Java Tutorial/Network/UDP Client
Содержание
Read and write with DatagramPacket
<source lang="java">
import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.InetAddress; public class Main {
public static void main(String[] args) throws Exception {
byte[] ary = new byte[128];
DatagramPacket pack = new DatagramPacket(ary, 128);
// read
DatagramSocket sock = new DatagramSocket(1111);
sock.receive(pack);
String word = new String(pack.getData());
System.out.println("From: " + pack.getAddress() + " Port: " + pack.getPort());
System.out.println(word);
sock.close();
// write
sock = new DatagramSocket();
pack.setAddress(InetAddress.getByName(args[1]));
pack.setData(args[2].getBytes());
pack.setPort(1111);
sock.send(pack);
sock.close();
}
}</source>
Receiving a Datagram
<source lang="java">
import java.net.DatagramPacket; import java.net.DatagramSocket; public class Main {
public static void main(String[] argv) throws Exception {
byte[] inbuf = new byte[256]; // default size
DatagramSocket socket = new DatagramSocket();
DatagramPacket packet = new DatagramPacket(inbuf, inbuf.length);
socket.receive(packet);
int numBytesReceived = packet.getLength();
System.out.println(numBytesReceived);
}
}</source>
Send a Datagram
<source lang="java">
import java.io.IOException; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.InetAddress; import java.net.SocketException; public class Main {
public static void main(String[] argv) throws Exception {
}
public static void senddatagram(InetAddress target, int port, byte[] outbuf, int len) {
try {
DatagramPacket request = new DatagramPacket(outbuf, len, target, port);
DatagramSocket socket = new DatagramSocket();
socket.send(request);
} catch (SocketException e) {
} catch (IOException e) {
}
}
}</source>
Sending a Datagram
<source lang="java">
import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.InetAddress; public class Main {
public static void main(String[] argv) throws Exception {
InetAddress dst = InetAddress.getLocalHost();
int port = 8080;
byte[] outbuf = new byte[1024];
int len = 1024;
DatagramPacket request = new DatagramPacket(outbuf, len, dst, port);
DatagramSocket socket = new DatagramSocket();
socket.send(request);
}
}</source>
UDP Discard Client
<source lang="java">
import java.io.BufferedReader; import java.io.InputStreamReader; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.InetAddress; public class MainClass {
public static void main(String[] args) throws Exception {
InetAddress server = InetAddress.getByName("localhost");
BufferedReader userInput = new BufferedReader(new InputStreamReader(System.in));
DatagramSocket theSocket = new DatagramSocket();
while (true) {
String theLine = userInput.readLine();
if (theLine.equals("."))
break;
byte[] data = theLine.getBytes();
DatagramPacket theOutput = new DatagramPacket(data, data.length, server, 99999);
theSocket.send(theOutput);
}
}
}</source>
UDP Echo Client
<source lang="java">
import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.InetAddress; import java.net.SocketException; public class MainClass {
public static void main(String[] args) throws Exception {
String hostname = "localhost";
InetAddress ia = InetAddress.getByName(hostname);
SenderThread sender = new SenderThread(ia, 1919);
sender.start();
Thread receiver = new ReceiverThread(sender.getSocket());
receiver.start();
}
} class SenderThread extends Thread {
private InetAddress server;
private DatagramSocket socket;
private boolean stopped = false;
private int port;
public SenderThread(InetAddress address, int port) throws SocketException {
this.server = address;
this.port = port;
this.socket = new DatagramSocket();
this.socket.connect(server, port);
}
public void halt() {
this.stopped = true;
}
public DatagramSocket getSocket() {
return this.socket;
}
public void run() {
try {
BufferedReader userInput = new BufferedReader(new InputStreamReader(System.in));
while (true) {
if (stopped)
return;
String theLine = userInput.readLine();
if (theLine.equals("."))
break;
byte[] data = theLine.getBytes();
DatagramPacket output = new DatagramPacket(data, data.length, server, port);
socket.send(output);
Thread.yield();
}
}
catch (IOException ex) {
System.err.println(ex);
}
}
} class ReceiverThread extends Thread {
DatagramSocket socket;
private boolean stopped = false;
public ReceiverThread(DatagramSocket ds) throws SocketException {
this.socket = ds;
}
public void halt() {
this.stopped = true;
}
public void run() {
byte[] buffer = new byte[65507];
while (true) {
if (stopped)
return;
DatagramPacket dp = new DatagramPacket(buffer, buffer.length);
try {
socket.receive(dp);
String s = new String(dp.getData(), 0, dp.getLength());
System.out.println(s);
Thread.yield();
} catch (IOException ex) {
System.err.println(ex);
}
}
}
}</source>
UDP Time Client
<source lang="java">
import java.net.DatagramSocket; import java.net.InetSocketAddress; import java.net.SocketAddress; import java.nio.ByteBuffer; import java.nio.ByteOrder; import java.nio.channels.DatagramChannel; public class UDPTimeClient {
public static void main(String[] args) throws Exception {
DatagramChannel channel = DatagramChannel.open();
// port 0 selects any available port
SocketAddress address = new InetSocketAddress(0);
DatagramSocket socket = channel.socket();
socket.setSoTimeout(5000);
socket.bind(address);
SocketAddress server = new InetSocketAddress("time.nist.gov", 37);
ByteBuffer buffer = ByteBuffer.allocate(8192);
// time protocol always uses big-endian order
buffer.order(ByteOrder.BIG_ENDIAN);
// Must put at least one byte of data in the buffer;
// it doesn"t matter what it is.
buffer.put((byte) 65);
buffer.flip();
channel.send(buffer, server);
buffer.clear();
buffer.put((byte) 0).put((byte) 0).put((byte) 0).put((byte) 0);
channel.receive(buffer);
buffer.flip();
long secondsSince1970 = buffer.getLong();
System.out.println(secondsSince1970);
channel.close();
}
}</source>
User Datagram Protocol Programming
<source lang="java">
import java.io.IOException; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.InetAddress; public class Main {
final private static int DAYTIME_PORT = 13;
public static void main(String args[]) throws IOException {
String host = args[0];
byte message[] = new byte[256];
InetAddress address = InetAddress.getByName(host);
System.out.println("Checking at: " + address);
DatagramPacket packet = new DatagramPacket(message, message.length, address, DAYTIME_PORT);
DatagramSocket socket = new DatagramSocket();
socket.send(packet);
packet = new DatagramPacket(message, message.length);
socket.receive(packet);
String time = new String(packet.getData());
System.out.println(time);
socket.close();
}
}</source>
