netty之管道處理流程

　　1、我們在使用netty的是有都會存在將channelBuffer的數據處理成相應的String或者自定義數據。而這里主要是介紹管道里面存在的上行和下行的數據處理方式

　　2、通過一張圖片來看一下具體管道中的實現過程

　　

　　一個Channel中包括一個Socket、一個ChannelPipeline。一個ChannelPipeline中有一個ChannelSink和多個ChannelHandler。ChannelHandler分為兩種：UpstremHandler、DownstreamHandler。

　　不論是讀數據還是寫數據都要經過Channel中的ChannelPipeline。讀數據的過程是從Socket到ChannelPipeline，由ChannelPipeline交給里面的UpstreamHandler（或者叫做InBoundHandler）從下到上依次處理 。寫數據時，由要經過ChannelPipeline里面在DownStreamHandler（或者是OutBoundHandler）由上到下依次處理。

　　3、因為UpstremHandler與DownstreamHandler的實現方式大同小異，我這里寫的例子是UpstremHandler的例子

package com.troy.application.upstream;


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.timeout.IdleStateHandler;
import org.jboss.netty.util.HashedWheelTimer;

import java.net.InetSocketAddress;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class Server {

    public static void main(String[] args) {

        //聲明服務類
        ServerBootstrap serverBootstrap = new ServerBootstrap();

        //設定線程池
        ExecutorService boss = Executors.newCachedThreadPool();
        ExecutorService work = Executors.newCachedThreadPool();

        //設置工廠
        serverBootstrap.setFactory(new NioServerSocketChannelFactory(boss,work));

        //設置管道流
        serverBootstrap.setPipelineFactory(new ChannelPipelineFactory() {
            @Override
            public ChannelPipeline getPipeline() throws Exception {
                ChannelPipeline channelPipeline = Channels.pipeline();
                //添加處理方式
                channelPipeline.addLast("idle",new IdleStateHandler(new HashedWheelTimer(),5,5,10));
                channelPipeline.addLast("handler1",new Handler1());
                channelPipeline.addLast("handler2",new Handler2());
                return channelPipeline;
            }
        });

        //設置端口
        serverBootstrap.bind(new InetSocketAddress(9000));
    }
}

package com.troy.application.upstream;

import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelHandler;
import org.jboss.netty.channel.UpstreamMessageEvent;

public class Handler1 extends SimpleChannelHandler {
    @Override
    public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
        ChannelBuffer channelBuffer = (ChannelBuffer) e.getMessage();
        byte[] array = channelBuffer.array();
        String message = new String(array);
        System.out.println("handler1"+message);
        ctx.sendUpstream(new UpstreamMessageEvent(ctx.getChannel(),message,e.getRemoteAddress()));
    }
}

package com.troy.application.upstream;

import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelHandler;

public class Handler2 extends SimpleChannelHandler {
    @Override
    public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
        String message = (String) e.getMessage();
        System.out.println("handler2"+message);
    }
}

　　說明：這里最重要的兩個方法是sendUpstream和sendDownstream。這兩個方式在上行和下行的處理基本上是一樣的。在源碼里面handler的處理都會存在sendUpstream和sendDownstream。這個兩個方法也是多重處理的基礎。