JAVA-TCP

 

 TCP的机制：

 

 TCP链接、传输过程。

TCP能做什么：

1、聊天消息传输.

2、单人语音、视频等

限制：无法进行广播、多播操作.

核心API：

 

 

 

 

 

客户端：

 

 服务端：

 

 四次挥手：

 传输可靠性：

排序、顺序发送、顺序组装

丢弃、超时

重发机制、定时器

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.*;
import java.nio.ByteBuffer;

public class TcpClient {
    private static final int PORT = 20000;
    private static final int LOCAL_PORT = 20001;

    public static void main(String[] args) throws IOException {
        Socket socket = createSocket();

        initSocket(socket);

        // 链接到本地20000端口，超时时间3秒，超过则抛出超时异常
        socket.connect(new InetSocketAddress(Inet4Address.getLocalHost(), PORT), 3000);

        System.out.println("已发起服务器连接，并进入后续流程～");
        System.out.println("客户端信息：" + socket.getLocalAddress() + " P:" + socket.getLocalPort());
        System.out.println("服务器信息：" + socket.getInetAddress() + " P:" + socket.getPort());

        try {
            // 发送接收数据
            todo(socket);
        } catch (Exception e) {
            System.out.println("异常关闭");
        }

        // 释放资源
        socket.close();
        System.out.println("客户端已退出～");

    }

    private static Socket createSocket() throws IOException {
        /*
        // 无代理模式，等效于空构造函数
        Socket socket = new Socket(Proxy.NO_PROXY);

        // 新建一份具有HTTP代理的套接字，传输数据将通过www.baidu.com:8080端口转发
        Proxy proxy = new Proxy(Proxy.Type.HTTP,
                new InetSocketAddress(Inet4Address.getByName("www.baidu.com"), 8800));
        socket = new Socket(proxy);

        // 新建一个套接字，并且直接链接到本地20000的服务器上
        socket = new Socket("localhost", PORT);

        // 新建一个套接字，并且直接链接到本地20000的服务器上
        socket = new Socket(Inet4Address.getLocalHost(), PORT);

        // 新建一个套接字，并且直接链接到本地20000的服务器上，并且绑定到本地20001端口上
        socket = new Socket("localhost", PORT, Inet4Address.getLocalHost(), LOCAL_PORT);
        socket = new Socket(Inet4Address.getLocalHost(), PORT, Inet4Address.getLocalHost(), LOCAL_PORT);
        */

        Socket socket = new Socket();
        // 绑定到本地20001端口
        socket.bind(new InetSocketAddress(Inet4Address.getLocalHost(), LOCAL_PORT));

        return socket;
    }

    private static void initSocket(Socket socket) throws SocketException {
        // 设置读取超时时间为2秒
        socket.setSoTimeout(2000);

        // 是否复用未完全关闭的Socket地址，对于指定bind操作后的套接字有效
        socket.setReuseAddress(true);

        // 是否开启Nagle算法
        socket.setTcpNoDelay(true);

        // 是否需要在长时无数据响应时发送确认数据（类似心跳包），时间大约为2小时
        socket.setKeepAlive(true);

        // 对于close关闭操作行为进行怎样的处理；默认为false，0
        // false、0：默认情况，关闭时立即返回，底层系统接管输出流，将缓冲区内的数据发送完成
        // true、0：关闭时立即返回，缓冲区数据抛弃，直接发送RST结束命令到对方，并无需经过2MSL等待
        // true、200：关闭时最长阻塞200毫秒，随后按第二情况处理
        socket.setSoLinger(true, 20);

        // 是否让紧急数据内敛，默认false；紧急数据通过 socket.sendUrgentData(1);发送
        socket.setOOBInline(true);

        // 设置接收发送缓冲器大小
        socket.setReceiveBufferSize(64 * 1024 * 1024);
        socket.setSendBufferSize(64 * 1024 * 1024);

        // 设置性能参数：短链接，延迟，带宽的相对重要性
        socket.setPerformancePreferences(1, 1, 0);
    }

    private static void todo(Socket client) throws IOException {
        // 得到Socket输出流
        OutputStream outputStream = client.getOutputStream();


        // 得到Socket输入流
        InputStream inputStream = client.getInputStream();
        byte[] buffer = new byte[256];
        ByteBuffer byteBuffer = ByteBuffer.wrap(buffer);

        // byte
        byteBuffer.put((byte) 126);

        // char
        char c = 'a';
        byteBuffer.putChar(c);

        // int
        int i = 2323123;
        byteBuffer.putInt(i);

        // bool
        boolean b = true;
        byteBuffer.put(b ? (byte) 1 : (byte) 0);

        // Long
        long l = 298789739;
        byteBuffer.putLong(l);


        // float
        float f = 12.345f;
        byteBuffer.putFloat(f);


        // double
        double d = 13.31241248782973;
        byteBuffer.putDouble(d);

        // String
        String str = "Hello你好！";
        byteBuffer.put(str.getBytes());

        // 发送到服务器
        outputStream.write(buffer, 0, byteBuffer.position() + 1);

        // 接收服务器返回
        int read = inputStream.read(buffer);
        System.out.println("收到数量：" + read);

        // 资源释放
        outputStream.close();
        inputStream.close();
    }
}

　　

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Inet4Address;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.nio.ByteBuffer;


public class TcpServer {
    private static final int PORT = 20000;

    public static void main(String[] args) throws IOException {
        ServerSocket server = createServerSocket();

        initServerSocket(server);

        // 绑定到本地端口上
        server.bind(new InetSocketAddress(Inet4Address.getLocalHost(), PORT), 50);


        System.out.println("服务器准备就绪～");
        System.out.println("服务器信息：" + server.getInetAddress() + " P:" + server.getLocalPort());


        // 等待客户端连接
        for (; ; ) {
            // 得到客户端
            Socket client = server.accept();
            // 客户端构建异步线程
            ClientHandler clientHandler = new ClientHandler(client);
            // 启动线程
            clientHandler.start();
        }

    }

    private static ServerSocket createServerSocket() throws IOException {
        // 创建基础的ServerSocket
        ServerSocket serverSocket = new ServerSocket();

        // 绑定到本地端口20000上，并且设置当前可允许等待链接的队列为50个
        //serverSocket = new ServerSocket(PORT);

        // 等效于上面的方案，队列设置为50个
        //serverSocket = new ServerSocket(PORT, 50);

        // 与上面等同
        // serverSocket = new ServerSocket(PORT, 50, Inet4Address.getLocalHost());

        return serverSocket;
    }

    private static void initServerSocket(ServerSocket serverSocket) throws IOException {
        // 是否复用未完全关闭的地址端口
        serverSocket.setReuseAddress(true);

        // 等效Socket#setReceiveBufferSize
        serverSocket.setReceiveBufferSize(64 * 1024 * 1024);

        // 设置serverSocket#accept超时时间
        // serverSocket.setSoTimeout(2000);

        // 设置性能参数：短链接，延迟，带宽的相对重要性
        serverSocket.setPerformancePreferences(1, 1, 1);
    }

    /**
     * 客户端消息处理
     */
    private static class ClientHandler extends Thread {
        private Socket socket;

        ClientHandler(Socket socket) {
            this.socket = socket;
        }

        @Override
        public void run() {
            super.run();
            System.out.println("新客户端连接：" + socket.getInetAddress() +
                    " P:" + socket.getPort());

            try {
                // 得到套接字流
                OutputStream outputStream = socket.getOutputStream();
                InputStream inputStream = socket.getInputStream();

                byte[] buffer = new byte[256];
                int readCount = inputStream.read(buffer);
                ByteBuffer byteBuffer = ByteBuffer.wrap(buffer, 0, readCount);

                // byte
                byte be = byteBuffer.get();

                // char
                char c = byteBuffer.getChar();

                // int
                int i = byteBuffer.getInt();

                // bool
                boolean b = byteBuffer.get() == 1;

                // Long
                long l = byteBuffer.getLong();

                // float
                float f = byteBuffer.getFloat();

                // double
                double d = byteBuffer.getDouble();

                // String
                int pos = byteBuffer.position();
                String str = new String(buffer, pos, readCount - pos - 1);

                System.out.println("收到数量：" + readCount + " 数据："
                        + be + "
"
                        + c + "
"
                        + i + "
"
                        + b + "
"
                        + l + "
"
                        + f + "
"
                        + d + "
"
                        + str + "
");

                outputStream.write(buffer, 0, readCount);
                outputStream.close();
                inputStream.close();

            } catch (Exception e) {
                System.out.println("连接异常断开");
            } finally {
                // 连接关闭
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

            System.out.println("客户端已退出：" + socket.getInetAddress() +
                    " P:" + socket.getPort());

        }
    }
}