Java NIO框架Netty简单使用的示例

Java NIO框架Netty简单使用的示例

之前写了一篇文章：java 网络IO编程总结（BIO、NIO、AIO均含完整实例代码），介绍了如何使用Java原生IO支持进行网络编程，本文介绍一种更为简单的方式，即Java NIO框架。

Netty是业界最流行的NIO框架之一，具有良好的健壮性、功能、性能、可定制性和可扩展性。同时，它提供的十分简单的API，大大简化了我们的网络编程。

同Java IO介绍的文章一样，本文所展示的例子，实现了一个相同的功能。

1、服务端

Server：

package com.anxpp.io.calculator.netty;

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;

public class Server {

private int port;

public Server(int port) {

this.port = port;

}

public void run() throws Exception {

EventLoopGroup bossGroup = new NioEventLoopGroup();

EventLoopGroup workerGroup = new NioEventLoopGroup();

try {

ServerBootstrap b = new ServerBootstrap();

b.group(bossGroup, workerGroup)

.channel(NioServerSocketChannel.class)

.option(ChannelOption.SO_BACKLOG, 1024)

.childOption(ChannelOption.SO_KEEPALIVE, true)

.childHandler(new ChannelInitializer() {

@Override

public void initChannel(SocketChannel ch) throws Exception {

ch.pipeline().addLast(new ServerHandler());

}

});

ChannelFuture f = b.bind(port).sync();

System.out.println("服务器开启："+port);

f.channel().closeFuture().sync();

} finally {

workerGroup.shutdownGracefully();

bossGroup.shutdownGracefully();

}

}

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

int port;

if (args.length > 0) {

port = Integer.parseInt(args[0]);

} else {

port = 9090;

}

new Server(port).run();

}

}

ServerHandler：

package com.anxpp.io.calculator.netty;

import io.netty.buffer.ByteBuf;

import io.netty.buffer.Unpooled;

import io.netty.channel.ChannelHandlerContext;

import io.netty.channel.ChannelInboundHandlerAdapter;

import java.io.UnsupportedEncodingException;

import com.anxpp.io.utils.Calculator;

public class ServerHandler extends ChanBYIJlGUnelInboundHandlerAdapter {

@Override

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

ByteBuf in = (ByteBuf) msg;

byte[] req = new byte[in.readableBytes()];

in.readBytes(req);

String body = new String(req,"utf-8");

System.out.println("收到客户端消息:"+body);

String calrResult = null;

try{

calrResult = Calculator.Instance.cal(body).toString();

}catch(Exception e){

calrResult = "错误的表达式：" + e.getMessage();

}

ctx.write(Unpooled.copiedBuffer(calrResult.getBytes()));

}

@Override

public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {

ctx.flush();

}

/**

* 异常处理

*/

@Override

public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {

cause.printStackTrace();

ctx.close();

}

}

package com.anxpp.io.calculator.netty;

import io.netty.buffer.ByteBuf;

import io.netty.buffer.Unpooled;

import io.netty.channel.ChannelHandlerContext;

import io.netty.channel.ChannelInboundHandlerAdapter;

import java.io.UnsupportedEncodingException;

import com.anxpp.io.utils.Calculator;

public class ServerHandler extends ChannelInboundHandlerAdapter {

@Override

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

ByteBuf in = (ByteBuf) msg;

byte[] req = new byte[in.readableBytes()];

in.readBytes(req);

String body = new String(req,"utf-8");

System.out.println("收到客户端消息:"+body);

String calrResult = null;

try{

calrResult = Calculator.Instance.cal(body).toString();

}catch(Exception e){

calrResult = "错误的表达式：" + e.getMessage();

}

ctx.write(Unpooled.copiedBuffer(calrResult.getBytes()));

}

@Override

public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {

ctx.flush();

}

/**

* 异常处理

*/

@Override

public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {

cause.printStackTrace();

ctx.close();

}

}

2、客户端

Client：

package com.anxpp.io.calculator.netty;

import io.netty.bootstrap.Bootstrap;

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.NioSocketChannel;

import java.util.Scanner;

public class Client implements Runnable{

static ClientHandler client = new ClientHandler();

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

new Thread(new Client()).start();

@SuppressWarnings("resource")

Scanner scanner = new Scanner(System.in);

while(client.sendMsg(scanner.nextLine()));

}

@Override

public void run() {

String host = "127.0.0.1";

int port = 9090;

EventLoopGroup workerGroup = new NioEventLoopGroup();

try {

Bootstrap b = new Bootstrap();

b.group(workerGroup);

b.channel(NioSocketChannel.class);

b.option(ChannelOption.SO_KEEPALIVE, true);

b.handler(new ChannelInitializer() {

@Override

public void initChannel(SocketChannel ch) throws Exception {

ch.pipeline().addLast(client);

}

});

ChannelFuture f = b.connect(host, port).sync();

f.channel().closeFuture().sync();

} catch (InterruptedException e) {

e.printStackTrace();

} finally {

workerGroup.shutdownGracefully();

}

}

}

ClientHandler：

package com.anxpp.io.calculator.netty;

import io.netty.buffer.ByteBuf;

import io.netty.buffer.Unpooled;

import io.netty.channel.ChannelHandlerContext;

import io.netty.channel.ChannelInboundHandlerAdapter;

import java.io.UnsupportedEncodingException;

public class ClientHandler extends ChannelInboundHandlerAdapter {

ChannelHandlerContext ctx;

/**

* tcp链路简历成功后调用

*/

@Override

public void channelActive(ChannelHandlerContext ctx) throws Exception {

this.ctx = ctx;

}

public boolean sendMsg(String msg){

System.out.println("客户端发送消息："+msg);

byte[] req = msg.getBytes();

ByteBuf m = Unpooled.buffer(req.length);

m.writeBytes(req);

ctx.writeAndFlush(m);

return msg.equals("q")?false:true;

}

/**

* 收到服务器消息后调用

* @throws UnsupportedEncodingException

*/

@Override

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

ByteBuf buf = (ByteBuf) msg;

byte[] req = new byte[buf.readableBytes()];

buf.readBytes(req);

String body = new String(req,"utf-8");

System.out.println("服务器消息："+body);

}

/**

* 发生异常时调用

*/

@Override

public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {

cause.printStackTrace();

ctx.close();

}

}

3、用于计算的工具类

package com.anxpp.io.utils;

import javax.script.ScriptEngine;

import javax.script.ScriptEngineManager;

import javax.script.ScriptException;

public enum Calculator {

Instance;

private final static ScriptEngine jse = new ScriptEngineManager().getEngineByName("javascript");

public Object cal(String expression) throws ScriptException{

return jse.eval(expression);

}

}

4、测试

分别启动服务端和客户端，然后再客户端控制台输入表达式：

1+5+5+5+5+5

客户端发送消息：1+5+5+5+5+5

服务器消息：26

156158*458918+125615

客户端发送消息：156158*458918+125615

服务器消息：7.1663842659E10

1895612+555+5+5+5+5+5+5+5-5*4/4

客户端发送消息：1895612+555+5+5+5+5+5+5+5-5*4/4

服务器消息：1896197

可以看到服务端返回的结果。

查看服务端控制台：

服务器开启：9090

收到客户端消息:1+5+5+5+5+5

收到客户端消息:156158*458918+125615

收到客户端消息:1895612+555+5+5+5+5+5+5+5-5*4/4

5、更多

相关文章：

Java 网络IO编程总结（BIO、NIO、AIO均含完整实例代码）

本文例子以及Java BIO NIO AIO例子的源码Git地址：https://github.com/anxpp/Java-IO.git

后续会继续更新Netty相关内容，直到一个简陋的通讯服务器完成。

版权声明：本文内容由网络用户投稿，版权归原作者所有，本站不拥有其著作权，亦不承担相应法律责任。如果您发现本站中有涉嫌抄袭或描述失实的内容，请联系我们jiasou666@gmail.com 处理，核实后本网站将在24小时内删除侵权内容。