第一个Netty程序

netty就是一个高性能的NIO框架,用于java网络编程。下面说说思路:

服务端:

开启通道、设置网络通信方式、设置端口、设置接收请求的handler、绑定通道、最后关闭

客户端:

开启通道、设置网络通信方式、设置服务器ip和端口、设置处理数据的handler、连接服务器、最后关闭。

pom.xml引用如下:

<dependency>
    <groupId>io.netty</groupId>
    <artifactId>netty-all</artifactId>
    <version>4.1.28.Final</version>
</dependency>

服务端总共两个类,EchoServer.java和EchoServerHandler.java。

EchoServer.java

package cn.enjoyedu.ch02.echo;

import io.netty.bootstrap.ServerBootstrap;
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.NioServerSocketChannel;

import java.net.InetSocketAddress;

/** * 
 * 创建日期:2018/08/25
 * 类说明:
 */
public class EchoServer  {

    private final int port;

    public EchoServer(int port) {
        this.port = port;
    }

    public static void main(String[] args) throws InterruptedException {
        int port = 9999;
        EchoServer echoServer = new EchoServer(port);
        System.out.println("服务器即将启动");
        echoServer.start();
        System.out.println("服务器关闭");
    }

    public void start() throws InterruptedException {
        final EchoServerHandler serverHandler = new EchoServerHandler();
        /*线程组*/
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();/*服务端启动必备*/
            b.group(group)
                    /*指明使用NIO进行网络通讯*/
            .channel(NioServerSocketChannel.class)
                    /*指明服务器监听端口*/
                    .localAddress(new InetSocketAddress(port))
                    /*接收到连接请求,新启一个socket通信,也就是channel,每个channel
                    * 有自己的事件的handler*/
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ch.pipeline().addLast(new EchoServerHandler());
                        }
                    });
            ChannelFuture f = b.bind().sync();/*绑定到端口,阻塞等待直到连接完成*/
            /*阻塞,直到channel关闭*/
            f.channel().closeFuture().sync();
        } finally {
            group.shutdownGracefully().sync();
        }
    }


}
View Code

EchoServerHandler.java

package cn.enjoyedu.ch02.echo;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.util.CharsetUtil;

/**
 * 创建日期:2018/08/25
 * 类说明:自己的业务处理
 */
/*指明我这个handler可以在多个channel之间共享,意味这个实现必须线程安全的。*/
@ChannelHandler.Sharable
public class EchoServerHandler extends ChannelInboundHandlerAdapter {

    /*** 服务端读取到网络数据后的处理*/
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg)
            throws Exception {
        ByteBuf in = (ByteBuf)msg;/*netty实现的缓冲区*/
        System.out.println("Server Accept:"+in.toString(CharsetUtil.UTF_8));
        ctx.write(in);
    }

    /*** 服务端读取完成网络数据后的处理*/
    @Override
    public void channelReadComplete(ChannelHandlerContext ctx)
            throws Exception {
        ctx.writeAndFlush(Unpooled.EMPTY_BUFFER)/*flush掉所有的数据*/
                .addListener(ChannelFutureListener.CLOSE);/*当flush完成后,关闭连接*/
    }

    /*** 发生异常后的处理*/
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
            throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}
View Code

 

客户端总共两个类,EchoClient.java和EchoClientHandler.java

EchoClient.java

package cn.enjoyedu.ch02.echo;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;

import java.net.InetSocketAddress;

/**
 * 创建日期:2018/08/26
 * 类说明:netty的客户端
 */
public class EchoClient {

    private final int port;
    private final String host;

    public EchoClient(int port, String host) {
        this.port = port;
        this.host = host;
    }

    public void start() throws InterruptedException {
        EventLoopGroup group = new NioEventLoopGroup();/*线程组*/
        try {
            Bootstrap b = new Bootstrap();/*客户端启动必备*/
            b.group(group)
                .channel(NioSocketChannel.class)/*指明使用NIO进行网络通讯*/
                .remoteAddress(new InetSocketAddress(host,port))/*配置远程服务器的地址*/
                .handler(new EchoClientHandler());
            ChannelFuture f = b.connect().sync();/*连接到远程节点,阻塞等待直到连接完成*/
            /*阻塞,直到channel关闭*/
            f.channel().closeFuture().sync();
        } finally {
            group.shutdownGracefully().sync();
        }
    }

    public static void main(String[] args) throws InterruptedException {
        new EchoClient(9999,"127.0.0.1").start();
    }
}
View Code

EchoClientHandler.java

package cn.enjoyedu.ch02.echo;

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;

/**
 * 创建日期:2018/08/26
 * 类说明:
 */
public class EchoClientHandler extends SimpleChannelInboundHandler<ByteBuf> {

    /*客户端读取到数据后干什么*/
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, ByteBuf msg)
            throws Exception {
        System.out.println("Client accetp:"+msg.toString(CharsetUtil.UTF_8));
    }

    /*客户端被通知channel活跃以后,做事*/
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        //往服务器写数据
        ctx.writeAndFlush(Unpooled.copiedBuffer("Hello,Netty",
                CharsetUtil.UTF_8));
    }

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

}
View Code

 

代码里面也有具体的注释。

 

posted @ 2018-10-11 16:46  段江涛IT  阅读(338)  评论(0编辑  收藏  举报
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