byte[] ip4 = {195, 113, 194, 135}; // adresa IPv4
try {
InetAddress ia = InetAddress.getByAddress(ip4);
InetAddress ia2 = InetAddress.getByName("195.113.194.135");
InetAddress ia3 = InetAddress.getByName("akela.mendelu.cz");
} catch (UnknownHostException e) {
e.printStackTrace();
}
try {
InetAddress ia = InetAddress.getByName("akela.mendelu.cz");
InetSocketAddress isa = new InetSocketAddress(ia, 80);
InetSocketAddress isa2 = new InetSocketAddress("akela.mendelu.cz", 80);
} catch (UnknownHostException e) {
e.printStackTrace();
}
byte[] data = {0, 1, 2, 5, 19, 28}; // data, která chceme přenést
DatagramPacket dgp1 = new DatagramPacket(data, data.length);
DatagramPacket dgp2 = null;
DatagramPacket dgp3 = null;
try {
dgp2 = new DatagramPacket(data, data.length, InetAddress.getByName("pocitac.domena.cz"), 12345);
dgp3 = new DatagramPacket(data, data.length, new InetSocketAddress("pocitac.domena.cz", 12345));
}
catch (SocketException ex) {
ex.printStackTrace();
}
catch (UnknownHostException ex) {
ex.printStackTrace();
}
try {
DatagramSocket sock1 = new DatagramSocket();
sock1.send(dgp1); // chyba (NullPointerException) – datagram ani socket nemá cíl. adresu a port
sock1.send(dgp2); // funguje
DatagramSocket sock2 = new DatagramSocket(55555); // 55555 je číslo portu na lokálním stroji
sock2.connect(InetAddress.getByName("pocitac.domena.org"), 44444);
sock2.send(dgp1); // funguje
sock2.send(dgp2); // chyba – výjimka kvůli neshodě adres
}
catch (IOException ex) {
ex.printStackTrace();
}
try {
DatagramSocket sock = new DatagramSocket(20000);
DatagramPacket dgp = new DatagramPacket(new byte[1000], 1000);
sock.setSoTimeout(600000); // timeout 10 minut
while (true) {
sock.receive(dgp);
sock.send(dgp);
}
} catch (Exception e) {
...
}
import java.io.*;
class Osoba implements Serializable {
private String jmeno;
private int vek;
public Osoba(String jmeno, int vek) {
this.jmeno = jmeno;
this.vek = vek;
}
public String getJmeno() {
return jmeno;
}
public int getVek() {
return vek;
}
}
public class Main {
public static void main(String[] args) {
Osoba o = new Osoba("Jana", 40);
ByteArrayOutputStream baou = new ByteArrayOutputStream();
try {
ObjectOutputStream oos = new ObjectOutputStream(baou);
oos.writeObject(o);
oos.flush();
oos.close();
byte[] pole = baou.toByteArray(); // V tomto poli bajtů je uložen objekt třídy Osoba.
// Pole "pole" odešleme po síti. Příjemce jej konvertuje zpět na objekt následujícím způsobem:
ByteArrayInputStream bais = new ByteArrayInputStream(pole);
ObjectInputStream ois = new ObjectInputStream(bais);
Object obj = ois.readObject();
if (obj instanceof Osoba) {
Osoba o2 = (Osoba) obj;
System.out.println(o2.getJmeno() + ", " + o2.getVek() + " let");
}
} catch (IOException | ClassNotFoundException e) {
throw new RuntimeException(e);
}
}
}
try {
Socket sock = new Socket("akela.mendelu.cz", 80); // připojení
BufferedReader br = new BufferedReader(new InputStreamReader(sock.getInputStream()));
BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(sock.getOutputStream()));
bw.write(request); // zapíšeme předem připravený požadavek (jeho příprava není součástí tohoto příkladu)
bw.flush(); // vyprázdnění (tzn. odeslání) bufferu
String line = br.readLine();
// dokud jsou data, opakuj
while (line != null) {
System.out.println(line); // platná data vypisuj
line = br.readLine();
}
sock.close(); // zavření socketu
}
catch (UnknownHostException ex) {
...
}
catch (IOException ex) {
...
}
boolean quit = false;
try {
ServerSocket ss = new ServerSocket(22222);
while (!quit) {
final Socket sock = ss.accept();
Thread t = new Thread() {
public void run() {
try {
InputStream is = sock.getInputStream();
OutputStream os = sock.getOutputStream();
...
sock.close();
} catch (IOException e) {
...
}
}
};
t.setDaemon(true);
t.start();
}
} catch (Exception e) {
...
}
public enum Barva {
CERVENA, ZELENA, MODRA, ZLUTA
}
import java.io.Serializable;
public class Figurka implements Serializable {
final Barva barva;
int x, y;
public Figurka(Barva barva, int x, int y) {
this.barva = barva;
this.x = x;
this.y = y;
}
@Override
public String toString() {
return "Figurka{" +
"barva=" + barva +
", x=" + x +
", y=" + y +
'}';
}
}
import java.io.*;
import java.net.*;
public class Receiver implements Runnable {
int localPort;
public Receiver(int localPort) {
this.localPort = localPort;
}
@Override
public void run() {
ObjectInputStream ois;
ServerSocket servSock = null;
try {
servSock = new ServerSocket(localPort);
Socket sock = servSock.accept();
ois = new ObjectInputStream(sock.getInputStream());
Object o = ois.readObject();
System.out.println(o);
ois.close();
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
}
import java.io.*;
import java.net.*;
public class Sender implements Runnable {
Object o;
String hostName;
int destPort;
public Sender(Object o, String hostName, int destPort) {
this.o = o;
this.hostName = hostName;
this.destPort = destPort;
}
@Override
public void run() {
ObjectOutputStream oos;
try {
Socket sock = new Socket(hostName, destPort);
oos = new ObjectOutputStream(sock.getOutputStream());
oos.writeObject(o);
oos.flush();
oos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
public class Main {
public static void main(String[] args) {
final int port = 55555;
Figurka figurka = new Figurka(Barva.ZELENA, 1, 5);
Thread prijemce = new Thread(new Receiver(port));
prijemce.start();
Thread odesilatel = new Thread(new Sender(figurka, "localhost", port));
odesilatel.start();
}
}
try {
URL url = new URL("http://www.pef.mendelu.cz/");
HttpURLConnection con = (HttpURLConnection) url.openConnection();
System.out.println("Response code: " + con.getResponseCode());
System.out.println("Content type: " + con.getContentType());
BufferedReader br = new BufferedReader(new InputStreamReader(con.getInputStream()));
String s = br.readLine();
while (s != null) {
System.out.println(s);
s = br.readLine();
}
con.disconnect();
} catch (Exception e) {
...
}
double x = Math.cos(Math.PI * Math.pow(r, 2));
import static java.lang.Math.*; ... double x = cos(PI * pow(r, 2));