nio使用之netty框架

最新推荐文章于 2024-01-05 09:25:13 发布

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最新推荐文章于 2024-01-05 09:25:13 发布

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本文介绍了一个简单的Netty服务端与客户端通信示例，包括如何配置服务端和客户端，实现基本的消息收发功能。通过创建HelloServer及HelloClient两个类，并设置相应的初始化器和处理器来完成通信流程。

1.官网上下载相应的jar包http://netty.io/downloads.html

当然，使用maven更方便，直接添加相应的依赖就行

2.创建工程，将下载好的包导入进去

这个是我的目录结构

服务器端：

1.创建HelloServer

package kang.server;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;

public class HelloServer {
	 /**
     * 服务端监听的端口地址
     */
    private static final int portNumber = 7878;
    
    public static void main(String[] args) throws InterruptedException {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup);
            b.channel(NioServerSocketChannel.class);
            b.childHandler(new HelloServerInitializer());

            // 服务器绑定端口监听
            ChannelFuture f = b.bind(portNumber).sync();
            // 监听服务器关闭监听
            f.channel().closeFuture().sync();

            // 可以简写为
            /* b.bind(portNumber).sync().channel().closeFuture().sync(); */
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

2.创建HelloServerInitializer

package kang.server;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.Delimiters;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;

public class HelloServerInitializer extends ChannelInitializer<SocketChannel> {

	@Override
	protected void initChannel(SocketChannel ch) throws Exception {
		ChannelPipeline pipeline = ch.pipeline();

		// 以("\n")为结尾分割的 解码器
		pipeline.addLast("framer", new DelimiterBasedFrameDecoder(8192, Delimiters.lineDelimiter()));

		// 字符串解码 和 编码
		pipeline.addLast("decoder", new StringDecoder());
		pipeline.addLast("encoder", new StringEncoder());

		// 自己的逻辑Handler
		pipeline.addLast("handler", new HelloServerHandler());
	}
}

3.创建HelloServerHandler

package kang.server;

import java.net.InetAddress;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;

public class HelloServerHandler extends SimpleChannelInboundHandler<String> {

	@Override
	protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
		// 收到消息直接打印输出
		System.out.println(ctx.channel().remoteAddress() + " Say : " + msg);

		// 返回客户端消息 - 我已经接收到了你的消息
		ctx.writeAndFlush("Received your message !\n");
	}

	/*
	 * 
	 * 覆盖 channelActive 方法 在channel被启用的时候触发 (在建立连接的时候)
	 * 
	 * channelActive 和 channelInActive 在后面的内容中讲述，这里先不做详细的描述
	 * */
	@Override
	public void channelActive(ChannelHandlerContext ctx) throws Exception {

		System.out.println("RamoteAddress : " + ctx.channel().remoteAddress() + " active !");

		ctx.writeAndFlush( "Welcome to " + InetAddress.getLocalHost().getHostName() + " service!\n");

		super.channelActive(ctx);
	}
}

客户端：

1.创建HelloClient

package kang.client;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

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

public class HelloClient {
	public static String host = "127.0.0.1";
	public static int port = 7878;

	/**
	 * @param args
	 * @throws InterruptedException 
	 * @throws IOException 
	 */
	public static void main(String[] args) throws InterruptedException, IOException {
		EventLoopGroup group = new NioEventLoopGroup();
		try {
			Bootstrap b = new Bootstrap();
			b.group(group)
			.channel(NioSocketChannel.class)
			.handler(new HelloClientInitializer());

			// 连接服务端
			Channel ch = b.connect(host, port).sync().channel();

			// 控制台输入
			BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
			for (;;) {
				String line = in.readLine();
				if (line == null||line.trim().equalsIgnoreCase("over")) {
					break;
				}
				/*
				 * 向服务端发送在控制台输入的文本 并用"\r\n"结尾
				 * 之所以用\r\n结尾 是因为我们在handler中添加了 DelimiterBasedFrameDecoder 帧解码。
				 * 这个解码器是一个根据\n符号位分隔符的解码器。所以每条消息的最后必须加上\n否则无法识别和解码
				 * */
				ch.writeAndFlush(line + "\r\n");
			}
		} finally {
			// The connection is closed automatically on shutdown.
			group.shutdownGracefully();
		}
	}
}

2.创建HelloClientInitializer

package kang.client;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.Delimiters;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;

public class HelloClientInitializer extends ChannelInitializer<SocketChannel> {
	

	@Override
	protected void initChannel(SocketChannel ch) throws Exception {
		ChannelPipeline pipeline = ch.pipeline();

		/*
		 * 这个地方的 必须和服务端对应上。否则无法正常解码和编码
		 * 
		 * 解码和编码 我将会在下一张为大家详细的讲解。再次暂时不做详细的描述
		 * 
		 * */
		pipeline.addLast("framer", new DelimiterBasedFrameDecoder(8192, Delimiters.lineDelimiter()));
		pipeline.addLast("decoder", new StringDecoder());
		pipeline.addLast("encoder", new StringEncoder());

		// 客户端的逻辑
		pipeline.addLast("handler", new HelloClientHandler());
	}
}

3.创建HelloClientHandler

package kang.client;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;

public class HelloClientHandler extends SimpleChannelInboundHandler<String> {

	@Override
	protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {

		System.out.println("Server say : " + msg);
	}

	@Override
	public void channelActive(ChannelHandlerContext ctx) throws Exception {
		System.out.println("Client active ");
		super.channelActive(ctx);
	}

	@Override
	public void channelInactive(ChannelHandlerContext ctx) throws Exception {
		System.out.println("Client close ");
		super.channelInactive(ctx);
	}
}

代码写好后，测试

客户端：

服务端：