之前寫了一篇文章：Java 網絡IO編程總結（BIO、NIO、AIO均含完整實例代碼），介紹了如何使用Java原生IO支持進行網絡編程，本文介紹一種更為簡單的方式，即Java NIO框架。
Netty是業界最流行的NIO框架之一，具有良好的健壯性、功能、性能、可定制性和可擴展性。同時，它提供的十分簡單的API，大大簡化了我們的網絡編程。
同Java IO介紹的文章一樣，本文所展示的例子，實現了一個相同的功能。
1、服務端
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("服務器開啟："+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("收到客戶端消息:"+body); String calrResult = null; try{ calrResult = Calculator.Instance.cal(body).toString(); }catch(Exception e){ calrResult = "錯誤的表達式：" + e.getMessage(); } ctx.write(Unpooled.copiedBuffer(calrResult.getBytes())); } @Override public void channelReadComplete(ChannelHandlerContext ctx) throws Exception { ctx.flush(); } /** * 異常處理 */ @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("收到客戶端消息:"+body); String calrResult = null; try{ calrResult = Calculator.Instance.cal(body).toString(); }catch(Exception e){ calrResult = "錯誤的表達式：" + e.getMessage(); } ctx.write(Unpooled.copiedBuffer(calrResult.getBytes())); } @Override public void channelReadComplete(ChannelHandlerContext ctx) throws Exception { ctx.flush(); } /** * 異常處理 */ @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) { cause.printStackTrace(); ctx.close(); } } 2、客戶端
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鏈路簡歷成功后調用 */ @Override public void channelActive(ChannelHandlerContext ctx) throws Exception { this.ctx = ctx; } public boolean sendMsg(String msg){ System.out.println("客戶端發送消息："+msg); byte[] req = msg.getBytes(); ByteBuf m = Unpooled.buffer(req.length); m.writeBytes(req); ctx.writeAndFlush(m); return msg.equals("q")?false:true; } /** * 收到服務器消息后調用 * @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("服務器消息："+body); } /** * 發生異常時調用 */ @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) { cause.printStackTrace(); ctx.close(); } } 3、用于計算的工具類
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、測試
分別啟動服務端和客戶端，然后再客戶端控制臺輸入表達式：
1+5+5+5+5+5客戶端發送消息：1+5+5+5+5+5服務器消息：26156158*458918+125615客戶端發送消息：156158*458918+125615服務器消息：7.1663842659E101895612+555+5+5+5+5+5+5+5-5*4/4客戶端發送消息：1895612+555+5+5+5+5+5+5+5-5*4/4服務器消息：1896197
可以看到服務端返回的結果。
查看服務端控制臺：
服務器開啟：9090收到客戶端消息:1+5+5+5+5+5收到客戶端消息:156158*458918+125615收到客戶端消息:1895612+555+5+5+5+5+5+5+5-5*4/4
5、更多
相關文章：
Java 網絡IO編程總結（BIO、NIO、AIO均含完整實例代碼）
本文例子以及Java BIO NIO AIO例子的源碼Git地址：https://github.com/anxpp/Java-IO.git
后續會繼續更新Netty相關內容，直到一個簡陋的通訊服務器完成。
以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持VeVb武林網。
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