Shulou(Shulou.com)06/02 Report--

This article will explain in detail how to use UDP protocol to transmit data in Android. The editor thinks it is very practical, so I share it for you as a reference. I hope you can get something after reading this article.

1. Using UDP protocol to transfer data

The UDP protocol is unreliable, and it is impossible to determine whether it is received by the receiver after the packet is sent.

Write Server in Java as follows

Package com.umgsai.server;import java.net.DatagramPacket;import java.net.DatagramSocket;import java.util.Calendar;import java.util.Date;public class Server {static Date date Public static void main (String [] args) {while (true) {try {/ / create a DatagramSocket object and specify the listening port number DatagramSocket socket = new DatagramSocket (4572); byte data [] = new byte [1024] / / create an empty DatagramPacket object DatagramPacket packet = new DatagramPacket (data, data.length); / / use the receive method to receive data sent by the client socket.receive (packet) String result = new String (packet.getData (), packet.getOffset (), packet.getLength ()); date = Calendar.getInstance (). GetTime (); System.out.println (date) System.out.println ("result--- >" + result); socket.close ();} catch (Exception e) {e.printStackTrace ();}}

The client is written in Android

Interface activity_main.xml

The operation of connecting to the network in the Android4.0+ operating system cannot be done in the main thread.

Public class MainActivity extends Activity {private Button sendMessage = null; @ Override protected void onCreate (Bundle savedInstanceState) {super.onCreate (savedInstanceState); setContentView (R.layout.activity_main); sendMessage = (Button) findViewById (R.id.sendMessage); sendMessage.setOnClickListener (new clientListener ()) } class clientListener implements OnClickListener {@ Override public void onClick (View v) {HandlerThread handlerThread = new HandlerThread ("handler_Thread"); handlerThread.start (); ClientHandler clientHandler = new ClientHandler (handlerThread.getLooper ()); Message msg = clientHandler.obtainMessage () Bundle bundle = new Bundle (); msg.setData (bundle); / / send msg to the target object, that is, the Handler object msg.sendToTarget () that generates the msg object }} class ClientHandler extends Handler {public ClientHandler () {} public ClientHandler (Looper looper) {super (looper);} @ Override public void handleMessage (Message msg) {super.handleMessage (msg); Bundle bundle = msg.getData () Try {/ / first create a DatagramSocket object DatagramSocket socket = new DatagramSocket (4572); / / create an InetAddree InetAddress serverAddress = InetAddress.getByName ("192.168.77.215") String str = "hello"; byte data [] = str.getBytes () / / create a DatagramPacket object and specify which address in the network to send this packet to, and the port number DatagramPacket packet = new DatagramPacket (data, data.length, serverAddress, 4572) / / call the send method of the socket object to send data socket.send (packet); socket.close (); Toast.makeText (MainActivity.this, "data sent", Toast.LENGTH_SHORT) .show () } catch (Exception e) {/ / TODO: handle exception e.printStackTrace ();}

Permissions required by the client

TCP is a reliable protocol.

TCPServer.java

Public class TCPServer {public static void main (String [] args) throws IOException {ServerSocket listen = new ServerSocket (5050); Socket server = listen.accept (); InputStream in = server.getInputStream (); OutputStream out = server.getOutputStream (); char c = (char) in.read (); System.out.println ("received:" + c) Out.write ('s'); out.close (); in.close (); server.close (); listen.close ();}}

TCPClient.java

Public class TCPClient {public static void main (String [] args) throws IOException {Socket client = new Socket ("127.0.0.1", 5050); InputStream in = client.getInputStream (); OutputStream out = client.getOutputStream (); out.write ('c'); char c = (char) in.read () System.out.println ("receive:" + c); out.close (); in.close (); client.close ();}}

Socket programming has nothing to do with the Android operating system and uses classes in the Java.net package.

When doing network programming in Android, you should be careful not to put the code that connects to the network into the main thread.

PS: when displaying Toast in a non-UI thread, write as follows

Looper.prepare (); Toast.makeText (MainActivity.this, result, Toast.LENGTH_SHORT). Show (); Looper.loop ()

Examples of TCP provided in the Mars video are as follows

Server end

Class ServerThread extends Thread {public void run () {/ / declare a ServerSocket object ServerSocket serverSocket = null; try {/ / create a ServerSocket object and have this Socket listen on port 4567 serverSocket = new ServerSocket (4567) / / call the accept () method of ServerSocket to accept the request sent by the client: Socket socket = serverSocket.accept (); / / get the InputStream object InputStream inputStream = socket.getInputStream () from Socket; byte buffer [] = new byte [1024x4] Int temp = 0; / / read the data sent by the client from InputStream while ((temp = inputStream.read (buffer))! =-1) {System.out.println (new String (buffer,0,temp) }} catch (IOException e) {/ / TODO Auto-generated catch block e.printStackTrace ();} finally {try {serverSocket.close () } catch (IOException e) {/ / TODO Auto-generated catch block e.printStackTrace ();}}

Client end

Public class TCPClient {public static void main (String [] args) {try {/ / create a Socket object that specifies the server-side IP address and port number Socket socket = new Socket ("192.168.1.104", 4567) / / use InputStream to read the file on the hard disk InputStream inputStream = new FileInputStream ("f://file/words.txt"); / / get OutputStream OutputStream outputStream = socket.getOutputStream () from Socket; byte buffer [] = new byte [4x1024] Int temp = 0; / / take out the data from InputStream and write it to OutputStream while ((temp = inputStream.read (buffer))! =-1) {outputStream.write (buffer, 0, temp) } outputStream.flush ();} catch (Exception e) {/ / TODO Auto-generated catch block e.printStackTrace ();}

The following exception is thrown during debugging, which has not been resolved yet

Java.net.SocketException: Connection reset

At java.net.SocketInputStream.read (Unknown Source)

At java.net.SocketInputStream.read (Unknown Source)

At java.net.SocketInputStream.read (Unknown Source)

At com.umgsai.server.TCPServer.main (TCPServer.java:25)

This is the end of this article on "how to transfer data using UDP protocol in Android". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, please share it for more people to see.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.