Netty之HelloWorld!
为什么要使用Netty?
Netty是一个基于NIO的简化版,使用Netty更方便使用Java进行异步操作。
传统的IO:
NIO:
从图上就可以看出来,NIO简化了不必要的线程连接,以往的Socket每多一个连接,都需要创建一个线程,这是一个额外的消耗,因此Java在1.4之后推出了NIO,用于简化线程操作。
NIO可以理解为New IO,也可以理解为Non-Blocking IO。
但由于NIO操作繁琐,而且API不易使用,因此Netty便应空而生,Netty是为了简化NIO而诞生的框架。
以下是一个Netty的HelloWorld示例:
Netty服务端:
package com.netty.server;
import java.net.InetSocketAddress;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import org.jboss.netty.bootstrap.ServerBootstrap;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineFactory;
import org.jboss.netty.channel.Channels;
import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory;
import org.jboss.netty.handler.codec.string.StringDecoder;
import org.jboss.netty.handler.codec.string.StringEncoder;
/**
* netty服务端入门
* @author 小书包
*
*/
public class Server {
public static final int PORT = 10101;
public static void main(String[] args) {
//服务类
ServerBootstrap bootstrap = new ServerBootstrap();
//boss线程监听端口,worker线程负责数据读写
ExecutorService boss = Executors.newCachedThreadPool();
ExecutorService worker = Executors.newCachedThreadPool();
//设置nioSocket工厂
bootstrap.setFactory(new NioServerSocketChannelFactory(boss, worker));
//设置管道的工厂
bootstrap.setPipelineFactory(new ChannelPipelineFactory() {
@Override
public ChannelPipeline getPipeline() throws Exception {
//获得管道
ChannelPipeline pipeline = Channels.pipeline();
//字符串解码
pipeline.addLast("decoder", new StringDecoder());
//字符串编码
pipeline.addLast("encoder", new StringEncoder());
//具体的事件处理器
pipeline.addLast("helloHandler", new HelloHandler());
return pipeline;
}
});
//绑定端口
bootstrap.bind(new InetSocketAddress(PORT));
System.out.println(" Server Start On " + PORT + "!!!");
}
}
事件处理器
package com.netty.server;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelStateEvent;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelHandler;
/**
* 消息接受处理类
* @author 小书包
*
*/
public class HelloHandler extends SimpleChannelHandler {
/**
* 接收消息
*/
@Override
public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
String s = (String) e.getMessage();
System.out.println(s);
//回写数据
ctx.getChannel().write("hi");
super.messageReceived(ctx, e);
}
/**
* 捕获异常
*/
@Override
public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception {
System.out.println("exceptionCaught");
super.exceptionCaught(ctx, e);
}
/**
* 新连接
*/
@Override
public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
System.out.println("channelConnected");
super.channelConnected(ctx, e);
}
/**
* 必须是链接已经建立,关闭通道的时候才会触发
*/
@Override
public void channelDisconnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
System.out.println("channelDisconnected");
super.channelDisconnected(ctx, e);
}
/**
* channel关闭的时候触发
*/
@Override
public void channelClosed(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
System.out.println("channelClosed");
super.channelClosed(ctx, e);
}
}
启动Server
Server Start On 10101!!!
使用Telnet进行连接
进入连接
channelConnected
输入send hello
服务端得到:
hello
并发送Hi到客户端
关闭Telnet
channelDisconnected
channelClosed
如果不使用Telent,使用Java代码进行连接
客户端代码
package com.netty.client;
import java.net.InetSocketAddress;
import java.util.Scanner;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import org.jboss.netty.bootstrap.ClientBootstrap;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelFuture;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineFactory;
import org.jboss.netty.channel.Channels;
import org.jboss.netty.channel.socket.nio.NioClientSocketChannelFactory;
import org.jboss.netty.handler.codec.string.StringDecoder;
import org.jboss.netty.handler.codec.string.StringEncoder;
/**
* netty客户端入门
* @author 小书包
*
*/
public class Client {
public static void main(String[] args) {
//服务类
ClientBootstrap bootstrap = new ClientBootstrap();
//线程池
ExecutorService boss = Executors.newCachedThreadPool();
ExecutorService worker = Executors.newCachedThreadPool();
//socket工厂
bootstrap.setFactory(new NioClientSocketChannelFactory(boss, worker));
//管道工厂
bootstrap.setPipelineFactory(new ChannelPipelineFactory() {
@Override
public ChannelPipeline getPipeline() throws Exception {
ChannelPipeline pipeline = Channels.pipeline();
pipeline.addLast("decoder", new StringDecoder());
pipeline.addLast("encoder", new StringEncoder());
pipeline.addLast("hiHandler", new HiHandler());
return pipeline;
}
});
//连接服务端
ChannelFuture connect = bootstrap.connect(new InetSocketAddress("127.0.0.1", 10101));
Channel channel = connect.getChannel();
System.out.println("client start");
Scanner scanner = new Scanner(System.in);
while(true){
System.out.println("请输入");
channel.write(scanner.next());
}
}
}
事件处理器
package com.netty.client;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelStateEvent;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelHandler;
/**
* 消息接受处理类
* @author 小书包
*
*/
public class HiHandler extends SimpleChannelHandler {
/**
* 接收消息
*/
@Override
public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
String s = (String) e.getMessage();
System.out.println(s);
super.messageReceived(ctx, e);
}
/**
* 捕获异常
*/
@Override
public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception {
System.out.println("exceptionCaught");
super.exceptionCaught(ctx, e);
}
/**
* 新连接
*/
@Override
public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
System.out.println("channelConnected");
super.channelConnected(ctx, e);
}
/**
* 必须是链接已经建立,关闭通道的时候才会触发
*/
@Override
public void channelDisconnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
System.out.println("channelDisconnected");
super.channelDisconnected(ctx, e);
}
/**
* channel关闭的时候触发
*/
@Override
public void channelClosed(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
System.out.println("channelClosed");
super.channelClosed(ctx, e);
}
}