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<SocketChannel>() { @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 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(); } } 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<SocketChannel>() { @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：26156158*458918+125615客户端发送消息：156158*458918+125615服务器消息：7.1663842659E101895612+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。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。