Netty入门
1.Netty介绍
（1）百度百科介绍：
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。
（2）官网介绍：netty.io
Netty is an asynchronous event-driven network application framework
for rapid development of maintainable high performance protocol servers & clients.
（3）参考资料：
参考书籍：Netty实战（Norman Maurer & Marvin Allen Wolfthal）
参考官方文档：https://netty.io/wiki/user-guide.html
参考网址：https://ifeve.com/tag/netty/
2.程序功能概述
客户端向服务器发送HelloNetty-Server!服务器向客户端返回Hello Netty-Client!
3.程序实现
服务端ChannelHandler
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
{
@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() {
@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
4.0.0
com.xm
netty
0.0.1-SNAPSHOT
io.netty
netty-all
4.1.16.Final
4.运行结果：
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!https://www.cnblogs.com/TimerHotel/p/netty01.html
