二、基於BIO、僞異步IO、NIO的Java代碼實例

1、BIO代碼實例

服務端：

package BIODemo;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;

/**
 * Created by L_kanglin on 2017/5/11.
 */
public class TimeServer {
    public static void main(String[] args) throws IOException {
        int port=9030;
        if(args !=null && args.length >0){
            port=Integer.valueOf(args[0]);
        }
        ServerSocket server=null;
        try{
            server= new ServerSocket(port);
            System.out.println("The time server is start in port: "+port);
            Socket socket=null;
            while(true){
                //當沒有客戶端連接時，程序會阻塞在accept這裏，當有客戶端訪問時，就會創建新的線程去重新執行。
                socket=server.accept();
                //每有一個客戶端訪問，就添加一個線程執行
                new Thread(new TimeServerHandler(socket)).start();
            }
        }finally{
            if(server !=null){
                System.out.println("The time server close");
                server.close();
                server=null;
            }
        }
    }
}

package BIODemo;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Scanner;

/**
 * Created by L_kanglin on 2017/5/12.
 */
public class TimeServerHandler implements Runnable {
    private Socket socket;
    public TimeServerHandler(Socket socket) {
        this.socket=socket;
    }

    @Override
    public void run() {
        BufferedReader in=null;
        PrintWriter out=null;
        try {
            //獲取輸入流
            in= new BufferedReader(new InputStreamReader(this.socket.getInputStream()));
            //構造輸出流
            out= new PrintWriter(this.socket.getOutputStream(),true);

            String currentTime=null;
            String body=null;
            Scanner sc= new Scanner(System.in);
            while(true){
                while(sc.hasNext()){
                    body=in.readLine();
                    if(body==null){break;}
                    System.out.println("server receive : "+body);
                    String str=sc.nextLine();
                    out.println(str);
                //    System.out.println("the server send: "+str);
                }
                /*currentTime="QUERY TIME ORDER".equalsIgnoreCase(body)?new java.util.Date
                        (System.currentTimeMillis()).toString():"BAD ORDER";
                out.println(currentTime);*/
            }
        } catch(Exception e){
            if(in != null){
                try{
                    in.close();
                }catch (IOException el) {
                    el.printStackTrace();
                }
            }
            if(out !=null){
                out.close();
                out=null;
            }
            if(this.socket !=null){
                try {
                    this.socket.close();
                } catch (IOException e1) {
                    e1.printStackTrace();
                }
                this.socket=null;
            }
        }

    }
}

客戶端：

package BIODemo;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.nio.Buffer;

/**
 * Created by L_kanglin on 2017/5/12.
 */
public class TimeClient {
    public static void main(String[] args) throws IOException {
        int port = 9030;
        if(args !=null && args.length>0){
            port =Integer.valueOf(args[0]);
        }
        Socket socket = null;
        BufferedReader in =null;
        PrintWriter out=null;
        while(true){
            socket = new Socket("127.0.0.1",port);
            in= new BufferedReader(new InputStreamReader(socket.getInputStream()));
            out = new PrintWriter(socket.getOutputStream(),true);
            out.println("QUERY TIME ORDER"); //輸出給服務端
            System.out.println("Send order 2 server succeed.");
            String resp=in.readLine();  //獲取輸入流
            System.out.println("NOW is: "+resp);
        }

         /*catch (Exception e) {
        }finally{

            //client自行依次關閉in、out和socket，否則會造成內存泄漏
            if(out!=null){
                out.close();
                out=null;
            }
            if(in !=null){
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                in = null;
            }
            if(socket !=null){
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                socket=null;
            }
        }*/
    }
}

2、僞異步IO

服務端：

package BBIODemo;

import BIODemo.TimeServerHandler;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;

/**
 * Created by L_kanglin on 2017/5/12.
 * @description 首先創建一個時間服務器處理類的線程池，當接收到新的客戶端連接的時候，
 * 將請求socket封裝成一個Task，然後調用線程池的execute方法執行，從而避免了每個請求接
 * 入都創建一個新的線程。
 */
public class TimeServer {
    public static void main(String[] args) throws IOException {
        int port=9030;
        if(args !=null && args.length >0){
            port=Integer.valueOf(args[0]);
        }
        ServerSocket server=null;
        try {
            server = new ServerSocket(port);
            System.out.println("The time server is start in port: "+port);
            Socket socket = null;

            TimeServerHandlerExecutePool singleExecutor = new TimeServerHandlerExecutePool
                    (50,10000);  //創建IO任務線程池
            while(true){
                socket = server.accept();
                //由於線程池和消息隊列都是有界的，因此，無論客戶端併發連接數多大，它都不會
                //導致線程個數過於膨脹或者內存溢出，相比於傳統的一連接一線程模型，是一種改良
                singleExecutor.execute(new TimeServerHandler(socket));
            }
        } finally{
            if(server !=null){
                System.out.println("The time server close");
                server.close();
                server=null;
            }
        }
    }

}

package BBIODemo;


import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

/**
 * Created by L_kanglin on 2017/5/12.
 */
public class TimeServerHandlerExecutePool {
    private ExecutorService executor;
    public TimeServerHandlerExecutePool(int maxPoolSize,int queueSize){
        executor = new ThreadPoolExecutor(Runtime.getRuntime().availableProcessors()
                ,maxPoolSize,120L,
                TimeUnit.SECONDS,new ArrayBlockingQueue<Runnable>(queueSize));
    }
    public void execute(Runnable task){
        executor.execute(task);
    }
}

客戶端：

package BBIODemo;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;

/**
 * Created by L_kanglin on 2017/5/12.
 * 客戶端通過socket創建，發送查詢時間服務器的“QUERY TIME ORDER”指令，然後
 * 讀取服務端的響應並將結果打印出來，隨後關閉連接，釋放資源，程序退出執行。
 */
public class TimeClient {
    public static void main(String[] args) throws IOException {
        int port = 9030;
        if(args !=null && args.length>0){
            port =Integer.valueOf(args[0]);
        }
        Socket socket = null;
        BufferedReader in =null;
        PrintWriter out=null;
        try{
            socket = new Socket("127.0.0.1",port);
            in= new BufferedReader(new InputStreamReader(socket.getInputStream()));
            out = new PrintWriter(socket.getOutputStream(),true);
            out.println("QUERY TIME ORDER"); //輸出給服務端

            System.out.println("Send order 2 server succeed.");
            String resp=in.readLine();  //獲取輸入流
            System.out.println("NOW is: "+resp);
        } catch (Exception e) {
        }finally{
            if(out!=null){
                out.close();
                out=null;
            }
            if(in !=null){
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                in = null;
            }
            if(socket !=null){
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                socket=null;
            }
        }
    }
}

3、NIO代碼實例

服務端：

package NIODemo;

/**
 * Created by L_kanglin on 2017/5/13.
 */
public class TimeServer {
    public static void main(String[] args) {
        int port=9030;
        if (args !=null && args.length>0){
            port=Integer.valueOf(args[0]);
        }
        MultiplexerTimeServer timeServer = new MultiplexerTimeServer(port);
        //創建Reactor線程，並啓動線程
        new Thread(timeServer,"NIO-MultiplexerTimerServer-001").start();
    }
}

package NIODemo;

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.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;

/**
 * Created by L_kanglin on 2017/5/13.
 */
public class MultiplexerTimeServer implements Runnable {
    private Selector selector;
    private ServerSocketChannel servChannel;
    private volatile boolean stop;
    //初始化多路複用器、綁定監聽端口
    public MultiplexerTimeServer(int port){
        try {
            //創建多路複用器，並開啓
            selector = Selector.open();
            //打開ServerSocketChannel,用於監聽客戶端的連接，它是所有客戶端連接
            //的父管道
            servChannel = ServerSocketChannel.open();
            //綁定監聽端口，設置連接爲非阻塞模式
            servChannel.configureBlocking(false);
            servChannel.socket().bind(new InetSocketAddress(port),1024);
            //將ServerSocketChannel註冊到Reactor線程的多路複用器Selector上，
            //監聽ACCEPT事件
            servChannel.register(selector, SelectionKey.OP_ACCEPT);
            System.out.println("The time server is start in port: "+port);
        } catch (IOException e) {
            e.printStackTrace();
            System.exit(1);
        }
    }
    public void stop(){
        this.stop=true;
    }

    @Override
    public void run() {
        while(!stop){
            try {
                //多路複用器在線程run方法的無限循環體內輪詢準備就緒的Key
                selector.select(1000);
                Set<SelectionKey> selectionKeys = selector.selectedKeys();
                Iterator<SelectionKey> it=selectionKeys.iterator();
                SelectionKey key=null;
                while(it.hasNext()){
                    key=it.next();
                    it.remove();
                    try{
                        handleInput(key);
                    }catch(Exception e){
                        if(key !=null){
                            key.cancel();
                            if(key.channel()!=null){
                                key.channel().close();
                            }
                        }
                    }

                }
            } catch (Throwable t) {
                t.printStackTrace();
            }

        }
        //多路複用器關閉後，所有註冊在上面的Channel和
        // Pipe等資源都會被自動去註冊並關閉，所以不需
        // 要重複釋放資源
        if(selector !=null)
            try{
                selector.close();
            }catch(IOException e){
                e.printStackTrace();
            }
    }

    private void handleInput(SelectionKey key) throws IOException {
        if (key.isValid()){
            //處理新接入的請求消息
            ServerSocketChannel ssc= (ServerSocketChannel) key.channel();
            //多路複用器監聽到有新的客戶端接入，處理新的接入請求，
            //完成TCP三次握手，建立物理鏈路
            SocketChannel sc= ssc.accept();
            //設置客戶端鏈路爲非阻塞模式
            sc.configureBlocking(false);
            //將新接入的客戶端連接註冊到Reactor線程的多路複用器上，監聽讀操作，
            //用來讀取客戶端發送的網絡消息
            sc.register(selector,SelectionKey.OP_READ);
        }

        if(key.isReadable()){
            //read the data
            SocketChannel sc= (SocketChannel) key.channel();
            ByteBuffer readBuffer = ByteBuffer.allocate(1024);
            //異步讀取客戶端請求消息到緩衝區
            int readBytes = sc.read(readBuffer);
            if(readBytes>0){
                readBuffer.flip();
                byte[] bytes=new byte[readBuffer.remaining()];
                readBuffer.get(bytes);
                String body=new String(bytes,"UTF-8");
                System.out.println("the time server receive order: "+body);
                String currentTime ="QUERY TIME ORDER".equalsIgnoreCase(body)? new java.
                        util.Date(System.currentTimeMillis()).toString():"BAD ORDER";
                doWrite(sc,currentTime);
            }else if(readBytes<0){
                //對端鏈路關閉
                key.cancel();
                sc.close();
            }else{
                ; //讀到0字節，忽略
            }
        }
    }

    private void doWrite(SocketChannel channel, String response) throws IOException {
        if(response!=null && response.trim().length() >0){
            byte[] bytes = response.getBytes();
            ByteBuffer writeBuffer = ByteBuffer.allocate(bytes.length);
            writeBuffer.put(bytes);
            writeBuffer.flip();
            channel.write(writeBuffer);
        }
    }
}

客戶端：

package NIODemo;

import BIODemo.TimeServerHandler;

import java.io.IOException;

/**
 * Created by L_kanglin on 2017/5/15.
 */
public class TimeClient {
    public static void main(String[] args) throws IOException {
        int port = 9030;
        if (args != null && args.length > 0) {
            port = Integer.valueOf(args[0]);
        }
        new Thread(new TimeClientHandle("127.0.0.1",port),"TimeClient-001").start();

    }
}

package NIODemo;



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;

/**
 * Created by L_kanglin on 2017/5/15.
 */
public class TimeClientHandle implements Runnable {
    private String host;
    private int port;
    private Selector selector;
    private SocketChannel socketChannel;
    private volatile boolean stop;

    public TimeClientHandle(String host,int port){
        this.host =host==null?"127.0.0.1":host;
        this.port=port;
        try {
            selector=Selector.open();
            socketChannel = SocketChannel.open();
            socketChannel.configureBlocking(false);
        } catch (IOException e) {
            e.printStackTrace();
            System.exit(1);
        }
    }

    @Override
    public void run() {

        try {
            doConnect();
        } catch (IOException e) {
            e.printStackTrace();
            System.exit(1);
        }
        while(!stop){
            try {
                selector.select(1000);
                Set<SelectionKey> selectedkeys = selector.selectedKeys();
                Iterator<SelectionKey> it =selectedkeys.iterator();
                SelectionKey key=null;
                while(it.hasNext()){
                    key =it.next();
                    it.remove();
                    handleInput(key);
                    if(key !=null){
                        key.cancel();
                        if(key.channel()!=null)
                            key.channel().close();

                    }
                }

            } catch (IOException e) {
                e.printStackTrace();
                System.exit(1);
            }
        }
        //多路複用器關閉後，所有註冊在上面的Channel和Pipe等資源都會被自動去
        //註冊並關閉，所以不需要重複釋放資源
        if(selector !=null){
            try {
                selector.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    private void handleInput(SelectionKey key) throws IOException {
        if(key.isValid()){
            //判斷是否連接成功
            SocketChannel sc = (SocketChannel) key.channel();
            if(key.isConnectable()){
                if(sc.finishConnect()){
                    sc.register(selector,SelectionKey.OP_READ);
                    doWrite(sc);
                }else{
                    System.exit(1);  //連接失敗，進程退出
                }
            }
            if(key.isReadable()){
                ByteBuffer readBuffer = ByteBuffer.allocate(1024);
                int readBytes = sc.read(readBuffer);
                if(readBytes>0){
                    readBuffer.flip();
                    byte[] bytes=new byte[readBuffer.remaining()];
                    readBuffer.get(bytes);
                    String body=new String(bytes,"UTF-8");
                    System.out.println("Now is : "+body);
                    this.stop=true;
                }else if(readBytes<0){
                    //對端鏈路關閉
                    key.cancel();
                    sc.close();
                }else{
                    ; //讀到0字節，忽略
                }
            }
        }
    }

    private void doConnect() throws IOException {
        //如果直接連接成功，則註冊到多路複用器上，發送請求消息，讀應答
        if(socketChannel.connect(new InetSocketAddress(host,port))){
            socketChannel.register(selector, SelectionKey.OP_READ);
            doWrite(socketChannel);
        }else{
            socketChannel.register(selector,SelectionKey.OP_CONNECT);
        }
    }

    private void doWrite(SocketChannel sc) throws IOException {
        byte[] req ="QUERY TIME ORDER".getBytes();
        ByteBuffer writeBuffer=ByteBuffer.allocate(req.length);
        writeBuffer.put(req);
        writeBuffer.flip();
        sc.write(writeBuffer);
        if(!writeBuffer.hasRemaining())
            System.out.println("Send order 2 server succeed.");
    }
}