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,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：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。
