java IO(BIO)、NIO、AIO

IO

服务端ServerSocket 客户端Socket

缺点每次客户端建立连接都会另外启一个线程处理。读取和发送数据都是阻塞式的。

如果1000个客户端建立连接将会产生1000个线程

Server端

package bhz.bio.test;

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

public class Server {
    private int port;
    private ServerSocket serverSocket;

    public Server(int port) {
        this.port = port;

    }

    public void start() throws IOException {
        try {
            serverSocket = new ServerSocket(port);
            while (true) {
               Socket socket = serverSocket.accept();// 阻塞等待客户端建立连接
               new Thread(new ServerHandler(socket)).start();//另外起一個線程處理客戶端的請求
            }
        } catch (IOException e) {
             e.printStackTrace();
            // TODO Auto-generated catch block
            System.out.println("服务器启动失败");
        }finally {
            if(serverSocket!=null) {
                serverSocket.close();//释放资源操作
            }

        }

    }
}

ServerHandler

package bhz.bio.test;

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

public class ServerHandler implements Runnable {
    private Socket socket;

    public ServerHandler(Socket socket) {
        this.socket = socket;
    }

    @Override
    public void run() {
        // TODO Auto-generated method stub

        BufferedReader in = null;
        PrintWriter out = null;
        try {
            while (true) {
                // 监听客户端的发送消息
                out = new PrintWriter(socket.getOutputStream(),true);
                in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                String content = in.readLine();

                System.out.println("接收到客户端发送的消息:" + content);//
                out.println("哈哈哈");
            }
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {
            if(in != null){
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(out != null){
                try {
                    out.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
            if(socket != null){
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            socket = null;
        }

    }

}

客户端

package bhz.bio.test;

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

public class Client {
    private String ip;
    private int port;
    private Socket socket;
    private PrintWriter out;
    private BufferedReader in;
    public Client(String ip, int port) {
        this.ip = ip;
        this.port = port;
    }

    public void connect() {
        try {
            socket = new Socket(ip, port);
            out = new PrintWriter(socket.getOutputStream(),true);
            in=new BufferedReader(new InputStreamReader(socket.getInputStream()));
        } catch (Exception e) {
            // TODO: handle exception
            System.out.println("建立連接失敗");
        }

    }

    public void send(String message) throws IOException {

         out.println(message);

         try {
             String content=in.readLine();
               System.out.println("接收到服务端的数据:"+content);
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }

    }
}

测试类

package bhz.bio.test;

import java.io.IOException;

public class mainTest {
  public static void main(String[] args) {
      //启动服务端
    new Thread(new Runnable() {

        @Override
        public void run() {
            // TODO Auto-generated method stub
            Server server=new Server(8089);
            try {
                server.start();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            try {
                Thread.sleep(Integer.MAX_VALUE);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }
    }).start();

    new Thread(new Runnable() {

        @Override
        public void run() {
            // TODO Auto-generated method stub
            Client client=new Client("127.0.0.1", 8089);
            client.connect();//与服务器建立连接
            try {
                client.send("你好呀");
                client.send("你好呀2");
            } catch (IOException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }
            try {
                Thread.sleep(Integer.MAX_VALUE);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }).start();
}
}

输出

接收到客户端发送的消息:你好呀
接收到服务端的数据:哈哈哈
接收到客户端发送的消息:你好呀2
接收到服务端的数据:哈哈哈

使用线程池限制客户端数量(伪异步)

public class Server {
    private int port;
    private ServerSocket serverSocket;

    private ExecutorService executorService;
    public Server(int port) {
        this.port = port;
        executorService=Executors.newFixedThreadPool(50);//限制同时在线客户端数量为10个

    }

    public void start() throws IOException {
        try {
            serverSocket = new ServerSocket(port);
            while (true) {
               Socket socket = serverSocket.accept();// 阻塞等待客户端建立连接
               executorService.execute(new ServerHandler(socket));//线程池处理
            }
        } catch (IOException e) {
             e.printStackTrace();
            // TODO Auto-generated catch block
            System.out.println("服务器启动失败");
        }finally {
            if(serverSocket!=null) {
                serverSocket.close();//释放资源操作
            }
        }

    }
}

Nio

nio改善了io一个客户端建立连接就创建一个线程监听请求的模型。

nio的核心概念

1.Channel(   负责读写数据 可以channel读取数据到buffer也可以通过channel写入数据到channel)

• FileChannel
• DatagramChannel  能通过UDP读写网络中的数据
• SocketChannel 能通过TCP读写网络中的数据。
• ServerSocketChannel 可以监听新进来的TCP连接，像Web服务器那样。对每一个新进来的连接都会创建一个SocketChannel。

2.Buffers

• ByteBuffer
• CharBuffer
• DoubleBuffer
• FloatBuffer
• IntBuffer
• LongBuffer
• ShortBuffer

存储数据的容器

3.Selectors

负责轮询Channel的状态进行对应的操作。发送消息和建立连接都需要往selectors注册channel (一个selectors可以监听无数个channel状态)

buffer的使用

建立一个指定大小的缓冲区

private ByteBuffer readBuf = ByteBuffer.allocate(1024);

往buffer容器添加数据内容position字段都会累加。

读取数据是根据position字段来读取

所以读取之前要记得重置position位置为0

readBuf.flip();

读取缓冲区里面数据

//根据缓冲区的数据长度创建相应大小的byte数组，接收缓冲区的数据
            byte[] bytes = new byte[this.readBuf.remaining()];
            / 接收缓冲区数据
            this.readBuf.get(bytes);
            //打印结果
            String body = new String(bytes).trim();

服務端

package bhz.nio.test;

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;

public class Server {

    private int port;
    private ServerSocketChannel serverSocketChannel;
    private Selector selector;
    //2 建立缓冲区
    private ByteBuffer readBuf = ByteBuffer.allocate(1024);
    private ByteBuffer writeBuf = ByteBuffer.allocate(1024);
    public Server(int port) {
        this.port = port;
    }
    public void start() throws IOException {
        selector=Selector.open();//创建选择器
        serverSocketChannel=ServerSocketChannel.open();//创建监听通道
        serverSocketChannel.configureBlocking(false);//开启非阻塞模式
        serverSocketChannel.socket().bind(new InetSocketAddress(port));//绑定端口
        //把服务器通道注册到多路复用器上，并且监听阻塞事件
        serverSocketChannel.register(this.selector, SelectionKey.OP_ACCEPT);
        //轮询多路复用器
        new Thread(new Runnable() {

            @Override
            public void run() {
                // TODO Auto-generated method stub
                while (true) {
                      //阻塞,只有当至少一个注册的事件发生的时候才会继续.
                    try {
                        selector.select();
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                    // 返回多路复用器已经选择的结果集
                    Iterator<SelectionKey> selectionKeys=selector.selectedKeys().iterator();
                    //3 进行遍历
                    while(selectionKeys.hasNext()){
                        //4 获取一个选择的元素
                        SelectionKey key = selectionKeys.next();
                        //5 直接从容器中移除就可以了
                        selectionKeys.remove();
                        //6 如果是有效的
                        if(key.isValid()){
                            //7 如果为阻塞状态
                            if(key.isAcceptable()){
                                accept(key);
                            }
                            //8 如果为可读状态
                            if(key.isReadable()){
                                read(key);
                            }
                            //9 写数据
                            if(key.isWritable()){
                                //this.write(key); //ssc
                            }
                        }

                    }

                }

            }

        }).start();
    }

    private void accept(SelectionKey key) {
        try {
            //1 获取服务通道
            ServerSocketChannel ssc =  (ServerSocketChannel) key.channel();
            //2 执行阻塞方法
            SocketChannel sc = ssc.accept();
            //3 设置阻塞模式
            sc.configureBlocking(false);
            //4 注册到多路复用器上，并设置读取标识
            sc.register(this.selector, SelectionKey.OP_READ);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    private void read(SelectionKey key) {
        try {
            //1 清空缓冲区旧的数据
            this.readBuf.clear();
            //2 获取之前注册的socket通道对象
            SocketChannel sc = (SocketChannel) key.channel();
            //3 读取数据
            int count = sc.read(this.readBuf);
            //4 如果没有数据
            if(count == -1){
                key.channel().close();
                key.cancel();
                return;
            }
            //5 有数据则进行读取 读取之前需要进行复位方法(把position 和limit进行复位)
            this.readBuf.flip();
            //6 根据缓冲区的数据长度创建相应大小的byte数组，接收缓冲区的数据
            byte[] bytes = new byte[this.readBuf.remaining()];
            //7 接收缓冲区数据
            this.readBuf.get(bytes);
            //8 打印结果
            String body = new String(bytes).trim();
            System.out.println("Server : " + body);

            // 9..可以写回给客户端数据 

        } catch (IOException e) {
            e.printStackTrace();
        }

    }

}

客戶端

package bhz.nio.test;

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;

public class Client {

    private SocketChannel socketChannel;
    private ByteBuffer readBuf = ByteBuffer.allocate(1024);
    private ByteBuffer writeBuf = ByteBuffer.allocate(1024);
    private Selector selector;
    public void connect(String ip,int port) throws IOException {
        selector=Selector.open();//创建选择器

        socketChannel=SocketChannel.open();//创建连接

         if(socketChannel.connect(new InetSocketAddress(ip,port)));
         else socketChannel.register(selector, SelectionKey.OP_CONNECT);
         socketChannel.configureBlocking(false);
        socketChannel.register(selector, SelectionKey.OP_CONNECT); //注册到多路复用器
        new Thread(new Runnable() {

            @Override
            public void run() {
                // TODO Auto-generated method stub
                   SelectionKey key = null;
                while (true) {
                    try {
                        selector.select();
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                    Iterator<SelectionKey> selectionKeys=selector.selectedKeys().iterator();

                    while (selectionKeys.hasNext()) {
                        key=selectionKeys.next();
                        if(key.isReadable()) {

                        }

                    }

                }

            }
        }).start();
    }
    private void read(SelectionKey key) {
        try {
            //1 清空缓冲区旧的数据
            this.readBuf.clear();
            //2 获取之前注册的socket通道对象
            SocketChannel sc = (SocketChannel) key.channel();
            //3 读取数据
            int count = sc.read(this.readBuf);
            //4 如果没有数据
            if(count == -1){
                key.channel().close();
                key.cancel();
                return;
            }
            //5 有数据则进行读取 读取之前需要进行复位方法(把position 和limit进行复位)
            this.readBuf.flip();
            //6 根据缓冲区的数据长度创建相应大小的byte数组，接收缓冲区的数据
            byte[] bytes = new byte[this.readBuf.remaining()];
            //7 接收缓冲区数据
            this.readBuf.get(bytes);
            //8 打印结果
            String body = new String(bytes).trim();
            System.out.println("client : " + body);

            // 9..可以写回给客户端数据 

        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    public void write(String message) throws IOException {
        byte[] bytes =message.getBytes();

        //把数据放到缓冲区中
        writeBuf.put(bytes);
        //对缓冲区进行复位
        writeBuf.flip();
        //写出数据
        socketChannel.write(writeBuf);
        //清空缓冲区数据
        writeBuf.clear();
    }
}

測試類

package bhz.nio.test;

import java.io.IOException;

public class TestMain {
    public static void main(String[] args) throws InterruptedException {
        final Server server = new Server(8088);
        final Client client=new Client();

        new Thread(new Runnable() {

            @Override
            public void run() {
                // TODO Auto-generated method stub
                try {
                    server.start();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                try {
                    Thread.sleep(Integer.MAX_VALUE);
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }

        }).start();
        Thread.sleep(2000);
        new Thread(new Runnable() {

            @Override
            public void run() {
                // TODO Auto-generated method stub
                try {
                    client.connect("127.0.0.1", 8088);
                    client.write("哈哈哈哈");
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

            }
        }).start();
    }
}

AIO

服務端類AsynchronousServerSocketChannel

客戶端類AsynchronousSocketChannel

服务端

public class Server {

    private int port;
    //服务器通道
     AsynchronousServerSocketChannel serverSocketChannel;
    //线程组
    private AsynchronousChannelGroup threadGroup;
    private ExecutorService executorService;
    public Server(int port) {
        this.port=port;

    }
    public void start() throws IOException {
        //创建线程池
        executorService=Executors.newCachedThreadPool();
        //创建线程组
        threadGroup = AsynchronousChannelGroup
                    .withThreadPool(executorService);
        //创建服务器通道
        serverSocketChannel = AsynchronousServerSocketChannel.open(threadGroup);
        //进行绑定
        serverSocketChannel.bind(new InetSocketAddress(port));

        serverSocketChannel.accept(this, new ServerHandler());
    }
}

异步读handle

/**
 * 客户端接收服务器数据回调
 * @author Administrator
 *
 */
public class ClientReadHandler implements CompletionHandler<Integer, ByteBuffer> {

    @Override
    public void completed(Integer result, ByteBuffer attachment) {
        // TODO Auto-generated method stub
        attachment.flip();//读模式 position设置为0
        byte[] datas=new byte[attachment.remaining()];
        attachment.get(datas);
        try {
            System.out.println("服务端响应"+new String(datas,"utf-8"));
        } catch (UnsupportedEncodingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

    @Override
    public void failed(Throwable exc, ByteBuffer attachment) {
        // TODO Auto-generated method stub
        System.out.println("客户端读取失败");

    }

}

客户端

package bnz.aio.test;

import java.io.IOException;
import java.io.Writer;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.AsynchronousSocketChannel;
import java.nio.channels.CompletionHandler;

public class Client implements CompletionHandler<Void, Client> {
    private String ip;
    private int port;
    private AsynchronousSocketChannel asc;

    public Client(String ip, int port) {
        this.ip = ip;
        this.port = port;
    }

    public void connect() throws IOException {
        asc = AsynchronousSocketChannel.open();
        asc.connect(new InetSocketAddress(ip, port), this, this);
          //读取数据
        ByteBuffer readBuffer = ByteBuffer.allocate(1024);
         asc.read(readBuffer,readBuffer,new ClientReadHandler());//服务器写入数据回调
    }

    public void Writer(String message) {
        byte[] req = message.getBytes();
        ByteBuffer writeBuffer = ByteBuffer.allocate(req.length);
        writeBuffer.put(req);
        writeBuffer.flip();
        //异步写
        asc.write(writeBuffer,writeBuffer, new WriteHandler(asc));
    }
    //连接成功的回调

    @Override
    public void completed(Void result, Client attachment) {
        // TODO Auto-generated method stub
        System.out.println("建立连接成功");

    }

    //异常回调
    @Override
    public void failed(Throwable exc, Client attachment) {
        // TODO Auto-generated method stub
        System.out.println("建立连接失败");

    }
}

读handle

/**
 * 客户端接收服务器数据回调
 * @author Administrator
 *
 */
public class ClientReadHandler implements CompletionHandler<Integer, ByteBuffer> {

    @Override
    public void completed(Integer result, ByteBuffer attachment) {
        // TODO Auto-generated method stub
        attachment.flip();//读模式 position设置为0
        byte[] datas=new byte[attachment.remaining()];
        attachment.get(datas);
        try {
            System.out.println("服务端响应"+new String(datas,"utf-8"));
        } catch (UnsupportedEncodingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

    @Override
    public void failed(Throwable exc, ByteBuffer attachment) {
        // TODO Auto-generated method stub
        System.out.println("客户端读取失败");

    }

}

写handle

/**
 * 客户端异步写回调
 * @author Administrator
 *
 */
public class WriteHandler implements CompletionHandler<Integer, ByteBuffer> {

    private AsynchronousSocketChannel channel;
     public WriteHandler(AsynchronousSocketChannel asynchronousSocketChannel) {
        // TODO Auto-generated constructor stub
         this.channel=asynchronousSocketChannel;
    }
    @Override
    public void completed(Integer result, ByteBuffer attachment) {
        // TODO Auto-generated method stub
        attachment.hasRemaining();
        channel.write(attachment,attachment,this);
    }

    @Override
    public void failed(Throwable exc, ByteBuffer attachment) {
        // TODO Auto-generated method stub
        System.out.println("数据写入失败");
    }

}

io nio  aio比较

io 同步阻塞 jdk4以前的网络通信模型，io一个连接需要开启一个线程处理 ，在大量连接情况下服务器会创建N个线程。导致cpu线程调度频繁 性能底下 (同步阻塞)

nio 同步非阻塞  jdk4之后的网络通信,主要是为了解决io模型下一个线程处理一个连接的性能问题， 引入事件驱动。l客户端连接服务端注册到复用器，然后轮询复用器注册连接的状态。只需要一个线程处理   (同步非阻塞)

aio 异步非阻塞 jdk7推出的网络通信框架 跟nio不同的是 读写都是异步的(完全交给内核处理)  完成后通知应用程序

同步阻塞 可以理解为买票排队。没买到票之前什么也不能做。

同步非阻塞 可以理解为邮局。 经常需要跑去邮局去询问有没有自己的邮件。

异步非阻塞 可以理解为去饭店点餐 然后回家 饭店做好打包后 送上门

应用场景

io可以应用在少量且固定连接的网络通信  应为io的模型更简单容易理解

nio 在大量连接情况使用

aio在大量连接 且读写数据非常大的情况下