Java basic knowledge of network programming ——-UDP protocol-based communication example

UDP is an unreliable protocol that establishes a socket on both ends of the communication, which does not establish a persistent communication connection and only sends data unilaterally to the other party without checking the results of the transmission.

UDP protocol-based communication in Java uses the receive and send methods of the Datagramsocket class, but the message needs to be encapsulated by a specific class (Datagrampacket)

The following is an example of a UDP protocol-based communication,

Server-side,

1  PackageUDP;2 3 Importjava.io.IOException;4 ImportJava.net.DatagramPacket;5 ImportJava.net.DatagramSocket;6 7  Public classServer {8     Private Static Final intPORT = 3000;9     //Datagram sizeTen     Private Static Final intData_len = 4096; One     //byte array that accepts network data A     byte[] Inbuff =New byte[Data_len]; -     //Receive Data -     PrivateDatagrampacket Inpacket =NewDatagrampacket (Inbuff, inbuff.length); the     //Send Data -     PrivateDatagrampacket Outpacket; -string[] Books =Newstring[] -     { +"Crazy English", -"Kangxi Dictionary", +"TCP Protocol", A"NiO non-blocking channel" at     }; -      Public voidInit ()throwsIOException { -         Try { -Datagramsocket socket =NewDatagramsocket (PORT); -              for(inti = 0; i < 1000; i++) { -                 //reading data from a socket in socket.receive (inpacket); -System.out.println (Inbuff = =inpacket.getdata ()); toSystem.out.println (NewString (Inbuff, 0, Inpacket.getlength ())); +                  -                 byte[] senddata = books[i% 4].getbytes (); theOutpacket =NewDatagrampacket (SendData, Senddata.length, Inpacket.getaddress (), PORT); * socket.send (outpacket); $             }Panax Notoginseng}Catch(IOException e) { - e.printstacktrace (); the         } +     } A      the      Public Static voidMain (string[] args)throwsIOException { +         NewServer (). Init (); -     } $}

Client

1  PackageUDP;2 3 Importjava.io.IOException;4 ImportJava.net.DatagramPacket;5 ImportJava.net.DatagramSocket;6 Importjava.net.InetAddress;7 ImportJava.util.Scanner;8 9  Public classClient {Ten     Private Static Final intPORT = 3000; One     //Datagram size A     Private Static Final intData_len = 4096; -     Private Static FinalString dest_ip = "127.0.0.1"; -     //byte array that accepts network data the     byte[] Inbuff =New byte[Data_len]; -     //Receive Data -     PrivateDatagrampacket Inpacket =NewDatagrampacket (Inbuff, inbuff.length); -     //Send Data +     PrivateDatagrampacket Outpacket; -      +      Public voidInit ()throwsIOException { A         Try { at             //create a socket using a random port -Datagramsocket socket =NewDatagramsocket (); -Outpacket =NewDatagrampacket (New byte[0], 0, Inetaddress.getbyname (DEST_IP), PORT); -Scanner Scann =NewScanner (system.in); -              while(Scann.hasnextline ()) { -                 byte[] Buff =scann.nextline (). GetBytes (); in outpacket.setdata (buff); - socket.send (outpacket); to socket.receive (inpacket); +System.out.println (NewString (Inbuff, 0, Inpacket.getlength ())); -             } the}Catch(IOException e) { * e.printstacktrace (); $         }Panax Notoginseng     } -      the      Public Static voidMain (string[] args)throwsIOException { +         NewClient (). Init (); A     } the}

Executes the result, starts a server side, starts a client sends a message, the server side outputs the information,

Java basic knowledge of network programming ——-UDP protocol-based communication example