netty是由jboss提供的一个java开源框架。netty提供异步的、事件驱动的网络应用程序框架和工具，用以快速开发高性能、高可靠性的网络服务器和客户端程序。
也就是说，netty 是一个基于nio的客户、服务器端编程框架，使用netty 可以确保你快速和简单的开发出一个网络应用，例如实现了某种协议的客户、服务端应用。netty相当于简化和流线化了网络应用的编程开发过程，例如：基于tcp和udp的socket服务开发。
“快速”和“简单”并不用产生维护性或性能上的问题。netty 是一个吸收了多种协议（包括ftp、smtp、http等各种二进制文本协议）的实现经验，并经过相当精心设计的项目。最终，netty 成功的找到了一种方式，在保证易于开发的同时还保证了其应用的性能，稳定性和伸缩性。
netty is an asynchronous event-driven network application framework
for rapid development of maintainable high performance protocol servers & clients.
客户端向服务器发送hellonetty-server!服务器向客户端返回hello netty-client!
服务端channelhandler
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package com.xm.netty;
import io.netty.buffer.bytebuf;
import io.netty.buffer.unpooled;
import io.netty.channel.channelfuturelistener;
import io.netty.channel.channelhandlercontext;
import io.netty.channel.channelinboundhandleradapter;
import io.netty.util.charsetutil;
public class serverhandler extends channelinboundhandleradapter {
@override
public void channelread(channelhandlercontext ctx, object msg) throws exception {
bytebuf in = (bytebuf) msg;
system.out.println("服务器接收："+in.tostring(charsetutil.utf_8));
in.clear();
string str = "hello netty-client!";
in.writebytes(str.getbytes());
ctx.write(in);
}
@override
public void channelreadcomplete(channelhandlercontext ctx) throws exception {
ctx.writeandflush(unpooled.empty_buffer).addlistener(channelfuturelistener.close);
}
@override
public void exceptioncaught(channelhandlercontext ctx, throwable cause) throws exception {
cause.printstacktrace();
ctx.close();
}
}
服务端server
package com.xm.netty;
import java.net.inetsocketaddress;
import io.netty.bootstrap.serverbootstrap;
import io.netty.channel.channel;
import io.netty.channel.channelfuture;
import io.netty.channel.channelinitializer;
import io.netty.channel.eventloopgroup;
import io.netty.channel.nio.nioeventloopgroup;
import io.netty.channel.socket.nio.nioserversocketchannel;
public class server {
private final int port;
public server(int port) {
this.port = port;
}
public static void main(string[] args) {
int port = 8989;
try {
new server(port).start();
} catch (interruptedexception e) {
// todo auto-generated catch block
e.printstacktrace();
}
}
private void start() throws interruptedexception {
final serverhandler serverhandler = new serverhandler();
eventloopgroup group = new nioeventloopgroup();
try {
serverbootstrap bootstrap = new serverbootstrap();
bootstrap
.group(group)
.channel(nioserversocketchannel.class)
.localaddress(new inetsocketaddress( port))
.childhandler(new channelinitializer() {
@override
protected void initchannel(channel ch) throws exception {
ch.pipeline().addlast(serverhandler);
}
});
channelfuture future = bootstrap.bind().sync();
future.channel().closefuture().sync();
} finally {
group.shutdowngracefully().sync();
}
}
}
客户端channelhandler
package com.xm.netty;
import io.netty.buffer.bytebuf;
import io.netty.buffer.unpooled;
import io.netty.channel.channelhandlercontext;
import io.netty.channel.simplechannelinboundhandler;
import io.netty.util.charsetutil;
public class clienthandler extends simplechannelinboundhandler<bytebuf> {
@override
public void channelactive(channelhandlercontext ctx) throws exception {
ctx.writeandflush(unpooled.copiedbuffer("hello netty-server!",charsetutil.utf_8));
}
@override
protected void channelread0(channelhandlercontext ctx, bytebuf msg) throws exception {
system.out.println("客户端接收到消息："+msg.tostring(charsetutil.utf_8));
}
@override
public void exceptioncaught(channelhandlercontext ctx, throwable cause) throws exception {
cause.printstacktrace();
ctx.close();
}
}
客户端client
package com.xm.netty;
import io.netty.bootstrap.bootstrap;
import io.netty.channel.channelfuture;
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.niosocketchannel;
public class client {
private final int port;
private final string host;
public client(int port, string host) {
this.port = port;
this.host = host;
}
public static void main(string[] args) {
string host = "127.0.0.1";
int port = 8989;
try {
new client(port, host).start();
} catch (interruptedexception e) {
// todo auto-generated catch block
e.printstacktrace();
}
}
private void start() throws interruptedexception {
eventloopgroup group = new nioeventloopgroup();
try {
bootstrap bootstrap = new bootstrap();
bootstrap
.group(group)
.channel(niosocketchannel.class)
.remoteaddress(host, port)
.handler(new channelinitializer<socketchannel>() {
@override
protected void initchannel(socketchannel ch) throws exception {
ch.pipeline().addlast(new clienthandler());
}
});
channelfuture future = bootstrap.connect().sync();
future.channel().closefuture().sync();
} finally {
group.shutdowngracefully().sync();
}
}
}
导入依赖
<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.xm</groupid>
<artifactid>netty</artifactid>
<version>0.0.1-snapshot</version>
<dependencies>
<dependency>
<groupid>io.netty</groupid>
<artifactid>netty-all</artifactid>
<version>4.1.16.final</version>
</dependency>
</dependencies>
</project>服务端：
服务器接收：hello netty-server!
客户端：
客户端接收到消息：hello netty-client!
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