Java network programming - summary overview

IP Address

IP Address IntAddress

• Only locate a computer on the network
• 127.0.0.1： Local localhost
• IP Classification of addresses
  • ipV4/ipV6
    • ipV4:127.0.0.1,4 Byte composition ;0~255,42 Billion ~;30 Billion in North America , Asia 4 Billion ;2011 It ran out in
    • ipV6:128 position .8 Signed integers
  • Public network （ Internet ）- The private network （ LAN ）
    • ABCD Class address
    • 192.168 .xx.xx, Specifically for use within an organization
• domain name ： Aspect memory , No records IP The problem of

// test IP
public class TestInetAddress {
    public static void main(String[] args) {
        try {
            // Look up the local address 
            InetAddress inetAddress = InetAddress.getByName("127.0.0.1");
            System.out.println(inetAddress);
            InetAddress localhost = InetAddress.getByName("localhost");
            System.out.println(localhost);
            InetAddress localHost = InetAddress.getLocalHost();
            System.out.println(localHost);

            // Check the website ip Address 
            InetAddress inetAddress1 = InetAddress.getByName("www.baidu.com");
            System.out.println(inetAddress1);

            // Common methods 
            System.out.println(inetAddress1.getHostAddress());//ip
            System.out.println(inetAddress1.getHostName());// domain name , Or your own name 
        } catch (UnknownHostException e) {
            e.printStackTrace();
        }
    }
}

port

ip Equivalent to province / City / District / Street, / floor , The port is the house number ; A port represents the process of a program on a computer

• Different processes have different port numbers ！ It's used to distinguish software ！
• Be regulated 0~65535
• TCP,UDP：65535*2;tcp：80;udp：80
• Port classification
  • Public port 0~1023
    • HTTP:80
    • HTTPS:443
    • FTP:21
    • Telent:23
  • Program registration port ：1024~49151, Assign users or programs
    • Tomcat：8080
    • MySQL：3306
    • Orcal：1521
  • dynamic 、 private ：49152~65535

//CMD
netstat -ano # Look at all the ports 
netstat -ano|findstr "5900" # View the specified port 
tasklist|findstr "8696" # View the process of the specified port 

// port 
public class TestInetSocketAddress {
    public static void main(String[] args) {
        InetSocketAddress socketAddress = new InetSocketAddress("127.0.0.1", 8080);
        System.out.println(socketAddress);

        System.out.println(socketAddress.getAddress());
        System.out.println(socketAddress.getHostName());// Address 
        System.out.println(socketAddress.getPort());// port 
    }
}

Communication protocol

agreement ： Appointment , Joint compliance , Can understand

Network communication protocol ： rate , Transmission rate , The code structure , Transmission control ....

TCP/IP Protocol cluster ： It's actually a set of agreements

important

• TCP： User transport protocol
• UDP： User datagram protocol

TCP UDP contrast

TCP： Make a phone call

• Connect , Stable
• Three handshakes , Four waves
• client 、 Server side
• Transmission complete , Release the connection , Low efficiency

UDP： texting

• Not connected , unstable
• client 、 Server side ： There are no clear boundaries
• Ready or not , Can be sent to you

TCP Realize chat

// Server side 
public class TcpServerDemo01 {
    public static void main(String[] args) {
        ServerSocket serverSocket = null;
        Socket accept=null;
        InputStream is=null;
        ByteArrayOutputStream baos=null;
        try {
            //1. You have to have an address 
            serverSocket = new ServerSocket(9999);

            while (true){
                //2. Wait for the client to connect 
                accept = serverSocket.accept();
                //3. Read the message from the client 
                is = accept.getInputStream();

                // Pipe flow 
                baos = new ByteArrayOutputStream();
                byte[] bytes = new byte[1024];
                int len;
                while ((len=is.read(bytes))!=-1){
                    baos.write(bytes,0,len);
                }
                System.out.println(baos.toString());
            }

        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            // Closed flow 
            try {
                baos.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                is.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                accept.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                serverSocket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
    }
}

// client 
public class TcpClientDemo01 {
    public static void main(String[] args) {
        Socket socket=null;
        OutputStream os=null;

        try {
            //1. Until the server's address 
            InetAddress serverIP= InetAddress.getByName("127.0.0.1");
            int port=9999;
            //2. Create a socker Connect 
            try {
                socket = new Socket(serverIP,port);
                //3. Send a message  IO flow 
                os = socket.getOutputStream();
                os.write("Hello".getBytes());
            } catch (IOException e) {
                e.printStackTrace();
            }


        } catch (UnknownHostException e) {
            e.printStackTrace();
        }finally {
            try {
                os.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                socket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

TCP Upload files

// Server side 
public class TcpServerDemo02 {
    public static void main(String[] args) throws Exception{
        //1. Create services 
        ServerSocket serverSocket = new ServerSocket(9000);
        //2. Listen for client connections 
        Socket accept = serverSocket.accept();// Blocking monitoring , Will be waiting for the client to connect 
        //3. Get input stream 
        InputStream is = accept.getInputStream();

        //4. File output 
        FileOutputStream fos = new FileOutputStream("receive.jpg");
        byte[] by = new byte[1024];
        int len;
        while ((len=is.read(by))!=-1){
            fos.write(by,0,len);
        }

        // Inform the client that I have finished receiving 
        OutputStream os = accept.getOutputStream();
        os.write(" End of reception ".getBytes());

        os.close();
        fos.close();
        is.close();
        accept.close();
        serverSocket.close();
    }
}

// client 
public class TcpClientDemo02 {
    public static void main(String[] args) throws Exception{
        //1. Create a socket Connect 
        Socket socket = new Socket(InetAddress.getByName("127.0.0.1"),9000);
        //2. Create an output stream 
        OutputStream os = socket.getOutputStream();

        //3. Read the file 
        FileInputStream fis = new FileInputStream("D:\\WorkSpace\\JavaSE\\ Basic grammar \\111.png");
        //4. Write a document 
        byte[] by = new byte[1024];
        int len;
        while ((len=fis.read(by))!=-1){
            os.write(by,0,len);
        }

        // Notification server , I've finished the transmission 
        socket.shutdownOutput();

        // Confirm that the server has received , To disconnect 
        InputStream is = socket.getInputStream();
        ByteArrayOutputStream baos = new ByteArrayOutputStream();

        byte[] bytes = new byte[1024];
        int leng;
        while ((leng=is.read(bytes))!=-1){
            baos.write(bytes,0,leng);
        }
        System.out.println(baos.toString());

        baos.close();
        is.close();
        os.close();
        fis.close();
        socket.close();
    }
}

UDP message sending

// The sender 
public class UdpClientDemo01 {
    public static void main(String[] args) throws Exception{
        //1. Build a Socket
        DatagramSocket datagramSocket = new DatagramSocket();

        //2. Build a package 
        String msg=" How do you do , The server ！";
        InetAddress localhost = InetAddress.getByName("localhost");
        int port = 9090;

        // data 、 The length of the data starts with 、 To whom 
        DatagramPacket datagramPacket = new DatagramPacket(msg.getBytes(),0,msg.getBytes().length,localhost,port);

        // Send package 
        datagramSocket.send(datagramPacket);

        //4. Closed flow 
        datagramSocket.close();
    }
}

// The receiving party 
public class UdpServerDemo01 {
    public static void main(String[] args) throws Exception{
        // Open ports 
        DatagramSocket datagramSocket = new DatagramSocket(9090);
        // receive data 
        byte[] bytes = new byte[1024];
        DatagramPacket datagramPacket = new DatagramPacket(bytes,0,bytes.length);

        datagramSocket.receive(datagramPacket);// Blocking reception 

        System.out.println(datagramPacket.getAddress());
        System.out.println(new String(datagramPacket.getData(),0,datagramPacket.getLength()));
    }
}

UDP Chat to achieve

// The sender 
public class UdpSenderDemo01 {
    public static void main(String[] args) throws Exception{

        DatagramSocket datagramSocket = new DatagramSocket(8888);

        // Prepare the data ： The console reads System.in
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

        while (true){
            String data=reader.readLine();
            byte[] bytes = data.getBytes();
            DatagramPacket datagramPacket = new DatagramPacket(bytes,0,bytes.length,new InetSocketAddress("localhost",6666));
            datagramSocket.send(datagramPacket);
            if(bytes.equals("byebye")){
                break;
            }
        }
        datagramSocket.close();
    }
}

// The receiving party 
public class UdpReceiveDemo01 {
    public static void main(String[] args) throws Exception{
        DatagramSocket datagramSocket = new DatagramSocket(6666);

        while (true){
            // Ready to receive the package 
            byte[] bytes = new byte[1024];
            DatagramPacket datagramPacket = new DatagramPacket(bytes,0,bytes.length);

            // disconnect  byebye
            byte[] data = datagramPacket.getData();
            String string = new String(data, 0, data.length);
            System.out.println(string);
            if(string.equals("byebye")){
                break;
            }
        }

        datagramSocket.close();

    }
}