java网络编程基础——TCP网络编程三

2022-10-24 11:51:49

AIO实现非阻塞通信

java7 NIO2 提供了异步Channel支持，这种异步Channel可以提供更高效的IO，这种基于异步Channel的IO被称为异步IO(Asynchronous IO)

IO操作分为两步：1、程序发出IO请求  2、完成实际的IO操作

阻塞和非阻塞IO是根据第一步划分的：

发出IO请求如果阻塞线程则是阻塞IO，如果不阻塞线程，则是非阻塞IO。

同步IO和异步IO是根据第二步划分：

如果实际的IO操作是由操作系统完成，再将结果返回给应用程序，这就是异步IO。

如果实际的IO需要应用程序本身去执行，会阻塞线程，那就是同步IO。

(java传统的IO操作和基于Channel的非阻塞IO都是同步IO)

NIO2提供了一系列以Asynchronous开头的Channel接口和类。

其中AsynchronousSocketChannel、AsynchronousServerSocketChannel是支持TCP通信的异步Channel。

AsynchronousServerSocketChannel：负责监听的Channel,与ServerSocketChannel相似。

AsynchronousServerSocketChannel使用需要三步：

1)调用open()静态方法创建AsynchronousServerSocketChannel实例

2)调用AsynchronousServerSocketChannel的bind()方法让他在指定IP，端口监听。

3)调用AsynchronousServerSocketChannel的accept()方法接收连接请求。

AsynchronousSocketChannel：与SocketChannel类似，执行具体的IO操作

AsynchronousSocketChannel的用法也可以分为三步:

1)调用Open()静态方法创建AsynchronousSocketChannel实例

2)调用AsynchronousSocketChannel的connect()方法让他在指定IP，端口服务器。

3)调用AsynchronousSocketChannel的read()、write()方法进行读写。

AsynchronousServerSocketChannel、AsynchronousSocketChannel都允许使用线程池管理，open()方法创建对应实例时都可以传入AsynchronousChannelGroup。AsynchronousChannelGroup创建需要传入一个线程池ExecutorService。

AsynchronousServerSocketChannel的accept()方法、AsynchronousSocketChannel的read()、write()方法都有两个版本

1)返回Future对象版本：必须等到Future的get方法返回时IO操作才完成，get方法会阻塞线程的。

2)需要传入CompletionHandler版本：通过ComplctionHandler完成相关操作。

CompletionHandler是一个接口，该接口中定义了两个方法：

completed(V result,A attachment):当IO操作完成时触发该方法，第一参数表示IO操作返回的参数；第二个参数表示发起IO操作时传入的附加参数。

failed(Trowable exc,A attachment):当IO操作失败事触发该方法，第一参数表示异常信息，，第二个参数表示发起IO操作时传入的附加参数。

下面使用Future对象版本实现简单的AIO服务端、客户端通信：

package net;

import java.io.IOException;

import java.net.InetSocketAddress;

import java.nio.ByteBuffer;

import java.nio.channels.AsynchronousServerSocketChannel;

import java.nio.channels.AsynchronousSocketChannel;

import java.util.concurrent.Future;

public class SimpleAIOServer {

    static final int PORT = 30000;

    public static void main(String[] args) throws Exception {

        try (//创建AsynchronousServerSocketChannel实例

                AsynchronousServerSocketChannel serverSocketChannel =

                    AsynchronousServerSocketChannel.open();)

        {

            serverSocketChannel.bind(new InetSocketAddress(PORT));

            while(true) {

                //采用循环接收客户端的连接

                Future<AsynchronousSocketChannel> future = serverSocketChannel.accept();

                //获取连接后返回AsynchronousSocketChannel

                AsynchronousSocketChannel socketChannel = future.get();

                //向客户端输出数据

                Future<Integer> future1 =socketChannel.write(ByteBuffer.wrap("AIO HELLO".

                getBytes("UTF-8")));

                future1.get();

            }

        } catch (IOException e) {

            e.printStackTrace();

        }

    }

}

package net;

import java.io.IOException;

import java.net.InetSocketAddress;

import java.nio.Buffer;

import java.nio.ByteBuffer;

import java.nio.channels.AsynchronousSocketChannel;

import java.nio.charset.Charset;

import java.util.concurrent.Future;

public class SimpleAIOClient {

    static final int PORT = 30000;

    public static void main(String[] args) throws Exception {

        //用户读取数据的Buffer

        ByteBuffer buff = ByteBuffer.allocate(1024);

        Charset charset = Charset.forName("UTF-8");

        try(//创建AsynchronousSocketChannel实例

            AsynchronousSocketChannel socketChannel = AsynchronousSocketChannel.open();)

        {

            //连接到远程服务器

            Future<Void> future = socketChannel.connect(new InetSocketAddress("127.0.0.1", PORT));

            future.get();

            buff.clear();

            //socketChannel中读取数据

            Future<Integer> future1 = socketChannel.read(buff);

            future1.get();

            buff.flip();

            String content = charset.decode(buff).toString();

            System.out.println("服务器：" + content);

        } catch (IOException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }

    }

}

结果：

服务器：AIO HELLO

AIO实现多人聊天

package net;

import java.io.IOException;

import java.net.InetSocketAddress;

import java.nio.channels.AsynchronousChannelGroup;

import java.nio.channels.AsynchronousServerSocketChannel;

import java.nio.channels.AsynchronousSocketChannel;

import java.util.ArrayList;

import java.util.List;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

public class AIOServer {

    static final int PORT = 30000;

    static List<AsynchronousSocketChannel> channelList = new ArrayList<>();

    public void init() throws IOException {

        //创建一个线程池

        ExecutorService executor = Executors.newFixedThreadPool(20);

        //以指定线程池创建分组管理器

        AsynchronousChannelGroup channelGroup = AsynchronousChannelGroup.withThreadPool(executor);

        //以线程池创建AsynchronousServerSocketChannel

        AsynchronousServerSocketChannel serverSocketChannel =

                                AsynchronousServerSocketChannel.open(channelGroup);

        //绑定端口

        serverSocketChannel.bind(new InetSocketAddress(PORT));

        //使用CompletionHandler处理客户端连接请求，此处的Handler主要处理客户端连接请求

        serverSocketChannel.accept(null, new AcceptHandler(serverSocketChannel));

    }

    public static void main(String[] args) throws Exception {

        AIOServer aioServer = new AIOServer();

        aioServer.init();

        Thread.sleep(Integer.MAX_VALUE);

         //不让服务器停止

        while(true) {}

    }

}
package net;

import java.nio.ByteBuffer;

import java.nio.channels.AsynchronousServerSocketChannel;

import java.nio.channels.AsynchronousSocketChannel;

import java.nio.channels.CompletionHandler;

import java.nio.charset.Charset;

import java.util.concurrent.ExecutionException;

public class AcceptHandler implements CompletionHandler<AsynchronousSocketChannel, Object>{

    private AsynchronousServerSocketChannel serverSocketChannel = null;

    public AcceptHandler(AsynchronousServerSocketChannel serverSocketChannel) {

        this.serverSocketChannel = serverSocketChannel ;

    }

    //定义一个Buffer准备读取数据

    ByteBuffer buff = ByteBuffer.allocate(1024);

    Charset charset = Charset.forName("UTF-8");

    //当IO操作完成时触发该方法

    @Override

    public void completed(final AsynchronousSocketChannel socketChannel, Object attachment) {

        //记录新进来的Channel

        AIOServer.channelList.add(socketChannel);

        //准备接收客户端的下一次连接

        serverSocketChannel.accept(null, this);

        //读取客户端数据，此处的Handler主要处理读取客户数据

        socketChannel.read(buff, null, new CompletionHandler<Integer, Object>() {

            @Override

            public void completed(Integer result, Object attachment) {

                buff.flip();

                //将Buffer中的数据转换成字符串

                String content = charset.decode(buff).toString();

                //将客户端发来的数据 发送到么每个客户端

                for(AsynchronousSocketChannel asc : AIOServer.channelList) {

                    try {

                        asc.write(ByteBuffer.wrap(content.getBytes(charset))).get();

                    } catch (InterruptedException | ExecutionException e) {

                        e.printStackTrace();

                    }

                }

                //清空buff容器，用户读取下一次数据

                buff.clear();

            }

            //当IO操作失败事触发该方法

            @Override

            public void failed(Throwable exc, Object attachment) {

                System.out.println("读取数据失败："+ exc);

                //读取数据失败，客户端出问题，移除对应的channel

                AIOServer.channelList.remove(socketChannel);

            }

        });

    }

    @Override

    public void failed(Throwable exc, Object attachment) {

        System.out.println("连接失败:"+exc);

    }

}
package net;

import java.awt.BorderLayout;

import java.awt.event.ActionEvent;

import java.awt.event.InputEvent;

import java.net.InetSocketAddress;

import java.nio.ByteBuffer;

import java.nio.channels.AsynchronousChannelGroup;

import java.nio.channels.AsynchronousSocketChannel;

import java.nio.channels.CompletionHandler;

import java.nio.charset.StandardCharsets;

import java.util.concurrent.ExecutionException;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import javax.swing.AbstractAction;

import javax.swing.Action;

import javax.swing.JButton;

import javax.swing.JFrame;

import javax.swing.JPanel;

import javax.swing.JScrollPane;

import javax.swing.JTextArea;

import javax.swing.JTextField;

import javax.swing.KeyStroke;

public class AIOClient {

    static final int PORT = 30000;

    //与服务器通信的异步Channel

    AsynchronousSocketChannel socketChannel = null;

    JFrame mainWin = new JFrame("多人聊天");

    JTextArea jta = new JTextArea(16,48);

    JTextField jtf = new JTextField(40);

    JButton sendBtn = new JButton("发送");

    public void init() {

        mainWin.setLayout(new BorderLayout());

        jta.setEditable(false);

        mainWin.add(new JScrollPane(jta),BorderLayout.CENTER);

        JPanel jp = new JPanel();

        jp.add(jtf);

        jp.add(sendBtn);

        @SuppressWarnings("serial")

        Action sendAction  = new AbstractAction() {

            @Override

            public void actionPerformed(ActionEvent e) {

                String content = jtf.getText();

                if(content.trim().length() > 0) {

                    //将输入内容写到channel中

                    try {

                        socketChannel.write(ByteBuffer.

                        wrap(content.getBytes(StandardCharsets.UTF_8))).get();

                    } catch (InterruptedException | ExecutionException e1) {

                        e1.printStackTrace();

                    }

                }

                jtf.setText("");

            }

        };

        sendBtn.addActionListener(sendAction);

        jtf.getInputMap().put(KeyStroke.getKeyStroke('\n', InputEvent.CTRL_MASK), "send");

        jtf.getActionMap().put("send", sendAction);

        mainWin.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        mainWin.add(jp, BorderLayout.SOUTH);

        mainWin.pack();

        mainWin.setVisible(true);

    }

    public void connect() throws Exception {

        //用于读取数据的buffer

        ByteBuffer buff = ByteBuffer.allocate(1024);

        //创建一个线程池

        ExecutorService executor = Executors.newFixedThreadPool(80);

        //以指定线程池创建分组管理器

        AsynchronousChannelGroup channelGroup = AsynchronousChannelGroup.withThreadPool(executor);

        //以分组管理器创建AsynchronousSocketChannel

        socketChannel =  AsynchronousSocketChannel.open(channelGroup);

        //连接服务器

        socketChannel.connect(new InetSocketAddress("127.0.0.1", PORT)).get();

        jta.append("***与服务器连接成功***\n");

        socketChannel.read(buff, null, new CompletionHandler<Integer, Object>() {

            @Override

            public void completed(Integer result, Object attachment) {

                buff.flip();

                //将Buffer转换成字符串

                String content = StandardCharsets.UTF_8.decode(buff).toString();

                //显示从服务器读取的数据

                jta.append("某人说："+content+"\n");

                buff.clear();

                //为下一次读取数据做准备

                socketChannel.read(buff, null, this);

            }

            @Override

            public void failed(Throwable exc, Object attachment) {

                System.out.println("读取数据失败"+exc);

            }

        });

    }

    public static void main(String[] args) throws Exception {

        AIOClient aioClient = new AIOClient();

        aioClient.init();

        aioClient.connect();

    }

}
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package net;
 
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.nio.channels.AsynchronousSocketChannel;
import java.nio.charset.Charset;
import java.util.concurrent.Future;
 
public class SimpleAIOClient {
 
    static final int PORT = 30000;
     
    public static void main(String[] args) throws Exception {
         
        //用户读取数据的Buffer
        ByteBuffer buff = ByteBuffer.allocate(1024);
        Charset charset = Charset.forName("UTF-8");
        try(//创建AsynchronousSocketChannel实例
            AsynchronousSocketChannel socketChannel = AsynchronousSocketChannel.open();)
        {
            //连接到远程服务器
            Future<Void> future = socketChannel.connect(new InetSocketAddress("127.0.0.1", PORT));
            future.get();
             
            buff.clear();
            //socketChannel中读取数据
            Future<Integer> future1 = socketChannel.read(buff);
            future1.get();
             
            buff.flip();
            String content = charset.decode(buff).toString();
            System.out.println("服务器：" + content);
         
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

结果：

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