Java NIO 同步非阻塞应用实例

一、server：

package org.windwant.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;

/**
 * ServerSocketChannel
 */
public class NIOServer {
    /*标识数字*/
    private int flag = 0;
    /*缓冲区大小*/
    private int BLOCK = 2048;
    /*接受数据缓冲区*/
    private ByteBuffer sendbuffer = ByteBuffer.allocate(BLOCK);
    /*发送数据缓冲区*/
    private ByteBuffer receivebuffer = ByteBuffer.allocate(BLOCK);
    private Selector selector;

    public NIOServer(int port) throws IOException {
        // 打开服务器套接字通道

        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        // 服务器配置为非阻塞

        serverSocketChannel.configureBlocking(false);
        // 检索与此通道关联的服务器套接字

        ServerSocket serverSocket = serverSocketChannel.socket();
        // 进行服务的绑定

        serverSocket.bind(new InetSocketAddress(port));
        // 通过open()方法找到Selector

        selector = Selector.open();
        // 注册到selector，等待连接

        serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
        System.out.println("Server Start----8888:");
    }


    // 监听

    private void listen() throws IOException {
        while (true) {
            // 选择一组键，并且相应的通道已经打开

            selector.select();
            // 返回此选择器的已选择键集。

            Set<SelectionKey> selectionKeys = selector.selectedKeys();
            Iterator<SelectionKey> iterator = selectionKeys.iterator();
            while (iterator.hasNext()) {
                SelectionKey selectionKey = iterator.next();
                iterator.remove();
                handleKey(selectionKey);
            }
        }
    }

    // 处理请求

    private void handleKey(SelectionKey selectionKey) throws IOException {
        // 接受请求

        ServerSocketChannel server = null;
        SocketChannel client = null;
        String receiveText;
        String sendText;
        int count=0;
        // 测试此键的通道是否已准备好接受新的套接字连接。

        if (selectionKey.isAcceptable()) {
            // 返回为之创建此键的通道。

            server = (ServerSocketChannel) selectionKey.channel();
            // 接受到此通道套接字的连接。

            // 此方法返回的套接字通道（如果有）将处于阻塞模式。

            client = server.accept();
            // 配置为非阻塞

            client.configureBlocking(false);
            // 注册到selector，等待连接

            client.register(selector, SelectionKey.OP_READ);
        } else if (selectionKey.isReadable()) {
            // 返回为之创建此键的通道。

            client = (SocketChannel) selectionKey.channel();
            //将缓冲区清空以备下次读取

            receivebuffer.clear();
            //读取服务器发送来的数据到缓冲区中

            count = client.read(receivebuffer);
            if (count > 0) {
                receiveText = new String( receivebuffer.array(),0,count);
                System.out.println("服务器端接受客户端数据--:"+receiveText);
                client.register(selector, SelectionKey.OP_WRITE);
            }
        } else if (selectionKey.isWritable()) {
            //将缓冲区清空以备下次写入

            sendbuffer.clear();
            // 返回为之创建此键的通道。

            client = (SocketChannel) selectionKey.channel();


            sendText = "<h1>message from server: this is the test message!</h1>";

//            sendText="message from server--" + flag++;
            //向缓冲区中输入数据

            sendbuffer.put(sendText.getBytes());
            //将缓冲区各标志复位,因为向里面put了数据标志被改变要想从中读取数据发向服务器,就要复位

            sendbuffer.flip();
            //输出到通道

            client.write(sendbuffer);
            System.out.println("服务器端向客户端发送数据--："+sendText);
            client.register(selector, SelectionKey.OP_READ);
        }
    }

    /**
     * @param args
     * @throws IOException
     */
    public static void main(String[] args) throws IOException {
        int port = 8888;
        NIOServer server = new NIOServer(port);
        server.listen();
    }
}

二、client：

package org.windwant.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;

/**
 * SocketChannel
 */
public class NIOClient {
    /*标识数字*/
    private static int flag = 0;
    /*缓冲区大小*/
    private static int BLOCK = 4096;
    /*接受数据缓冲区*/
    private static ByteBuffer sendbuffer = ByteBuffer.allocate(BLOCK);
    /*发送数据缓冲区*/
    private static ByteBuffer receivebuffer = ByteBuffer.allocate(BLOCK);
    /*服务器端地址*/
    private final static InetSocketAddress SERVER_ADDRESS = new InetSocketAddress(
            "localhost", 8888);

    public static void main(String[] args) throws IOException {
        // 打开socket通道

        SocketChannel socketChannel = SocketChannel.open();
        // 设置为非阻塞方式

        socketChannel.configureBlocking(false);
        // 打开选择器

        Selector selector = Selector.open();
        // 注册连接服务端socket动作

        socketChannel.register(selector, SelectionKey.OP_CONNECT);
        // 连接

        socketChannel.connect(SERVER_ADDRESS);
        // 分配缓冲区大小内存


        Set<SelectionKey> selectionKeys;
        Iterator<SelectionKey> iterator;
        SelectionKey selectionKey;
        SocketChannel client;
        String receiveText;
        String sendText;
        int count=0;

        while (true) {
            //选择一组键，其相应的通道已为 I/O 操作准备就绪。

            //此方法执行处于阻塞模式的选择操作。

            selector.select();
            //返回此选择器的已选择键集。

            selectionKeys = selector.selectedKeys();
            //System.out.println(selectionKeys.size());

            iterator = selectionKeys.iterator();
            while (iterator.hasNext()) {
                selectionKey = iterator.next();
                if (selectionKey.isConnectable()) {
                    System.out.println("client connect");
                    client = (SocketChannel) selectionKey.channel();
                    // 判断此通道上是否正在进行连接操作。

                    // 完成套接字通道的连接过程。

                    if (client.isConnectionPending()) {
                        client.finishConnect();
                        System.out.println("完成连接!");
                        sendbuffer.clear();
                        sendbuffer.put("Hello,Server".getBytes());
                        sendbuffer.flip();
                        client.write(sendbuffer);
                    }
                    client.register(selector, SelectionKey.OP_READ);
                } else if (selectionKey.isReadable()) {
                    client = (SocketChannel) selectionKey.channel();
                    //将缓冲区清空以备下次读取

                    receivebuffer.clear();
                    //读取服务器发送来的数据到缓冲区中

                    count=client.read(receivebuffer);
                    if(count>0){
                        receiveText = new String( receivebuffer.array(),0,count);
                        System.out.println("客户端接受服务器端数据--:"+receiveText);
                        client.register(selector, SelectionKey.OP_WRITE);
                    }

                } else if (selectionKey.isWritable()) {
                    sendbuffer.clear();
                    client = (SocketChannel) selectionKey.channel();
                    sendText = "message from client--" + (flag++);
                    sendbuffer.put(sendText.getBytes());
                    //将缓冲区各标志复位,因为向里面put了数据标志被改变要想从中读取数据发向服务器,就要复位

                    sendbuffer.flip();
                    client.write(sendbuffer);
                    System.out.println("客户端向服务器端发送数据--："+sendText);
                    client.register(selector, SelectionKey.OP_READ);
                }
            }
            selectionKeys.clear();
        }
    }
}

项目地址：https://github.com/windwant/windwant-service/tree/master/io-service