triggered. //ctx.flush (). Close (). sync (); The Third Kind: change to this kind of writing also can, but this writing, there is no first method of good. 22}23 24 @Override25 public void Exceptioncaught (Channelhandlercontext ctx, Throwable cause) throws Exception {26 SYSTEM.OUT.PRINTLN ("Server occur exception:" + Cause.getmessage ()); Cause.printstacktrace (); Ctx.clos E (); Closes the connection where the exception occurred 29}30}

Second, the client writing

The specific connection code

 1 package com.gerry.netty.client; 2 3 Import Io.netty.bootstrap.Bootstrap; 4 Import io.netty.channel.ChannelFuture; 5 Import Io.netty.channel.ChannelInitializer; 6 Import Io.netty.channel.EventLoopGroup; 7 Import Io.netty.channel.nio.NioEventLoopGroup; 8 Import Io.netty.channel.socket.SocketChannel; 9 Import io.netty.channel.socket.nio.niosocketchannel;10 Import java.net.inetsocketaddress;12 public class Echoclient {+ Private final String host;15 private final int port;16-public echoclient () {( 0);}20 public echoclient (int port) {("localhost", port),}24. Public Echoclient (S Tring host, int port) {This.host = host;27 This.port = port;28}29 public void start () throw s Exception {eventloopgroup group = new Nioeventloopgroup (); try {Bootstrap b = new Bo Otstrap (); B.group (group)//Registration thread pool (niosocketchannel. Class)//use Niosocketchannel as the channel class for the connection. Remoteaddress (New Inetsocketaddress (This.host, This.po                                 RT)//BIND connection port and host information. Handler (new channelinitializer<socketchannel> () {//bind connection initializer 38 @Override39 protected void Initchannel (Socketchannel ch) throws E                                     xception {System.out.println ("connected ..."); 41             Ch.pipeline (). AddLast (New Echoclienthandler ()); 42}43}); 44 System.out.println ("created."); Channelfuture CF = B.connect (). sync (); Asynchronous Connection Server System.out.println ("Connected ..."); Connection completed by Cf.channel (). Closefuture (). sync (); Asynchronously waits to close the connection channel50 System.out.println ("closed."); Close Finish} finally {group.shutdowngracefully (). sync ();//Release thread pool resource 53}54    }55-public static void main (string[] args) throws Exception {new echoclient ("127.0.0.1", 65535). Star T (); Connect 127.0.0.1/65535, and start 58}59}

After the connection is successful, the specific communication code

 1 package com.gerry.netty.client; 2 3 Import Java.nio.charset.Charset; 4 5 Import Io.netty.buffer.ByteBuf; 6 Import Io.netty.buffer.ByteBufUtil; 7 Import io.netty.buffer.Unpooled; 8 Import Io.netty.channel.ChannelHandlerContext; 9 Import io.netty.channel.simplechannelinboundhandler;10 Import io.netty.util.charsetutil;11 public class Echoclienthandler extends simplechannelinboundhandler<bytebuf> {@Override15 public void channelactive ( Channelhandlercontext ctx) throws Exception {System.out.println ("client channelactive.."); Ctx.writeandflush (Unpooled.copiedbuffer ("Netty rocks!", charsetutil.utf_8));         Must have flush18 19//must exist FLUSH20//Ctx.write (Unpooled.copiedbuffer ("Netty rocks!", Charsetutil.utf_8)); 21 Ctx.flush ();}23 @Override25 protected void channelRead0 (Channelhandlercontext ctx, Bytebuf ms g) throws Exception {System.out.println ("client channelread.."); Bytebuf buf = Msg.Readbytes (Msg.readablebytes ()); System.out.println ("Client Received:" + bytebufutil.hexdump (BUF) + ";     The value is: "+ buf.tostring (charset.forname (" Utf-8 "));//ctx.channel (). Close (). sync ();//client close channel Connection 30 }31 @Override33 public void Exceptioncaught (Channelhandlercontext ctx, Throwable cause) throws Exception {3 4 Cause.printstacktrace (); Ctx.close (); 36}37 38}

Iii. Results

Run server first, and then run the client.

Reprint Link: http://www.cnblogs.com/liuming1992/p/4758532.html

Version used by Netty above

<!--Https://mvnrepository.com/artifact/io.netty/netty-all--
<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
<version>4.1.6.Final</version>
</dependency>

Go Netty Getting Started (the simplest Netty client/server program)