网络编程 AIO

开始接收客户端的连接，连接成功或者失败都是触发CompletionHandler对象的响应方法。

CompletionHandler接口提供了两个方法：

void completed(V result, A attachment);

当IO完成时触发该方法，该方法的第一个参数代表IO操作的返回的对象，第二个参数代表发起IO操作时传入的附加参数。

void failed(Throwable exc, A attachment);

当IO失败时触发该方法，第一个参数表示IO操作失败引起的异常或错误，第二个参数代表发起IO操作时传入的附加参数。

即提交一个IO操作请求(Accept/read/write)，指定一个CompletionHandler，当异步IO操作完成时，发送一个通知，这个时候CompletionHandler对象的completed或者failed方法将会被调用。

AIO的实现需要充分调用操作系统参数，IO需要操作系统的支持，并发也同样需要操作系统的支持，所以性能方面不同的操作系统差异会比较明显。

AIO 的回调方式编程

AIO服务端（Server.java）：

/*** AIO服务端代码* @Author : quwenjing* @Date : 2021/11/18 19:01**/
public class Server {public static void main(String[] args) {try {//创建服务端通道AsynchronousServerSocketChannel asynchronousServerSocketChannel = AsynchronousServerSocketChannel.open();//绑定端口asynchronousServerSocketChannel.bind(new InetSocketAddress(6666));System.out.println("服务端启动");//接受客户端的连接acceptasynchronousServerSocketChannel.accept(null,new AcceptCompletionHandler(asynchronousServerSocketChannel));//BIO accept操作返回Socket实例//AIO accept操作返回AsynchronousSocketChannel
​//accept是异步操作，防止当前程序直接执行结束//方法一：while(ture) +sleepwhile (true){try {Thread.sleep(1000);} catch (InterruptedException e) {e.printStackTrace();}}} catch (IOException e) {e.printStackTrace();}}
}

接受连接accept的回调(AcceptCompletionHandler.java)：

/*** 接收连接accept的回调* @Author : quwenjing* @Date : 2021/11/18 19:07**/
public class AcceptCompletionHandler implements CompletionHandler {
//返回参数，传入参数
​private AsynchronousServerSocketChannel channel;public AcceptCompletionHandler(AsynchronousServerSocketChannel channel){this.channel = channel;}@Overridepublic void completed(AsynchronousSocketChannel result, Object attachment) {System.out.println("有新客户的连接");//完成accept连接操作//读写操作，需要使用buffer//创建新的bufferByteBuffer byteBuffer = ByteBuffer.allocate(1024);//读客户端的数据，读操作是异步操作,需要实现CompletionHandler对象/*void read(ByteBuffer dst,A attachment,CompletionHandler handler);读操作异步方式方法解读dst：数据读取目的地    attachment：给读回调传递的信息CompletionHandler：当读数据完成后CompletionHandler对象*/result.read(byteBuffer,byteBuffer,new ReadCompletionHandler(result));
​//再次接受其他客户端的连接，调用accept方法channel.accept(null,new AcceptCompletionHandler(channel));}@Overridepublic void failed(Throwable exc, Object attachment) {
​}
}

读操作的回调(ReadCompletionHandler.java)：

/*** 读操作的回调* @Author : quwenjing* @Date : 2021/11/18 19:21**/
public class ReadCompletionHandler implements CompletionHandler {//读操作返回的结果是读取的个数，应该是Integer
​//用户接收或者发送操作的通道private AsynchronousSocketChannel asynchronousSocketChannel;public ReadCompletionHandler(AsynchronousSocketChannel channel){this.asynchronousSocketChannel = channel;}@Overridepublic void completed(Integer result, ByteBuffer attachment) {//读数据完成后//数据已经完成并写入ByteBuffer类型的result变量中attachment.flip();byte[] bytes = new byte[attachment.remaining()];attachment.get(bytes);String string = null;try {string = new String(bytes,"utf-8");} catch (UnsupportedEncodingException e) {e.printStackTrace();}System.out.println("服务端接收的数据:"+string);attachment.clear();
​//重复接收消息，再次调用异步读操作this.asynchronousSocketChannel.read(attachment,attachment,new ReadCompletionHandler(this.asynchronousSocketChannel));}@Overridepublic void failed(Throwable exc, ByteBuffer attachment) {
​}
}
​

客户端(Client.java):

public class Client {public static void main(String[] args) {//创建异步通道try {AsynchronousSocketChannel asynchronousSocketChannel = AsynchronousSocketChannel.open();
​//连接服务端异步方式asynchronousSocketChannel.connect(new InetSocketAddress("127.0.0.1",6666),asynchronousSocketChannel,new ConnectionCompletionHandler());
​ByteBuffer byteBuffer = ByteBuffer.allocate(1024);//写操作Scanner scanner = new Scanner(System.in);while (scanner.hasNext()){String msg = scanner.nextLine();if (msg!=null && !"".equals(msg.trim())){byteBuffer.put(msg.getBytes());byteBuffer.flip();asynchronousSocketChannel.write(byteBuffer);byteBuffer.clear();}}} catch (IOException e) {e.printStackTrace();}}
}
​

连接服务端(ConnectionCompletionHandler.java)：

public class ConnectionCompletionHandler implements CompletionHandler {@Overridepublic void completed(Void result, AsynchronousSocketChannel attachment) {//连接服务端成功System.out.println("连接服务端成功");}
​@Overridepublic void failed(Throwable exc, AsynchronousSocketChannel attachment) {
​}
}
​