Java Basic Knowledge Enhancement Network programming note 03:UDP UDP protocol send data and receive data

1. UDP protocol to send data and receive data

The UDP protocol sends the data:
　　• Create a Socket object on the sending side
• 　　 Create data and package the data
• 　　 Call the Send method of the socket object to send the packet
　　• Freeing resources

The UDP protocol receives data :

• Create a Socket object on the receiving end
• Create a packet, receive data (Receive container)
• Call the Receive method of the socket object, receive the packet
• parse the packet and display it in the console
• Freeing resources

2. Code implementation

(1) First we write the program of the sending end , as follows:

1  PackageCom.himi.udpDemo;2 3 Importjava.io.IOException;4 ImportJava.net.DatagramPacket;5 ImportJava.net.DatagramSocket;6 Importjava.net.InetAddress;7 Importjava.net.SocketException;8 Importjava.net.UnknownHostException;9 Ten /** One  *  A * UDP protocol sends data: - * 1. Create the socket object on the sending side - * 2. Create the data and package the data the * 3. Call the Send method of the socket object, send the packet - * 4. Releasing Resources -  * -  */ +  Public classUdpsenddemo { -      Public Static voidMain (string[] args)throwsIOException { +         //Create a send-side socket object, where UDP uses the client's socket object class Datagramsocket. A         //Datagramsocket:datagramsocket () atDatagramsocket ds =NewDatagramsocket (); -          -         //Create the data and package the data -         //Datagrampacket: This class represents a datagram packet -         /**Datagrampacket (byte[] buf, int length, inetaddress address, int port) - * * Constructs a datagram package that is used to send packets of length to the specified port number on the specified host.  in         */ -         //Create Data to         byte[] bytes = "The Wind and the world, the wind win." The Mocker of the wind and clouds. Holy Heart tactic, Xuanwu true power ". GetBytes (); +         //IP Address Object -InetAddress address = Inetaddress.getbyname ("49.123.72.145"); the         //Port number *         intPort = 10086; $         //Data PackagingPanax NotoginsengDatagrampacket DP =Newdatagrampacket (Bytes, bytes.length, address, port); -          the              +         //call the Send method of the socket object, send the packet A         //Public void Send (Datagrampacket p) the Ds.send (DP); +          -          $         //Freeing Resources $ ds.close (); -          -     } the  -}

(2) The next implementation is the code of the receiving end , as follows:

1  PackageCom.himi.udpDemo;2 3 Importjava.io.IOException;4 ImportJava.net.DatagramPacket;5 ImportJava.net.DatagramSocket;6 Importjava.net.InetAddress;7 8 /**9  * Ten * UDP protocol receives data: One * 1. Create a socket object on the receiving end A * 2. Create a packet, receive data (Receive container) - * 3. Call the Receive method of the socket object, receive the packet - * 4. Parse the packet and display it in the console the * 5. Releasing Resources -  * -  */ -  +  Public classUdpreceivedemo { -  +      Public Static voidMain (string[] args)throwsIOException { A         //create a socket object on the receiving end at         //datagramsocket (int port): Creates a datagram socket and binds it to the specified port on the local host -Datagramsocket ds =NewDatagramsocket (10086); -          -         //Create a packet, receive data (Receive container) -         //Datagrampacket (byte[] buf, int length) -         byte[] bytes =New byte[1024]; in         intLength =bytes.length; -          toDatagrampacket DP =Newdatagrampacket (bytes, length); +          -         //calls the Receive method of the socket object, receives the packet the         //Public void receive (Datagrampacket p) *Ds.receive (DP);//Blocking Method $         Panax Notoginseng         //parse the packet and display it in the console -         //get the IP of each other the         //Public inetaddress getaddress () +InetAddress address =dp.getaddress (); AString IP =address.gethostaddress (); the          +         //Public byte[] GetData (): Buffer to get data -         //public int GetLength (): Gets the actual length of the data $         byte[] Bys =Dp.getdata (); $         intLen =dp.getlength (); -String s =NewString (bys,0, Len); -          theSYSTEM.OUT.PRINTLN ("Send-side" +ip+ "Data:" +s); -         Wuyi          the         //Freeing Resources - ds.close (); Wu          -                  About  $     } -  -}

(3) Operation:

--Run the receiver first ( similar to the server first )

--and then run the send side, this time, the upper receiver console, will show the sender sent over the data, the effect is as follows:

Java Basic Knowledge Enhancement Network programming note 03:UDP UDP protocol send data and receive data