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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
 1 // test IP
 2 public class TestInetAddress {
 3     public static void main(String[] args) {
 4         try {
 5             // Look up the local address 
 6             InetAddress inetAddress = InetAddress.getByName("127.0.0.1");
 7             System.out.println(inetAddress);
 8             InetAddress localhost = InetAddress.getByName("localhost");
 9             System.out.println(localhost);
10             InetAddress localHost = InetAddress.getLocalHost();
11             System.out.println(localHost);
12 
13             // Check the website ip Address 
14             InetAddress inetAddress1 = InetAddress.getByName("www.baidu.com");
15             System.out.println(inetAddress1);
16 
17             // Common methods 
18             System.out.println(inetAddress1.getHostAddress());//ip
19             System.out.println(inetAddress1.getHostName());// domain name , Or your own name 
20         } catch (UnknownHostException e) {
21             e.printStackTrace();
22         }
23     }
24 }

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
 1 // port 
 2 public class TestInetSocketAddress {
 3     public static void main(String[] args) {
 4         InetSocketAddress socketAddress = new InetSocketAddress("127.0.0.1", 8080);
 5         System.out.println(socketAddress);
 6 
 7         System.out.println(socketAddress.getAddress());
 8         System.out.println(socketAddress.getHostName());// Address 
 9         System.out.println(socketAddress.getPort());// port 
10     }
11 }

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

 1 // Server side 
 2 public class TcpServerDemo01 {
 3     public static void main(String[] args) {
 4         ServerSocket serverSocket = null;
 5         Socket accept=null;
 6         InputStream is=null;
 7         ByteArrayOutputStream baos=null;
 8         try {
 9             //1. You have to have an address 
10             serverSocket = new ServerSocket(9999);
11 
12             while (true){
13                 //2. Wait for the client to connect 
14                 accept = serverSocket.accept();
15                 //3. Read the message from the client 
16                 is = accept.getInputStream();
17 
18                 // Pipe flow 
19                 baos = new ByteArrayOutputStream();
20                 byte[] bytes = new byte[1024];
21                 int len;
22                 while ((len=is.read(bytes))!=-1){
23                     baos.write(bytes,0,len);
24                 }
25                 System.out.println(baos.toString());
26             }
27 
28         } catch (IOException e) {
29             e.printStackTrace();
30         }finally {
31             // Closed flow 
32             try {
33                 baos.close();
34             } catch (IOException e) {
35                 e.printStackTrace();
36             }
37             try {
38                 is.close();
39             } catch (IOException e) {
40                 e.printStackTrace();
41             }
42             try {
43                 accept.close();
44             } catch (IOException e) {
45                 e.printStackTrace();
46             }
47             try {
48                 serverSocket.close();
49             } catch (IOException e) {
50                 e.printStackTrace();
51             }
52 
53         }
54     }
55 }
 1 // client 
 2 public class TcpClientDemo01 {
 3     public static void main(String[] args) {
 4         Socket socket=null;
 5         OutputStream os=null;
 6 
 7         try {
 8             //1. Until the server's address 
 9             InetAddress serverIP= InetAddress.getByName("127.0.0.1");
10             int port=9999;
11             //2. Create a socker Connect 
12             try {
13                 socket = new Socket(serverIP,port);
14                 //3. Send a message  IO flow 
15                 os = socket.getOutputStream();
16                 os.write("Hello".getBytes());
17             } catch (IOException e) {
18                 e.printStackTrace();
19             }
20 
21 
22         } catch (UnknownHostException e) {
23             e.printStackTrace();
24         }finally {
25             try {
26                 os.close();
27             } catch (IOException e) {
28                 e.printStackTrace();
29             }
30             try {
31                 socket.close();
32             } catch (IOException e) {
33                 e.printStackTrace();
34             }
35         }
36     }
37 }

TCP Upload files

 1 // Server side 
 2 public class TcpServerDemo02 {
 3     public static void main(String[] args) throws Exception{
 4         //1. Create services 
 5         ServerSocket serverSocket = new ServerSocket(9000);
 6         //2. Listen for client connections 
 7         Socket accept = serverSocket.accept();// Blocking monitoring , Will be waiting for the client to connect 
 8         //3. Get input stream 
 9         InputStream is = accept.getInputStream();
10 
11         //4. File output 
12         FileOutputStream fos = new FileOutputStream("receive.jpg");
13         byte[] by = new byte[1024];
14         int len;
15         while ((len=is.read(by))!=-1){
16             fos.write(by,0,len);
17         }
18 
19         // Inform the client that I have finished receiving 
20         OutputStream os = accept.getOutputStream();
21         os.write(" End of reception ".getBytes());
22 
23         os.close();
24         fos.close();
25         is.close();
26         accept.close();
27         serverSocket.close();
28     }
29 }
 1 // client 
 2 public class TcpClientDemo02 {
 3     public static void main(String[] args) throws Exception{
 4         //1. Create a socket Connect 
 5         Socket socket = new Socket(InetAddress.getByName("127.0.0.1"),9000);
 6         //2. Create an output stream 
 7         OutputStream os = socket.getOutputStream();
 8 
 9         //3. Read the file 
10         FileInputStream fis = new FileInputStream("D:\\WorkSpace\\JavaSE\\ Basic grammar \\111.png");
11         //4. Write a document 
12         byte[] by = new byte[1024];
13         int len;
14         while ((len=fis.read(by))!=-1){
15             os.write(by,0,len);
16         }
17 
18         // Notification server , I've finished the transmission 
19         socket.shutdownOutput();
20 
21         // Confirm that the server has received , To disconnect 
22         InputStream is = socket.getInputStream();
23         ByteArrayOutputStream baos = new ByteArrayOutputStream();
24 
25         byte[] bytes = new byte[1024];
26         int leng;
27         while ((leng=is.read(bytes))!=-1){
28             baos.write(bytes,0,leng);
29         }
30         System.out.println(baos.toString());
31 
32         baos.close();
33         is.close();
34         os.close();
35         fis.close();
36         socket.close();
37     }
38 }

UDP message sending

 1 // The sender 
 2 public class UdpClientDemo01 {
 3     public static void main(String[] args) throws Exception{
 4         //1. Build a Socket
 5         DatagramSocket datagramSocket = new DatagramSocket();
 6 
 7         //2. Build a package 
 8         String msg=" How do you do , The server !";
 9         InetAddress localhost = InetAddress.getByName("localhost");
10         int port = 9090;
11 
12         // data 、 The length of the data starts with 、 To whom 
13         DatagramPacket datagramPacket = new DatagramPacket(msg.getBytes(),0,msg.getBytes().length,localhost,port);
14 
15         // Send package 
16         datagramSocket.send(datagramPacket);
17 
18         //4. Closed flow 
19         datagramSocket.close();
20     }
21 }
 1 // The receiving party 
 2 public class UdpServerDemo01 {
 3     public static void main(String[] args) throws Exception{
 4         // Open ports 
 5         DatagramSocket datagramSocket = new DatagramSocket(9090);
 6         // receive data 
 7         byte[] bytes = new byte[1024];
 8         DatagramPacket datagramPacket = new DatagramPacket(bytes,0,bytes.length);
 9 
10         datagramSocket.receive(datagramPacket);// Blocking reception 
11 
12         System.out.println(datagramPacket.getAddress());
13         System.out.println(new String(datagramPacket.getData(),0,datagramPacket.getLength()));
14     }
15 }

UDP Chat to achieve

 1 // The sender 
 2 public class UdpSenderDemo01 {
 3     public static void main(String[] args) throws Exception{
 4 
 5         DatagramSocket datagramSocket = new DatagramSocket(8888);
 6 
 7         // Prepare the data : The console reads System.in
 8         BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
 9 
10         while (true){
11             String data=reader.readLine();
12             byte[] bytes = data.getBytes();
13             DatagramPacket datagramPacket = new DatagramPacket(bytes,0,bytes.length,new InetSocketAddress("localhost",6666));
14             datagramSocket.send(datagramPacket);
15             if(bytes.equals("byebye")){
16                 break;
17             }
18         }
19         datagramSocket.close();
20     }
21 }
 1 // The receiving party 
 2 public class UdpReceiveDemo01 {
 3     public static void main(String[] args) throws Exception{
 4         DatagramSocket datagramSocket = new DatagramSocket(6666);
 5 
 6         while (true){
 7             // Ready to receive the package 
 8             byte[] bytes = new byte[1024];
 9             DatagramPacket datagramPacket = new DatagramPacket(bytes,0,bytes.length);
10 
11             // disconnect  byebye
12             byte[] data = datagramPacket.getData();
13             String string = new String(data, 0, data.length);
14             System.out.println(string);
15             if(string.equals("byebye")){
16                 break;
17             }
18         }
19 
20         datagramSocket.close();
21 
22     }
23 }

 

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