Socket编程基础

时间 2019-11-17

原文原文链接

一：socket又称“套接字”，至关于“排插”，一一对应，一个客户端对应一个服务端，原始的socket通讯为，每当一个客户端socket新接入，服务端serverSocket就得就得新建一个线程。缺点：客户端一多就容易搞崩服务端。（为传统的BIO编程）java

例子1:编程

服务端代码：数组

package bhz.bio;

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

// 服务端
public class Server {

    final static int PROT = 8765;
    
    public static void main(String[] args) {
        
        ServerSocket server = null;
        try {
            server = new ServerSocket(PROT);
            System.out.println(" server start .. ");
            //进行阻塞
            Socket socket = server.accept();
            //新建一个线程执行客户端的任务：每来一个Socket就新建一个线程，一多就容易将服务器撑爆。
            new Thread(new ServerHandler(socket)).start();
            
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if(server != null){
                try {
                    server.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            server = null;
        }
                        
    }    
    
}

服务端接收请求后进行run()响应缓存

package bhz.bio;

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

// 服务端接收请求响应后的具体操做
public class ServerHandler implements Runnable{

    private Socket socket ;
    
    public ServerHandler(Socket socket){
        this.socket = socket;
    }
    
    @Override
    public void run() {
        BufferedReader in = null;
        PrintWriter out = null;
        try {
            // 接收客户端数据
            in = new BufferedReader(new InputStreamReader(this.socket.getInputStream()));
            // 向客户端响应数据
            out = new PrintWriter(this.socket.getOutputStream(), true);
            String body = null;
            while(true){
                // 读取客户端数据
                body = in.readLine();
                if(body == null) break;
                System.out.println("Server :" + body);
                out.println("服务器端回送响的应数据.");
            }
            
        } catch (Exception e) {
            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;
        }
        
        
    }

}

客户端请求：服务器

package bhz.bio;

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

public class Client {

    final static String ADDRESS = "127.0.0.1";
    final static int PORT = 8765;
    
    public static void main(String[] args) {
        
        Socket socket = null;
        BufferedReader in = null;
        PrintWriter out = null;
        
        try {
            // 建立Socket链接
            socket = new Socket(ADDRESS, PORT);
            // 接收服务端请求数据
            in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            // 向服务端发送响应数据
            out = new PrintWriter(socket.getOutputStream(), true);
            
            //向服务器端发送数据
            out.println("接收到客户端的请求数据...");
            out.println("接收到客户端的请求数据1111...");
            // 读取服务端响应的数据
            String response = in.readLine();
            System.out.println("Client: " + response);
            
        } catch (Exception e) {
            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;
        }
    }
}

二：为摆脱服务端每接收一次客户端请求就得建立一个线程的问题，能够自定义线程池，限制线程、队列的大小。（为传统的BIO编程）异步

自定义线程池：socket

package bhz.bio2;

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

// 服务端自定的线程池
public class HandlerExecutorPool {

    private ExecutorService executor;
    // 构造方法，定义参数值
    public HandlerExecutorPool(int maxPoolSize, int queueSize){
        this.executor = new ThreadPoolExecutor(
                Runtime.getRuntime().availableProcessors(),
                maxPoolSize, 
                120L, 
                TimeUnit.SECONDS,
                new ArrayBlockingQueue<Runnable>(queueSize));
    }
    
    public void execute(Runnable task){
        this.executor.execute(task);
    }
        
}

服务端使用线程池：ide

package bhz.bio2;

import java.io.BufferedReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

public class Server {

    final static int PORT = 8765;

    public static void main(String[] args) {
        ServerSocket server = null;
        BufferedReader in = null;
        PrintWriter out = null;
        try {
            server = new ServerSocket(PORT);
            System.out.println("server start");
            Socket socket = null;
            // 自定义一个线程池
            HandlerExecutorPool executorPool = new HandlerExecutorPool(50, 1000);
            while(true){
                // 阻塞，接收客户端请求
                socket = server.accept();
                // 将客户端请求放在线程池中，进行服务端响应
                executorPool.execute(new ServerHandler(socket));
            }
            
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if(in != null){
                try {
                    in.close();
                } catch (Exception e1) {
                    e1.printStackTrace();
                }
            }
            if(out != null){
                try {
                    out.close();
                } catch (Exception e2) {
                    e2.printStackTrace();
                }
            }
            if(server != null){
                try {
                    server.close();
                } catch (Exception e3) {
                    e3.printStackTrace();
                }
            }
            server = null;                
        }

    }
        
}

服务端执行请求响应操做：this

package bhz.bio2;

import java.io.BufferedReader;
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;
    }
    
    // 执行线程操做
    @Override
    public void run() {
        BufferedReader in = null;
        PrintWriter out = null;
        try {
            // 接收客户端请求数据
            in = new BufferedReader(new InputStreamReader(this.socket.getInputStream()));
            // 发送服务端响应数据
            out = new PrintWriter(this.socket.getOutputStream(), true);
            String body = null;
            while(true){
                body = in.readLine();
                if(body == null) break;
                System.out.println("Server:" + body);
                out.println("Server response");
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if(in != null){
                try {
                    in.close();
                } catch (Exception e1) {
                    e1.printStackTrace();
                }
            }
            if(out != null){
                try {
                    out.close();
                } catch (Exception e2) {
                    e2.printStackTrace();
                }
            }
            if(socket != null){
                try {
                    socket.close();
                } catch (Exception e3) {
                    e3.printStackTrace();
                }
            }
            socket = null;            
        }
        
        
    }

}

客户端请求：spa

package bhz.bio2;

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

public class Client {
    
    final static String ADDRESS = "127.0.0.1";
    final static int PORT =8765;
    
    public static void main(String[] args) {
        Socket socket = null;
        BufferedReader in = null;
        PrintWriter out = null;
        try {
            // 建立Socket链接
            socket = new Socket(ADDRESS, PORT);
            // 接收服务端返回数据
            in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            // 发送客户端响应数据
            out = new PrintWriter(socket.getOutputStream(), true);
            
            out.println("Client request");
            
            String response = in.readLine();
            System.out.println("Client:" + response);
            
            
        }  catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {
            if(in != null){
                try {
                    in.close();
                } catch (Exception e1) {
                    e1.printStackTrace();
                }
            }
            if(out != null){
                try {
                    out.close();
                } catch (Exception e2) {
                    e2.printStackTrace();
                }
            }
            if(socket != null){
                try {
                    socket.close();
                } catch (Exception e3) {
                    e3.printStackTrace();
                }
            }
            socket = null;                
        }
        
        
        
    }

}

三：NIO的Socket通讯：同步非阻塞

1.NIO三个重要概念：Buffer(缓冲区)、Channel(通道)、选择器（Selector）。

Buffer(缓冲区)：用于通讯传输时的缓冲

Channel(通道)：客户端和服务端都有一个通道，分别为:socketChannel和ServerSocketChannel，这两个类型管道都得注册到选择器(Seletoer)上，由选择器进行统一的通讯管理。

选择器（Selector）：对客户端和服务端的通讯管道进行统一管理

2.Buffer的基本概念操做：

package bhz.nio.test;

import java.nio.IntBuffer;

public class TestBuffer {
    
    public static void main(String[] args) {
        
        // 1 基本操做
        
        //建立指定长度的缓冲区
        IntBuffer buf = IntBuffer.allocate(10);
        buf.put(13);// position位置：0 - > 1   缓冲区加入数据
        buf.put(21);// position位置：1 - > 2
        buf.put(35);// position位置：2 - > 3
        //把位置复位为0，也就是position位置：3 - > 0
        buf.flip();
        System.out.println("使用flip复位：" + buf);
        System.out.println("容量为: " + buf.capacity());    //容量一旦初始化后不容许改变（warp方法包裹数组除外）
        System.out.println("限制为: " + buf.limit());        //因为只装载了三个元素,因此可读取或者操做的元素为3 则limit=3
        
        
        System.out.println("获取下标为1的元素：" + buf.get(1));
        System.out.println("get(index)方法，position位置不改变：" + buf);
        buf.put(1, 4);
        System.out.println("put(index, change)方法，position位置不变：" + buf);;
        
        for (int i = 0; i < buf.limit(); i++) {
            //调用get方法会使其缓冲区位置（position）向后递增一位
            System.out.print(buf.get() + "\t");
        }
        System.out.println("buf对象遍历以后为: " + buf);
        
        
        // 2 wrap方法使用
        /**
        //  wrap方法会包裹一个数组: 通常这种用法不会先初始化缓存对象的长度，由于没有意义，最后还会被wrap所包裹的数组覆盖掉。 
        //  而且wrap方法修改缓冲区对象的时候，数组自己也会跟着发生变化。                     
        int[] arr = new int[]{1,2,5};
        IntBuffer buf1 = IntBuffer.wrap(arr);
        System.out.println(buf1);
        
        IntBuffer buf2 = IntBuffer.wrap(arr, 0 , 2);
        //这样使用表示容量为数组arr的长度，可是可操做的元素只有实际进入缓存区的元素长度
        System.out.println(buf2);
        */
        
        
        // 3 其余方法
        /**
        IntBuffer buf1 = IntBuffer.allocate(10);
        int[] arr = new int[]{1,2,5};
        buf1.put(arr);
        System.out.println(buf1);
        //一种复制方法
        IntBuffer buf3 = buf1.duplicate();
        System.out.println(buf3);
        
        //设置buf1的位置属性
        //buf1.position(0);
        buf1.flip();
        System.out.println(buf1);
        
        System.out.println("可读数据为：" + buf1.remaining());
        
        int[] arr2 = new int[buf1.remaining()];
        //将缓冲区数据放入arr2数组中去
        buf1.get(arr2);
        for(int i : arr2){
            System.out.print(Integer.toString(i) + ",");
        }
        */
        
    }
}

2.使用管道Channel和选择器Seletor的服务端（接收客户端请求）：

package bhz.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.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;

public class Server implements Runnable{
    //1 多路复用器（管理全部的通道）,channel会注册到这个seletor对象上
    private Selector seletor;
    //2 创建缓冲区
    private ByteBuffer readBuf = ByteBuffer.allocate(1024);
    //3 
    private ByteBuffer writeBuf = ByteBuffer.allocate(1024);
    // 构造方法，初始化参数
    public Server(int port){
        try {
            //1 打开路复用器
            this.seletor = Selector.open();
            //2 打开服务器通道
            ServerSocketChannel ssc = ServerSocketChannel.open();
            //3 设置服务器通道为非阻塞模式，为true的话和传统的阻塞socket没区别
            ssc.configureBlocking(false);
            //4 绑定地址
            ssc.bind(new InetSocketAddress(port));
            //5 把服务器通道注册到多路复用器上，而且监听阻塞事件
            ssc.register(this.seletor, SelectionKey.OP_ACCEPT);
            
            System.out.println("Server start, port :" + port);
            
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    
    // 线程开启后执行
    @Override
    public void run() {
        while(true){
            try {
                //1 必需要让多路复用器开始监听
                this.seletor.select();
                //2 返回多路复用器已经选择的结果集，客户端chanal和服务端的serverChanal都会注册到seletor上（注册的值为Key），此处拿到的keys包含了客户端的和服务端的key
                Iterator<SelectionKey> keys = this.seletor.selectedKeys().iterator();
                //3 对结果集进行遍历
                while(keys.hasNext()){
                    //4 获取一个选择的元素
                    SelectionKey key = keys.next();
                    //5 直接从容器中移除就能够了
                    keys.remove();
                    //6 若是是有效的
                    if(key.isValid()){
                        //7 若是为阻塞状态，说明key为服务端的serverSocketChanal。此处NIO为接收客户端请求，同步不阻塞
                        if(key.isAcceptable()){
                            this.accept(key);
                        }
                        //8 若是为可读状态
                        if(key.isReadable()){
                            // 读取每个客户端的SocketChannle发送过来的数据
                            this.read(key);
                        }
                        //9 写数据
                        if(key.isWritable()){
                            //this.write(key); //ssc
                        }
                    }
                    
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    
    private void write(SelectionKey key){
        //ServerSocketChannel ssc =  (ServerSocketChannel) key.channel();
        //ssc.register(this.seletor, SelectionKey.OP_WRITE);
    }
    
    // 接收读取客户端数据
    private void read(SelectionKey key) {
        try {
            //1 清空缓冲区旧的数据
            this.readBuf.clear();
            //2 获取以前注册的socket通道对象
            SocketChannel sc = (SocketChannel) key.channel();
            //3 读取数据
            int count = sc.read(this.readBuf);
            //4 若是没有数据
            if(count == -1){
                key.channel().close();
                key.cancel();
                return;
            }
            //5 有数据则进行读取 读取以前须要进行复位方法(把position 和limit进行复位)
            this.readBuf.flip();
            //6 根据缓冲区的数据长度建立相应大小的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 打印客户端传送过来的结果数据
            String body = new String(bytes).trim();
            System.out.println("Server : " + body);
            
            // 9..能够写回给客户端数据 
            
        } catch (IOException e) {
            e.printStackTrace();
        }
        
    }
    
    // 接收客户端请求
    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,拿到客户端管道，客户端管道也要注册到selector选择器上
            SocketChannel sc = ssc.accept();
            //3 设置阻塞模式：非阻塞
            sc.configureBlocking(false);
            //4 注册到多路复用器上，并设置读取标识
            sc.register(this.seletor, SelectionKey.OP_READ);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    
    public static void main(String[] args) {
        // 开启服务，执行线程run()方法
        new Thread(new Server(8765)).start();;
    }
    
    
}

3.客户端发送请求：

package bhz.nio;

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

public class Client {

    //须要一个Selector 
    public static void main(String[] args) {
        
        //建立链接的地址
        InetSocketAddress address = new InetSocketAddress("127.0.0.1", 8765);
        
        //声明链接通道
        SocketChannel sc = null;
        
        //创建缓冲区
        ByteBuffer buf = ByteBuffer.allocate(1024);
        
        try {
            //打开通道
            sc = SocketChannel.open();
            //进行链接
            sc.connect(address);
            // 链接成功
            while(true){
                //定义一个字节数组，而后使用系统录入功能：
                byte[] bytes = new byte[1024];
                System.in.read(bytes);
                
                //把数据放到缓冲区中
                buf.put(bytes);
                //对缓冲区进行复位
                buf.flip();
                //写出数据
                sc.write(buf);
                //清空缓冲区数据
                buf.clear();
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if(sc != null){
                try {
                    sc.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        
    }
    
}

四：AIO的Socket通讯：AIO是在NIO的基础上，新增了异步通道，在管道前面使用了Asynchronous的，服务端和客户端管道类分别为：AsynchronousServerSocketChannel和AsynchronousSocketChannel。

AIO通讯的服务端为：先建立线程池，线程组使用线程池并负责客户端管道的接入，服务端开启线程组。

1.服务端ServerCompletionHandler类的建立（服务端接收请求后的具体执行内容）：

package bhz.aio;

import java.nio.ByteBuffer;
import java.nio.channels.AsynchronousSocketChannel;
import java.nio.channels.CompletionHandler;
import java.util.concurrent.ExecutionException;

public class ServerCompletionHandler implements CompletionHandler<AsynchronousSocketChannel, Server> {
    
    // 链接成功的操做方法，每个客户端链接进来都进行此操做
    @Override
    public void completed(AsynchronousSocketChannel asc, Server attachment) {
        //当有下一个客户端接入的时候 直接调用Server的accept方法，这样反复执行下去，保证多个客户端均可以阻塞
        attachment.assc.accept(attachment, this);
        read(asc);
    }
    
    // 读取客户端管道数据
    private void read(final AsynchronousSocketChannel asc) {
        //读取数据
        ByteBuffer buf = ByteBuffer.allocate(1024);
        // 异步，不堵塞，执行不成功也直接往下走
        asc.read(buf, buf, new CompletionHandler<Integer, ByteBuffer>() {
            @Override
            public void completed(Integer resultSize, ByteBuffer attachment) {
                //进行读取以后,重置标识位
                attachment.flip();
                //得到读取的字节数
                System.out.println("Server -> " + "收到客户端的数据长度为:" + resultSize);
                //获取读取的数据
                String resultData = new String(attachment.array()).trim();
                System.out.println("Server -> " + "收到客户端的数据信息为:" + resultData);
                // 发送服务端响应数据
                String response = "服务器响应, 收到了客户端发来的数据: " + resultData;
                write(asc, response);
            }
            @Override
            public void failed(Throwable exc, ByteBuffer attachment) {
                exc.printStackTrace();
            }
        });
    }
    
    // 服务端写响应数据
    private void write(AsynchronousSocketChannel asc, String response) {
        try {
            // 设置缓冲区大小
            ByteBuffer buf = ByteBuffer.allocate(1024);
            // 向客户端发送响应数据
            buf.put(response.getBytes());
            buf.flip();
            asc.write(buf).get();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }
    }
    
    // 链接失败的操做方法
    @Override
    public void failed(Throwable exc, Server attachment) {
        exc.printStackTrace();
    }

}

2.服务端：

package bhz.aio;

import java.net.InetSocketAddress;
import java.nio.channels.AsynchronousChannelGroup;
import java.nio.channels.AsynchronousServerSocketChannel;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class Server {
    //线程池
    private ExecutorService executorService;
    //线程组
    private AsynchronousChannelGroup threadGroup;
    //服务器通道
    public AsynchronousServerSocketChannel assc;
    
    public Server(int port){
        try {
            //建立一个缓存池
            executorService = Executors.newCachedThreadPool();
            //建立线程组：异步，负责接收client的接入
            threadGroup = AsynchronousChannelGroup.withCachedThreadPool(executorService, 1);
            //建立服务器通道
            assc = AsynchronousServerSocketChannel.open(threadGroup);
            //进行绑定接收端口
            assc.bind(new InetSocketAddress(port));
            
            System.out.println("server start , port : " + port);
            //进行阻塞：一直等客户端的请求，this指当前对象。new ServerCompletionHandler()为进行通讯的具体操做内容
            assc.accept(this, new ServerCompletionHandler());
            //一直阻塞 不让服务器中止
            Thread.sleep(Integer.MAX_VALUE);
            
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    public static void main(String[] args) {
        Server server = new Server(8765);
    }
    
}

3.客户端：

package bhz.aio;

import java.io.UnsupportedEncodingException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.AsynchronousSocketChannel;
import java.util.concurrent.ExecutionException;

public class Client implements Runnable{

    private AsynchronousSocketChannel asc ;
    
    public Client() throws Exception {
        asc = AsynchronousSocketChannel.open();
    }
    
    // 链接服务端地址
    public void connect(){
        asc.connect(new InetSocketAddress("127.0.0.1", 8765));
    }
    
    // 向服务端写数据
    public void write(String request){
        try {
            asc.write(ByteBuffer.wrap(request.getBytes())).get();
            read();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    //接收服务端数据
    private void read() {
        ByteBuffer buf = ByteBuffer.allocate(1024);
        try {
            asc.read(buf).get();
            buf.flip();
            byte[] respByte = new byte[buf.remaining()];
            buf.get(respByte);
            System.out.println(new String(respByte,"utf-8").trim());
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
    }
    
    @Override
    public void run() {
        while(true){
            
        }
    }
    
    public static void main(String[] args) throws Exception {
        Client c1 = new Client();
        c1.connect();
        
        Client c2 = new Client();
        c2.connect();
        
        Client c3 = new Client();
        c3.connect();
        
        new Thread(c1, "c1").start();
        new Thread(c2, "c2").start();
        new Thread(c3, "c3").start();
        
        Thread.sleep(1000);
        
        c1.write("c1 aaa");
        c2.write("c2 bbbb");
        c3.write("c3 ccccc");
    }
    
}

客户端发送请求，接收服务端的数据：

服务器响应, 收到了客户端发来的数据: c1 aaa
服务器响应, 收到了客户端发来的数据: c2 bbbb
服务器响应, 收到了客户端发来的数据: c3 ccccc

五：思考：BIO和NIO，NIO和AIO的区别？（这三者如今开发都不会用了）