Netty入门案例

<?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>org.example</groupId>
    <artifactId>NettyIntroduction</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>

    <dependencies>
        <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>4.1.8.Final</version>
        </dependency>
    </dependencies>

    <!--maven编译插件-->
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.2</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <showWarnings>true</showWarnings>
                </configuration>
            </plugin>
        </plugins>
    </build>
     


</project>

package cn.cmdzz.netty.introduction;

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

/**
 * 处理服务器端的业务
 *
 */
//找到父类方法快捷键：ctrl+o
public class NettyServerHandler extends ChannelInboundHandlerAdapter {

    /**
     * 读取数据事件
     * @param ctx
     * @param msg 消息
     * @throws Exception
     */
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        System.out.println("Server ctx:"+ctx);
        ByteBuf buf = (ByteBuf) msg;
        System.out.println("客户端发来的消息："+buf.toString(CharsetUtil.UTF_8));
    }

    /**
     * 数据读取完毕事件
     * @param ctx
     * @throws Exception
     */
    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        //创建一个缓冲区写入字符串返回 Unpooled.copiedBuffer("我是服务器端",CharsetUtil.UTF_8)
        ctx.writeAndFlush(Unpooled.copiedBuffer("我是服务器端",CharsetUtil.UTF_8));
    }

    /**
     * 异常发生事件
     * @param ctx
     * @param t
     * @throws Exception
     */
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable t) throws Exception {
       //异常发生时关闭一下
        ctx.close();
    }
}

package cn.cmdzz.netty.introduction;

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

/**
 * 服务器端
 */
public class NettyServer {
    public static void main(String[] args) throws Exception{

        //1.创建一个线程数组，接受客户端连接
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        //2.创建一个线程数组，处理网络操作
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        //3.创建服务器端启动助手来配置参数
        ServerBootstrap bootstrap = new ServerBootstrap();
        bootstrap.group(bossGroup,workerGroup)//设置两个线程数组
        .channel(NioServerSocketChannel.class)//使用NioServerSocketChannel作为服务器端通道的实现
        .option(ChannelOption.SO_BACKLOG,128)//设置线程队列中等待连接的个数
        .childOption(ChannelOption.SO_KEEPALIVE,true)//保持活动连接状态
        .childHandler(new ChannelInitializer<SocketChannel>() {

            @Override
            protected void initChannel(SocketChannel socketChannel) throws Exception {//初始化通道
                socketChannel.pipeline().addLast(new NettyServerHandler());//把自定义Handler加入管道
            }
        });

        System.out.println("........Server is ready...........");

        ChannelFuture cf = bootstrap.bind(9999).sync();//绑定端口 非阻塞
        System.out.println("......Server is starting..........");

        //关闭通道 关闭线程组
        cf.channel().closeFuture().sync();//异步
        bossGroup.shutdownGracefully();
        workerGroup.shutdownGracefully();
    }
}

package cn.cmdzz.netty.introduction;

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

/**
 * 处理客户端业务
 */
public class NettyClientHandler extends ChannelInboundHandlerAdapter {


    //通道就绪事件
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("Client ctx:"+ctx);
        ctx.writeAndFlush(Unpooled.copiedBuffer("服务器，我是客户端", CharsetUtil.UTF_8));
    }



    //读服务器返回的数据
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        ByteBuf buf = (ByteBuf) msg;
        System.out.println("服务器端发来的消息："+buf.toString(CharsetUtil.UTF_8));
    }
}

package cn.cmdzz.netty.introduction;

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;

/**
 * 客户端
 */
public class NettyClient {
    public static void main(String[] args) throws Exception{
        //创建一个线程组
        EventLoopGroup group = new NioEventLoopGroup();
        //创建客户端的启动助手，完成相关配置
        Bootstrap bootstrap = new Bootstrap();

        bootstrap.group(group)  //设置线程组
        .channel(NioSocketChannel.class)//设置客户端通道的实现类
        .handler(new ChannelInitializer<SocketChannel>() {

            @Override
            protected void initChannel(SocketChannel socketChannel) throws Exception {
                socketChannel.pipeline().addLast(new NettyClientHandler());//往Pipeline链中添加自定义的handler
            }
        });

        System.out.println("......client ready......");
        //启动客户端连接服务器
        ChannelFuture cf = bootstrap.connect("127.0.0.1",9999).sync();
        System.out.println(".........client starting.....");

        //关闭连接
        cf.channel().closeFuture().sync();

    }
}