Netty权威指南之AIO编程

由JDK1.7提供的NIO2.0新增了异步的套接字通道，它是真正的异步I/O，在异步I/O操作的时候可以传递信号变量，当操作完成后会回调相关的方法，异步I/o也被称为AIO，对应于UNIX网络编程中的事件驱动I/O；不再需要通过多路复用器（Selector）对注册的通道进行轮询操作就可以实现异步读写

package com.hjp.netty.aio;

import java.io.IOException;

public class TimeServer {

    public static void main(String[] args)throws IOException{
        int port=8080;
        if (args!=null&&args.length>0){
           try {
               port=Integer.valueOf(args[0]);
           }catch (NumberFormatException e){

           }
        }
        AsyncTimeServerHandler timeServerHandler=new AsyncTimeServerHandler(port);
        new Thread(timeServerHandler,"AIOServer").start();
    }

}

TimeServer

package com.hjp.netty.aio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.channels.AsynchronousServerSocketChannel;
import java.util.concurrent.CountDownLatch;

/**
 * Created by JiaPeng on 2017/7/24.
 */
public class AsyncTimeServerHandler implements Runnable {

    private int port;

    CountDownLatch latch;
    AsynchronousServerSocketChannel asynchronousServerSocketChannel;

    public AsyncTimeServerHandler(int port) {
        this.port = port;
        try {
            asynchronousServerSocketChannel = AsynchronousServerSocketChannel.open();
            //绑定监听端口
            asynchronousServerSocketChannel.bind(new InetSocketAddress(port));
            System.out.println("The time server is start in port : " + port);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        //CountDownLatch作用是完成一组正在执行的操作之前，允许当前的线程一直阻塞，
        //实际项目中不需要独立启动一个线程来处理的
        latch=new CountDownLatch(1);
        doAccept();
        try{
            latch.await();
        }catch (InterruptedException e){
            e.printStackTrace();
        }
    }

    public void doAccept(){
        asynchronousServerSocketChannel.accept(this,new AcceptCompletionHandler());
    }
}

AsyncTimeServerHandler

package com.hjp.netty.aio;

import java.nio.ByteBuffer;
import java.nio.channels.AsynchronousSocketChannel;
import java.nio.channels.CompletionHandler;

public class AcceptCompletionHandler implements CompletionHandler<AsynchronousSocketChannel,AsyncTimeServerHandler> {
    @Override
    public void completed(AsynchronousSocketChannel result, AsyncTimeServerHandler attachment) {
        //再次让asynchronousServerSocketChannel对象调用accept方法是因为：
        //调用AsynchronousServerSocketChannel的accept方法后，如果有新的客户端接入，
        // 系统将回调我们传入的CompletionHandler实例的completed方法，表示新客户端连接成功。
        // 因为AsynchronousServerSocketChannel可以接受成千上万个客户端，所以需要继续调用它的accept方法，
        // 接受其他客户端连接，最终形成一个环；每当一个客户端连接成功后，再异步接受新的客户端连接
        attachment.asynchronousServerSocketChannel.accept(attachment,this);
        ByteBuffer readBuffer=ByteBuffer.allocate(1024);
        result.read(readBuffer,readBuffer,new ReadCompletionHandler(result));
    }

    @Override
    public void failed(Throwable exc, AsyncTimeServerHandler attachment) {
        exc.printStackTrace();
        attachment.latch.countDown();
    }
}

AcceptCompletionHandler

package com.hjp.netty.aio;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import java.nio.channels.AsynchronousSocketChannel;
import java.nio.channels.CompletionHandler;
import java.util.Date;

public class ReadCompletionHandler implements CompletionHandler<Integer, ByteBuffer> {

    private AsynchronousSocketChannel socketChannel;

    public ReadCompletionHandler(AsynchronousSocketChannel socketChannel) {
        if (this.socketChannel == null) {
            this.socketChannel = socketChannel;
        }
    }

    @Override
    public void completed(Integer result, ByteBuffer attachment) {
        attachment.flip();
        byte[] body = new byte[attachment.remaining()];
        attachment.get(body);
        try {
            String request = new String(body, "UTF-8");
            System.out.println("The time server receive order : " + request);
            String currentTime = "QUERY TIME ORDER".equalsIgnoreCase(request) ? new Date().toString() : "BAD ORDER";
            doWrite(currentTime);
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
    }

    private void doWrite(String currentTime) {
        if (currentTime != null && currentTime.trim().length() > 0) {
            byte[] bytes = currentTime.getBytes();
            final ByteBuffer writeBuffer = ByteBuffer.allocate(bytes.length);
            writeBuffer.put(bytes);
            writeBuffer.flip();
            socketChannel.write(writeBuffer, writeBuffer, new CompletionHandler<Integer, ByteBuffer>() {
                @Override
                public void completed(Integer result, ByteBuffer attachment) {
                    //如果没有发送完继续发送
                    if (attachment.hasRemaining()) {
                        socketChannel.write(attachment, attachment, this);
                    }
                }

                @Override
                public void failed(Throwable exc, ByteBuffer attachment) {
                    try {
                        socketChannel.close();
                    } catch (IOException e) {

                    }
                }
            });
        }
    }

    @Override
    public void failed(Throwable exc, ByteBuffer attachment) {
        try {
            socketChannel.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

ReadCompletionHandler

package com.hjp.netty.aio;

public class TimeClient {

    public static void main(String[] args){
        int port=8080;
        if(args!=null&&args.length>0){
            try {
                port=Integer.valueOf(args[0]);
            }catch (NumberFormatException e){

            }
        }
        new Thread(new AsyncTimeClientHandler("127.0.0.1",port),"AIOClient").start();
    }

}

TimeClient

package com.hjp.netty.aio;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.AsynchronousSocketChannel;
import java.nio.channels.CompletionHandler;
import java.util.concurrent.CountDownLatch;

public class AsyncTimeClientHandler implements CompletionHandler<Void, AsyncTimeClientHandler>, Runnable {

    private AsynchronousSocketChannel socketChannel;
    private String host;
    private int port;
    private CountDownLatch latch;

    public AsyncTimeClientHandler(String host,int port){
        this.host=host;
        this.port=port;
        try {
            socketChannel=AsynchronousSocketChannel.open();
        }catch (IOException e){
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        latch=new CountDownLatch(1);
        socketChannel.connect(new InetSocketAddress(host,port),this,this);
        try {
            latch.await();
        }catch (InterruptedException e){
            e.printStackTrace();
        }
        try {
            socketChannel.close();
        }catch (IOException e){
            e.printStackTrace();
        }
    }

    @Override
    public void completed(Void result, AsyncTimeClientHandler attachment) {
        byte[] request="QUERY TIME ORDER".getBytes();
        ByteBuffer writeBuffer=ByteBuffer.allocate(request.length);
        writeBuffer.put(request);
        writeBuffer.flip();
        socketChannel.write(writeBuffer, writeBuffer, new CompletionHandler<Integer, ByteBuffer>() {
            @Override
            public void completed(Integer result, ByteBuffer attachment) {
                if (attachment.hasRemaining()){
                    socketChannel.write(attachment,attachment,this);
                }else {
                    ByteBuffer readBuffer=ByteBuffer.allocate(1024);
                    socketChannel.read(readBuffer, readBuffer, new CompletionHandler<Integer, ByteBuffer>() {
                        @Override
                        public void completed(Integer result, ByteBuffer attachment) {
                            attachment.flip();
                            byte[] bytes=new byte[attachment.remaining()];
                            attachment.get(bytes);
                            try {
                                String body=new String(bytes,"UTF-8");
                                System.out.println("Now is "+body);
                                latch.countDown();
                            }catch (UnsupportedEncodingException e){
                                e.printStackTrace();
                            }

                        }

                        @Override
                        public void failed(Throwable exc, ByteBuffer attachment) {
                            try {
                                socketChannel.close();
                                latch.countDown();
                            }catch (IOException e){

                            }
                        }
                    });
                }
            }

            @Override
            public void failed(Throwable exc, ByteBuffer attachment) {
                try {
                    socketChannel.close();
                    latch.countDown();
                }catch (IOException e){

                }
            }
        });
    }

    @Override
    public void failed(Throwable exc, AsyncTimeClientHandler attachment) {
        exc.printStackTrace();
        try {
            socketChannel.close();
            latch.countDown();
        }catch (IOException e){
            e.printStackTrace();
        }
    }
}

AsyncTimeClientHandler