java echo程序_Java Netty Echo 程序

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#java echo程序

本文介绍了如何使用Java的Netty框架构建一个Echo服务器和客户端。服务器端接收到客户端发送的信息后会原样返回，客户端则发送'Hello, Netty!'并监听接收回应。代码包括了ServerBootstrap、ChannelInitializer、EchoServerHandler、EchoClientHandler等关键组件的实现。" 132371209,19671472,Android操作系统的历史演变与特性,"['Android开发', '操作系统历史', '移动应用']

使用 Netty 实现的 Echo 程序：客户端发送信息，服务端原样返回。

1.服务端package com.learn.netty.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;

public class EchoServer {

private final int port;

public EchoServer(int port) {

this.port = port;

}

public static void main(String[] args) throws Exception {

new EchoServer(8888).start();

}

public void start() throws Exception {

final EchoServerHandler serverHandler = new EchoServerHandler();

EventLoopGroup group = new NioEventLoopGroup();

try {

ServerBootstrap bootstrap = new ServerBootstrap();

bootstrap.group(group)

.channel(NioServerSocketChannel.class)

.localAddress(new InetSocketAddress(port))

.childHandler(new ChannelInitializer() {

protected void initChannel(SocketChannel socketChannel) throws Exception {

socketChannel.pipeline().addLast(serverHandler);

}

});

ChannelFuture future = bootstrap.bind().sync();

future.channel().closeFuture().sync();

} finally {

group.shutdownGracefully().sync();

}

2.服务端Handlerpackage com.learn.netty.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 java.nio.charset.Charset;

@ChannelHandler.Sharable

public class EchoServerHandler extends ChannelInboundHandlerAdapter {

@Override

public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {

ByteBuf in = (ByteBuf) msg;

System.out.println("Server received: " + in.toString(Charset.defaultCharset()));

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();

}

3.客户端package com.learn.netty.echo;

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;

import java.net.InetSocketAddress;

public class EchoClient {

private final String host;

private final int port;

public EchoClient(String host, int port) {

this.host = host;

this.port = port;

}

public static void main(String[] args) throws Exception {

new EchoClient("127.0.0.1", 8888).start();

}

public void start() throws Exception {

EventLoopGroup group = new NioEventLoopGroup();

try {

Bootstrap bootstrap = new Bootstrap();

bootstrap.group(group)

.channel(NioSocketChannel.class)

.remoteAddress(new InetSocketAddress(host, port))

.handler(new ChannelInitializer() {

protected void initChannel(SocketChannel socketChannel) throws Exception {

socketChannel.pipeline().addLast(new EchoClientHandler());

}

});

ChannelFuture future = bootstrap.connect().sync();

future.channel().closeFuture().sync();

} finally {

group.shutdownGracefully().sync();

}

4.客户端Handlerpackage com.learn.netty.echo;

import io.netty.buffer.ByteBuf;

import io.netty.buffer.Unpooled;

import io.netty.channel.ChannelFuture;

import io.netty.channel.ChannelFutureListener;

import io.netty.channel.ChannelHandlerContext;

import io.netty.channel.SimpleChannelInboundHandler;

import io.netty.util.CharsetUtil;

public class EchoClientHandler extends SimpleChannelInboundHandler {

@Override

public void channelActive(ChannelHandlerContext ctx) throws Exception {

ctx.writeAndFlush(Unpooled.copiedBuffer("Hello, Netty!", CharsetUtil.UTF_8))

.addListener(new ChannelFutureListener() {

@Override

public void operationComplete(ChannelFuture channelFuture) throws Exception {

if (channelFuture.isSuccess()) {

System.out.println("Success!");

} else {

System.out.println("Fail!");

channelFuture.cause().printStackTrace();

}

});

}

protected void channelRead0(ChannelHandlerContext channelHandlerContext, ByteBuf in) throws Exception {

System.out.println("Client received: " + in.toString(CharsetUtil.UTF_8));

}

@Override

public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {

cause.printStackTrace();

ctx.close();

}