Java study 1:the note of studying Socket which based UDP

1. UDP Concept:

   UDP is the abbreviation of User Datagram protocol, the Chinese name is a Subscriber datagram protocol, is a connectionless Transport layer protocol in the OSI (Open System interconnection, open Systems Interconnect) Reference Model, Provides transaction-oriented, simple unreliable messaging services, and IETF RFC 768 is a formal specification for UDP. The protocol number for UDP in the IP message is 17. (from Baike)

2. UDP Program:

   Because the UDP protocol is a no- Connect protocol,

   (1), each time the delivery of the figures do not need to kidnapped, only need to use the Datagrampacket () to build a good response to the packet on it;

   (2), there is no like TCP serversocket and socket, both sides are initialized with Datagrampacket;

(3), send and receive sent (packets), receive (packet)

Below the password:

*UDP does not have server and client points, but the code one sends an acceptance to the name (it doesn't matter ~ escape)

* After the success of the delivery, the two sides have established a link (virtual), can be mutually developed according to the

1 Importjava.io.IOException;2 ImportJava.net.DatagramPacket;3 ImportJava.net.DatagramSocket;4 Importjava.net.SocketException;5 6  Public classUdpserver {7      Public Static voidMain (string[] args) {8Datagramsocket DGs =NULL;9         Try {Tendgs=NewDatagramsocket (8888); One             //Receive A             byte[] buf=New byte[256]; -             intlength=256; -Datagrampacket dgp=Newdatagrampacket (buf, length); the dgs.receive (DGP); -System.out.println ("Receive from client:" +NewString (buf, 0, length)); -              -             //Send +String str= "Yeah I have receivered~"; -System.out.println (Dgp.getaddress ());//Use last time ' s packet to get the address + System.out.println (Dgp.getport ()); ADatagrampacket dgp_send=NewDatagrampacket (Str.getbytes (), Str.length (), dgp.getaddress (), Dgp.getport ()); at dgs.send (dgp_send); - dgs.close (); -}Catch(SocketException e) { - e.printstacktrace (); -}Catch(IOException e) { - e.printstacktrace (); in}finally{ - dgs.close (); to         } +     } -}

Udpserver

1 ImportJava.net.DatagramPacket;2 ImportJava.net.DatagramSocket;3 Importjava.net.InetAddress;4 5  Public classUdpClient {6      Public Static voidMain (string[] args) {7Datagramsocket DGs =NULL;8         Try {9dgs=NewDatagramsocket ();Ten             //Send->server OneString str= "So Dirty haha~"; ADatagrampacket dgp_send=NewDatagrampacket (Str.getbytes (), 0,str.length (), Inetaddress.getbyname ("localhost"), 8888); - dgs.send (dgp_send); -             //receive from server the             byte[] buf=New byte[256]; -Datagrampacket dgp2_receive=NewDatagrampacket (BUF, 256); - dgs.receive (dgp2_receive); -System.out.println ("Receive from server:" +NewString (buf,0,256)); + dgs.close (); -              +              A}Catch(Exception e) { atSystem.out.println ("Error:" +e); -         } -     } -}

UdpClient

The Send section of the P.s.i:server uses the packet DGP used to receive the packets to get the address and port of the transmitter, and then uses the new datagrampacket to send the numbers.

P.s.ii:datagrampacket conceptions, byte[] used to put the numbers, length used to put a long, simple program so the number of chaotic write (ha

　　

Java study 1:the note of studying Socket which based UDP