声明

该系列文章由书籍《Netty权威指南》第二版整理而来。只为记录学习笔记。
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[TOC]

时间服务器--AIO

服务端代码

服务端主程序

public class TimeServer {

    public static void main(String[] args) throws IOException {
        int port = 1234;
        new Thread(new TimeServerHandler(port)).start();
    }
}

服务端处理程序

public class TimeServerHandler implements Runnable {

    private int port;

    private CountDownLatch latch;
    private AsynchronousServerSocketChannel asynchronousServerSocketChannel;

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

    @Override
    public void run() {

        this.latch = new CountDownLatch(1);
        doAccept();
        try {
            this.latch.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    private void doAccept() {
        this.asynchronousServerSocketChannel.accept(this,
                new CompletionHandler<AsynchronousSocketChannel, TimeServerHandler>() {

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

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

//  public AsynchronousServerSocketChannel getAsynchronousServerSocketChannel() {
//      return asynchronousServerSocketChannel;
//  }
//
//  public void setAsynchronousServerSocketChannel(AsynchronousServerSocketChannel asynchronousServerSocketChannel) {
//      this.asynchronousServerSocketChannel = asynchronousServerSocketChannel;
//  }
//
//  public CountDownLatch getLatch() {
//      return latch;
//  }
//
//  public void setLatch(CountDownLatch latch) {
//      this.latch = latch;
//  }

}

服务端处理程序

public class TimeServerReadCompletionHandler implements CompletionHandler<Integer, ByteBuffer> {

    private AsynchronousSocketChannel channel;
    private DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

    public TimeServerReadCompletionHandler(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("request msg is : " + req);
            doWrite(this.df.format(new Date()));
        } 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) {
                    if (buffer.hasRemaining())
                        channel.write(buffer, buffer, this);
                }

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

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

}

客户端代码

客户端主程序

public class TimeClient {

    public static void main(String[] args) {
        int port = 1234;
        new Thread(new TimeClientHandler("127.0.0.1", port)).start();
    }
}

客户端处理类

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

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

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

    @Override
    public void run() {

        latch = new CountDownLatch(1);
        asc.connect(new InetSocketAddress(host, port), this, this);
        try {
            latch.await();
        } catch (InterruptedException e1) {
            e1.printStackTrace();
        }
        try {
            asc.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void completed(Void result, TimeClientHandler attachment) {
        byte[] req = "Hi Server !".getBytes();
        ByteBuffer writeBuffer = ByteBuffer.allocate(req.length);
        writeBuffer.put(req);
        writeBuffer.flip();
        asc.write(writeBuffer, writeBuffer, new CompletionHandler<Integer, ByteBuffer>() {
            @Override
            public void completed(Integer result, ByteBuffer buffer) {
                if (buffer.hasRemaining()) {
                    asc.write(buffer, buffer, this);
                } else {
                    ByteBuffer readBuffer = ByteBuffer.allocate(1024);
                    asc.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("Now is : " + body);
                                latch.countDown();
                            } catch (UnsupportedEncodingException e) {
                                e.printStackTrace();
                            }
                        }

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

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

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

}

总结

这种AIO模型有如下特点:

• 代码复杂
• 调试困难

参考资料: 《Netty权威指南》第二版