NIOServer

package com.study.hc.net.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;

/**
 * 直接基于非阻塞的写法
 */
public class NIOServer {

    public static void main(String[] args) throws Exception {
        // 创建网络服务端
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        serverSocketChannel.configureBlocking(false); // 设置为非阻塞模式
        serverSocketChannel.socket().bind(new InetSocketAddress(8080)); // 绑定端口
        System.out.println("启动成功");
        while (true) {
            SocketChannel socketChannel = serverSocketChannel.accept(); // 获取新tcp连接通道
            // tcp请求 读取/响应
            if (socketChannel != null) {
                System.out.println("收到新连接 : " + socketChannel.getRemoteAddress());
                socketChannel.configureBlocking(false); // 默认是阻塞的,一定要设置为非阻塞
                try {
                    ByteBuffer requestBuffer = ByteBuffer.allocate(1024);
                    while (socketChannel.isOpen() && socketChannel.read(requestBuffer) != -1) {
                        // 长连接情况下,需要手动判断数据有没有读取结束 (此处做一个简单的判断: 超过0字节就认为请求结束了)
                        if (requestBuffer.position() > 0) break;
                    }
                    if(requestBuffer.position() == 0) continue; // 如果没数据了, 则不继续后面的处理
                    requestBuffer.flip();
                    byte[] content = new byte[requestBuffer.limit()];
                    requestBuffer.get(content);
                    System.out.println(new String(content));
                    System.out.println("收到数据,来自："+ socketChannel.getRemoteAddress());

                    // 响应结果 200
                    String response = "HTTP/1.1 200 OK\r\n" +
                            "Content-Length: 11\r\n\r\n" +
                            "Hello World";
                    ByteBuffer buffer = ByteBuffer.wrap(response.getBytes());
                    while (buffer.hasRemaining()) {
                        socketChannel.write(buffer);// 非阻塞
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        // 用到了非阻塞的API, 在设计上,和BIO可以有很大的不同.继续改进
    }
}

package com.study.hc.net.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.ArrayList;
import java.util.Iterator;

/**
 * 直接基于非阻塞的写法,一个线程处理轮询所有请求
 */
public class NIOServer1 {
    /**
     * 已经建立连接的集合
     */
    private static ArrayList<SocketChannel> channels = new ArrayList<>();

    public static void main(String[] args) throws Exception {
        // 创建网络服务端
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        serverSocketChannel.configureBlocking(false); // 设置为非阻塞模式
        serverSocketChannel.socket().bind(new InetSocketAddress(8080)); // 绑定端口
        System.out.println("启动成功");
        while (true) {
            SocketChannel socketChannel = serverSocketChannel.accept(); // 获取新tcp连接通道
                // tcp请求 读取/响应
                if (socketChannel != null) {
                System.out.println("收到新连接 : " + socketChannel.getRemoteAddress());
                socketChannel.configureBlocking(false); // 默认是阻塞的,一定要设置为非阻塞
                channels.add(socketChannel);
            } else {
                // 没有新连接的情况下,就去处理现有连接的数据,处理完的就删除掉
                Iterator<SocketChannel> iterator = channels.iterator();
                while (iterator.hasNext()) {
                    SocketChannel ch = iterator.next();
                    try {
                        ByteBuffer requestBuffer = ByteBuffer.allocate(1024);

                        if (ch.read(requestBuffer) == 0) {
                            // 等于0,代表这个通道没有数据需要处理,那就待会再处理
                            continue;
                        }
                        while (ch.isOpen() && ch.read(requestBuffer) != -1) {
                            // 长连接情况下,需要手动判断数据有没有读取结束 (此处做一个简单的判断: 超过0字节就认为请求结束了)
                            if (requestBuffer.position() > 0) break;
                        }
                        if(requestBuffer.position() == 0) continue; // 如果没数据了, 则不继续后面的处理
                        requestBuffer.flip();
                        byte[] content = new byte[requestBuffer.limit()];
                        requestBuffer.get(content);
                        System.out.println(new String(content));
                        System.out.println("收到数据,来自：" + ch.getRemoteAddress());

                        // 响应结果 200
                        String response = "HTTP/1.1 200 OK\r\n" +
                                "Content-Length: 11\r\n\r\n" +
                                "Hello World";
                        ByteBuffer buffer = ByteBuffer.wrap(response.getBytes());
                        while (buffer.hasRemaining()) {
                            ch.write(buffer);
                        }
                        iterator.remove();
                    } catch (IOException e) {
                        e.printStackTrace();
                        iterator.remove();
                    }
                }
            }
        }
        // 用到了非阻塞的API, 再设计上,和BIO可以有很大的不同
        // 问题: 轮询通道的方式,低效,浪费CPU
    }
}

package com.study.hc.net.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.Iterator;
import java.util.Set;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * 结合Selector实现的非阻塞服务端(放弃对channel的轮询,借助消息通知机制)
 */
public class NIOServerV2 {

    public static void main(String[] args) throws Exception {
        // 1. 创建网络服务端ServerSocketChannel
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        serverSocketChannel.configureBlocking(false); // 设置为非阻塞模式

        // 2. 构建一个Selector选择器,并且将channel注册上去
        Selector selector = Selector.open();
        SelectionKey selectionKey = serverSocketChannel.register(selector, 0, serverSocketChannel);// 将serverSocketChannel注册到selector
        selectionKey.interestOps(SelectionKey.OP_ACCEPT); // 对serverSocketChannel上面的accept事件感兴趣(serverSocketChannel只能支持accept操作)

        // 3. 绑定端口
        serverSocketChannel.socket().bind(new InetSocketAddress(8080));

        System.out.println("启动成功");

        while (true) {
            // 不再轮询通道,改用下面轮询事件的方式.select方法有阻塞效果,直到有事件通知才会有返回
            selector.select();
            // 获取事件
            Set<SelectionKey> selectionKeys = selector.selectedKeys();
            // 遍历查询结果e
            Iterator<SelectionKey> iter = selectionKeys.iterator();
            while (iter.hasNext()) {
                // 被封装的查询结果
                SelectionKey key = iter.next();
                iter.remove();
                // 关注 Read 和 Accept两个事件
                if (key.isAcceptable()) {
                    ServerSocketChannel server = (ServerSocketChannel) key.attachment();
                    // 将拿到的客户端连接通道,注册到selector上面
                    SocketChannel clientSocketChannel = server.accept(); // mainReactor 轮询accept
                    clientSocketChannel.configureBlocking(false);
                    clientSocketChannel.register(selector, SelectionKey.OP_READ, clientSocketChannel);
                    System.out.println("收到新连接 : " + clientSocketChannel.getRemoteAddress());
                }

                if (key.isReadable()) {
                    SocketChannel socketChannel = (SocketChannel) key.attachment();
                    try {
                        ByteBuffer requestBuffer = ByteBuffer.allocate(1024);
                        while (socketChannel.isOpen() && socketChannel.read(requestBuffer) != -1) {
                            // 长连接情况下,需要手动判断数据有没有读取结束 (此处做一个简单的判断: 超过0字节就认为请求结束了)
                            if (requestBuffer.position() > 0) break;
                        }
                        if(requestBuffer.position() == 0) continue; // 如果没数据了, 则不继续后面的处理
                        requestBuffer.flip();
                        byte[] content = new byte[requestBuffer.limit()];
                        requestBuffer.get(content);
                        System.out.println(new String(content));
                        System.out.println("收到数据,来自：" + socketChannel.getRemoteAddress());
                        // TODO 业务操作 数据库 接口调用等等

                        // 响应结果 200
                        String response = "HTTP/1.1 200 OK\r\n" +
                                "Content-Length: 11\r\n\r\n" +
                                "Hello World";
                        ByteBuffer buffer = ByteBuffer.wrap(response.getBytes());
                        while (buffer.hasRemaining()) {
                            socketChannel.write(buffer);
                        }
                    } catch (IOException e) {
                        // e.printStackTrace();
                        key.cancel(); // 取消事件订阅
                    }
                }
            }
            selector.selectNow();
        }
        // 问题: 此处一个selector监听所有事件,一个线程处理所有请求事件. 会成为瓶颈! 要有多线程的运用
    }
}

package com.study.hc.net.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.Iterator;
import java.util.Random;
import java.util.Set;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.FutureTask;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * NIO selector 多路复用reactor线程模型
 */
public class NIOServerV3 {
    /** 处理业务操作的线程 */
    private static ExecutorService workPool = Executors.newCachedThreadPool();

    /**
     * 封装了selector.select()等事件轮询的代码
     */
    abstract class ReactorThread extends Thread {

        Selector selector;
        LinkedBlockingQueue<Runnable> taskQueue = new LinkedBlockingQueue<>();

        /**
         * Selector监听到有事件后,调用这个方法
         */
        public abstract void handler(SelectableChannel channel) throws Exception;

        private ReactorThread() throws IOException {
            selector = Selector.open();
        }

        volatile boolean running = false;

        @Override
        public void run() {
            // 轮询Selector事件
            while (running) {
                try {
                    // 执行队列中的任务
                    Runnable task;
                    while ((task = taskQueue.poll()) != null) {
                        task.run();
                    }
                    selector.select(1000);

                    // 获取查询结果
                    Set<SelectionKey> selected = selector.selectedKeys();
                    // 遍历查询结果
                    Iterator<SelectionKey> iter = selected.iterator();
                    while (iter.hasNext()) {
                        // 被封装的查询结果
                        SelectionKey key = iter.next();
                        iter.remove();
                        int readyOps = key.readyOps();
                        // 关注 Read 和 Accept两个事件
                        if ((readyOps & (SelectionKey.OP_READ | SelectionKey.OP_ACCEPT)) != 0 || readyOps == 0) {
                            try {
                                SelectableChannel channel = (SelectableChannel) key.attachment();
                                channel.configureBlocking(false);
                                handler(channel);
                                if (!channel.isOpen()) {
                                    key.cancel(); // 如果关闭了,就取消这个KEY的订阅
                                }
                            } catch (Exception ex) {
                                key.cancel(); // 如果有异常,就取消这个KEY的订阅
                            }
                        }
                    }
                    selector.selectNow();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

        private SelectionKey register(SelectableChannel channel) throws Exception {
            // 为什么register要以任务提交的形式，让reactor线程去处理？
            // 因为线程在执行channel注册到selector的过程中，会和调用selector.select()方法的线程争用同一把锁
            // 而select()方法实在eventLoop中通过while循环调用的，争抢的可能性很高，为了让register能更快的执行，就放到同一个线程来处理
            FutureTask<SelectionKey> futureTask = new FutureTask<>(() -> channel.register(selector, 0, channel));
            taskQueue.add(futureTask);
            return futureTask.get();
        }

        private void doStart() {
            if (!running) {
                running = true;
                start();
            }
        }
    }

    private ServerSocketChannel serverSocketChannel;
    // 1、创建多个线程 - accept处理reactor线程 (accept线程)
    private ReactorThread[] mainReactorThreads = new ReactorThread[1];
    // 2、创建多个线程 - io处理reactor线程  (I/O线程)
    private ReactorThread[] subReactorThreads = new ReactorThread[8];

    /**
     * 初始化线程组
     */
    private void newGroup() throws IOException {
        // 创建IO线程,负责处理客户端连接以后socketChannel的IO读写
        for (int i = 0; i < subReactorThreads.length; i++) {
            subReactorThreads[i] = new ReactorThread() {
                @Override
                public void handler(SelectableChannel channel) throws IOException {
                    // work线程只负责处理IO处理，不处理accept事件
                    SocketChannel ch = (SocketChannel) channel;
                    ByteBuffer requestBuffer = ByteBuffer.allocate(1024);
                    while (ch.isOpen() && ch.read(requestBuffer) != -1) {
                        // 长连接情况下,需要手动判断数据有没有读取结束 (此处做一个简单的判断: 超过0字节就认为请求结束了)
                        if (requestBuffer.position() > 0) break;
                    }
                    if (requestBuffer.position() == 0) return; // 如果没数据了, 则不继续后面的处理
                    requestBuffer.flip();
                    byte[] content = new byte[requestBuffer.limit()];
                    requestBuffer.get(content);
                    System.out.println(new String(content));
                    System.out.println(Thread.currentThread().getName() + "收到数据,来自：" + ch.getRemoteAddress());

                    // TODO 业务操作 数据库、接口...
                    workPool.submit(() -> {
                    });

                    // 响应结果 200
                    String response = "HTTP/1.1 200 OK\r\n" +
                            "Content-Length: 11\r\n\r\n" +
                            "Hello World";
                    ByteBuffer buffer = ByteBuffer.wrap(response.getBytes());
                    while (buffer.hasRemaining()) {
                        ch.write(buffer);
                    }
                }
            };
        }

        // 创建mainReactor线程, 只负责处理serverSocketChannel
        for (int i = 0; i < mainReactorThreads.length; i++) {
            mainReactorThreads[i] = new ReactorThread() {
                AtomicInteger incr = new AtomicInteger(0);

                @Override
                public void handler(SelectableChannel channel) throws Exception {
                    // 只做请求分发，不做具体的数据读取
                    ServerSocketChannel ch = (ServerSocketChannel) channel;
                    SocketChannel socketChannel = ch.accept();
                    socketChannel.configureBlocking(false);
                    // 收到连接建立的通知之后，分发给I/O线程继续去读取数据
                    int index = incr.getAndIncrement() % subReactorThreads.length;
                    ReactorThread workEventLoop = subReactorThreads[index];
                    workEventLoop.doStart();
                    SelectionKey selectionKey = workEventLoop.register(socketChannel);
                    selectionKey.interestOps(SelectionKey.OP_READ);
                    System.out.println(Thread.currentThread().getName() + "收到新连接 : " + socketChannel.getRemoteAddress());
                }
            };
        }


    }

    /**
     * 初始化channel,并且绑定一个eventLoop线程
     *
     * @throws IOException IO异常
     */
    private void initAndRegister() throws Exception {
        // 1、 创建ServerSocketChannel
        serverSocketChannel = ServerSocketChannel.open();
        serverSocketChannel.configureBlocking(false);
        // 2、 将serverSocketChannel注册到selector
        int index = new Random().nextInt(mainReactorThreads.length);
        mainReactorThreads[index].doStart();
        SelectionKey selectionKey = mainReactorThreads[index].register(serverSocketChannel);
        selectionKey.interestOps(SelectionKey.OP_ACCEPT);
    }

    /**
     * 绑定端口
     *
     * @throws IOException IO异常
     */
    private void bind() throws IOException {
        //  1、 正式绑定端口，对外服务
        serverSocketChannel.bind(new InetSocketAddress(8080));
        System.out.println("启动完成，端口8080");
    }

    public static void main(String[] args) throws Exception {
        NIOServerV3 nioServerV3 = new NIOServerV3();
        nioServerV3.newGroup(); // 1、 创建main和sub两组线程
        nioServerV3.initAndRegister(); // 2、 创建serverSocketChannel，注册到mainReactor线程上的selector上
        nioServerV3.bind(); // 3、 为serverSocketChannel绑定端口
    }
}

package com.study.hc.net.nio;

import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;
import java.util.Scanner;

public class NIOClient {

    public static void main(String[] args) throws Exception {
        SocketChannel socketChannel = SocketChannel.open();
        socketChannel.configureBlocking(false);
        socketChannel.connect(new InetSocketAddress("127.0.0.1", 8080));
        while (!socketChannel.finishConnect()) {
            // 没连接上,则一直等待
            Thread.yield();
        }
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入：");
        // 发送内容
        String msg = scanner.nextLine();
        ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
        while (buffer.hasRemaining()) {
            socketChannel.write(buffer);
        }
        // 读取响应
        System.out.println("收到服务端响应:");
        ByteBuffer requestBuffer = ByteBuffer.allocate(1024);

        while (socketChannel.isOpen() && socketChannel.read(requestBuffer) != -1) {
            // 长连接情况下,需要手动判断数据有没有读取结束 (此处做一个简单的判断: 超过0字节就认为请求结束了)
            if (requestBuffer.position() > 0) break;
        }
        requestBuffer.flip();
        byte[] content = new byte[requestBuffer.limit()];
        requestBuffer.get(content);
        System.out.println(new String(content));
        scanner.close();
        socketChannel.close();
    }

}