AIO通信

一、AIO简介

HDK推出的NIO2.0也叫AIO引入了新的异步通道的概念，并提供了异步文件通道和异步套接字通道的实现。AIO的异步套接字通道是真正的异步非阻塞IO，对应于UNIX网络编程中的事件驱动IO（AIO）。它不需要通过多路复用器Selector对注册的通道进行轮询操作即可实现异步读写，从而简化了NIO的编程模型。

二、代码实例

2.1 服务端

TimeServer.java

package com.wangjun.io.aio;
/**
 * @author wangjun
 * @date 2020-04-01
 * @version 1.0
 */
public class TimeServer {

    public static void main(String[] args) {
        int port = 8080;
        AsynTimeServerHandler timeServer = new AsynTimeServerHandler(port);
        new Thread(timeServer, "AIO-AsynTimeServerHandler-001").start();
    }

}

AsynTimeServerHandler.java

package com.wangjun.io.aio;

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

/**
 * @author wangjun
 * @date 2020-04-01
 * @version 1.0
 */
public class AsynTimeServerHandler implements Runnable {

    CountDownLatch latch;
    AsynchronousServerSocketChannel asynchronousServerSocketChannel;

    public AsynTimeServerHandler(int port) {
        try {
            asynchronousServerSocketChannel = AsynchronousServerSocketChannel.open();
            asynchronousServerSocketChannel.bind(new InetSocketAddress(port));
            System.out.println("The time server start in port:" + port);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        latch = new CountDownLatch(1);
        doAccept();
        try {
            latch.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

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

}

AcceptCompletionHandler.java

package com.wangjun.io.aio;

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

/**
 * @author wangjun
 * @date 2020-04-01
 * @version 1.0
 */
public class AcceptCompletionHandler implements CompletionHandler<AsynchronousSocketChannel, AsynTimeServerHandler> {

    @Override
    public void completed(AsynchronousSocketChannel result, AsynTimeServerHandler attachment) {
        attachment.asynchronousServerSocketChannel.accept(attachment, this);
        ByteBuffer buffer = ByteBuffer.allocate(1024);
        result.read(buffer, buffer, new ReadCompletionHandler(result));
    }

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

}

ReadCompletionHandler.java

package com.wangjun.io.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;

/**
 * @author wangjun
 * @date 2020-04-01
 * @version 1.0
 */
public class ReadCompletionHandler implements CompletionHandler<Integer, ByteBuffer> {

    private AsynchronousSocketChannel channel;

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

    @Override
    public void completed(Integer result, ByteBuffer attachment) {
        attachment.flip();
        byte[] body = new byte[attachment.remaining()];
        attachment.get(body);
        try {
            String req = new String(body, "UTF-8");
            System.out.println("服务端收到的命令是：" + req);
            String currentTime = "QUERY TIME ORDER".equalsIgnoreCase(req)
                    ? new Date(System.currentTimeMillis()).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();
            ByteBuffer writeBuffer = ByteBuffer.allocate(bytes.length);
            writeBuffer.put(bytes);
            writeBuffer.flip();
            channel.write(writeBuffer, writeBuffer, new CompletionHandler<Integer, ByteBuffer>() {

                @Override
                public void completed(Integer result, ByteBuffer buffer) {
                    //如果没有发送完成，继续发送
                    if(buffer.hasRemaining()) {
                        channel.write(buffer, buffer, this);
                    }
                }

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

            });
        }
    }

    @Override
    public void failed(Throwable paramThrowable, ByteBuffer paramA) {
        try {
            this.channel.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}

2.2 客户端

TimeClient.java

package com.wangjun.io.aio;

public class TimeClient {

    public static void main(String[] args) throws InterruptedException {
        int port = 8080;

        new Thread(new AsynTimeClientHandler("127.0.0.1", port), "AsynTimeClientHandler-001").start();
    }

}

AsynTimeClientHandler.java

package com.wangjun.io.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;

/**
 * @author wangjun
 * @date 2020-04-01
 * @version 1.0
 */
public class AsynTimeClientHandler implements CompletionHandler<Void, AsynTimeClientHandler>, Runnable {

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

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

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

    @Override
    public void completed(Void result, AsynTimeClientHandler attachment) {
        byte[] req = "QUERY TIME ORDER".getBytes();
        ByteBuffer writeBuffer = ByteBuffer.allocate(req.length);
        writeBuffer.put(req);
        writeBuffer.flip();
        client.write(writeBuffer, writeBuffer, new CompletionHandler<Integer, ByteBuffer>() {

            @Override
            public void completed(Integer result, ByteBuffer buffer) {
                if(buffer.hasRemaining()) {
                    client.write(buffer, buffer, this);
                }else {
                    ByteBuffer readBuffer = ByteBuffer.allocate(1024);
                    client.read(readBuffer, readBuffer, new CompletionHandler<Integer, ByteBuffer>() {

                        @Override
                        public void completed(Integer result, ByteBuffer buffer) {
                            buffer.flip();
                            byte[] bytes = new byte[buffer.remaining()];
                            buffer.get(bytes);
                            String body;
                            try {
                                body = new String(bytes, "UTF-8");
                                System.out.println("现在是：" + body);
                                latch.countDown();
                            } catch (UnsupportedEncodingException e) {
                                e.printStackTrace();
                            }
                        }

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

                    });
                }
            }

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

        });
    }

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

}