Java 25-4 Network programming of UDP protocol transmission ideas

UDP transport

Two classes:Datagramsocket and Datagrampacket(see API)

A: Set up the sending side, the receiving end.

B: Set up the data packet.

C: Call the socket's send receive method.

D: Close the socket.

E: The sending and receiving end is two separate running programs.

UDP transmission-send-side ideas

UDP sends data:
A: Create A Socket send-side object
B: Create a Datagram Package (package the data)
C: Call the Socket object to send a datagram packet
D: Freeing resources (underlying IO stream)

UDP transport-send-side code

1  Public Static voidMain (string[] args)throwsIOException {2         //A: Create A send-side socket object3         //Datagramsocket (): This class represents the socket used to send and receive datagram packets. 4Datagramsocket ds =NewDatagramsocket ();5         6         //B: Create the data and package the data7         //Datagrampacket (byte[] buf, int length, inetaddress address, int port)8         //Create Data9         byte[] bys = "UDP Send Side". GetBytes ();Ten         //Data Length One         intLength =bys.length; A          -         //Create an IP address object -InetAddress address = Inetaddress.getbyname ("172.19.xx.xx"); the          -         //Creating Ports -         intPort = 10010; -          +         //To package the data -Datagrampacket DP =NewDatagrampacket (bys,length,address,port); +          A         //C: Call the Send method of the socket object to send the packet at         //Public void Send (Datagrampacket p) packet for non-connected packet delivery service - Ds.send (DP); -          -         //D: Releasing Resources - ds.close (); -     } in  -}

UDP transmit-receive-side thinking

UDP Receives data:
A: Creating A Socket Receive-side object
B: Create a datagram package to receive data (Create container)
C: Call the Socket object's method to receive the datagram packet
D: Parse packet (byte converted to string) and print in console
E: Freeing Resources

UDP transport-Receive-side code

1  Public classReceivedemo {2      Public Static voidMain (string[] args)throwsIOException {3         //create a receive-side socket object4         //datagramsocket (int port)5Datagramsocket ds =NewDatagramsocket (10010);6 7         //Create a packet (Receive container)8         //Datagrampacket (byte[] buf, int length)9         byte[] Bys =New byte[1000];Ten         intLength =bys.length; OneDatagrampacket DP =Newdatagrampacket (bys, length); A  -         //call the Receive method of the socket object to receive data -         //Public void receive (Datagrampacket p) theDs.receive (DP); //  block type  -  -         //parse the packet and display it in the console -         //get the IP of each other +         //Public inetaddress getaddress () -InetAddress address =dp.getaddress (); +String IP =address.gethostaddress (); A         //Public byte[] GetData (): Get Data buffer at         //public int GetLength (): Gets the actual length of the data -         byte[] Bys2 =Dp.getdata (); -         intLen =dp.getlength (); -String s =NewString (BYS2, 0, Len); -The data passed by SYSTEM.OUT.PRINTLN (IP +) is: "+s); -  in         //Freeing Resources - ds.close (); to     } +}

Note: Because the UDP receiver is a blocking receive, start the receiving end first, and then start the send side.

A diagram of the UDP protocol sending and receiving data:

Java 25-4 Network programming of UDP protocol transmission ideas