import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Main
{
public static void main(String[] args) throws MalformedURLException, IOException
{
/* POBRANIE ŹRÓDŁA STRONY*/
URL url = new URL("http://dziennikustaw.gov.pl/");
BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));
StringBuilder buff = new StringBuilder();
String line;
while((line = in.readLine())!=null)
{
buff.append(line);
buff.append("\n");
}
String str = buff.toString();
in.close();
/* PARSOWANIE ŹRÓDŁA */
Pattern pattNumer = Pattern.compile("<td class=\"c\">([0-9]{1,3})</td>");
Matcher matchNumer = pattNumer.matcher(str);
Pattern pattData = Pattern.compile("<td class=\"c\">([0-9]{4}-[0-9]{2}-[0-9]{2}) ([0-9]{2}:[0-9]{2}:[0-9]{2})<br />"); //br bez spacji
Matcher matchData = pattData.matcher(str);
int i=0;
while(matchNumer.find() && matchData.find() && i<10)
{
System.out.println(matchNumer.group(1)+" "+matchData.group(1)+" "+matchData.group(2));
i++;
}
}
}
W wyniku działania programu otrzymamy:
run: 179 2011-08-30 16:56:35 178 2011-08-29 18:44:54 177 2011-08-26 19:57:05 176 2011-08-26 19:43:00 175 2011-08-25 18:21:44 174 2011-08-23 17:42:06 173 2011-08-22 17:21:39 172 2011-08-19 17:10:41 171 2011-08-18 18:36:57 170 2011-08-18 18:31:47 BUILD SUCCESSFUL (total time: 0 seconds)A więc mamy wszystkie potrzebne dane. Jest to dobry zalążek do pisania większej aplikacji.
import java.sql.Statement;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
public class Main
{
public static void main(String[] args)
{
try
{
Connection sql = DriverManager.getConnection("jdbc:mysql://localhost:3306", "user", "pass"); //ustanowienie połączenia
Statement stat = sql.createStatement(); //utworzenie obiektu statement
stat.execute("USE db"); //wybór bazy
stat.execute("INSERT INTO someTable (txt) VALUES ('Hello World')"); //dodanie rekordu do tabeli
ResultSet rs = stat.executeQuery("SELECT * FROM someTable"); //pobranie danych z bazy
rs.first();
System.out.println(rs.getString("txt")); //wypisanie rekordu na standardowe wyjście
stat.execute("DELETE FROM someTable"); //usunięcie danych z tabeli
stat.close(); //zamknięcie strumieni
sql.close();
}
catch(Exception e)
{
e.printStackTrace();
}
}
}
/*Utworzenie na podanym porcie socketa serwera.*/ ServerSocket serverSocket = new ServerSocket(PORT); /*Oczekiwanie na połączenie i zaakceptowanie*/ Socket clientSocket = serverSocket.accept(); /*Utworzenie strumieni wejściowego i wyjściowego*/ PrintWriter out = new PrintWriter(clientSocket.getOutputStream(),true); BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); /*Wysłanie komunikatu*/ out.println(KOMUNIKAT); /*Oczekiwanie i odebranie komunikatu*/ String input = in.readLine(); /*Zamknięcie strumieniu i socketów*/ out.close(); in.close(); clientSocket.close(); serverSocket.close();
/*Połączenie z serwerem*/ Socket socket = new Socket(HOST, PORT); /*Reszta analogicznie jak w serwerze*/
/* Server.java */
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
public class Server
{
private static final int PORT = 50000;
static boolean flaga = true;
private static ServerSocket serverSocket;
private static Socket clientSocket;
public static void main(String[] args) throws IOException
{
serverSocket = null;
try
{
serverSocket = new ServerSocket(PORT);
}
catch(IOException e)
{
System.err.println("Could not listen on port: "+PORT);
System.exit(1);
}
System.out.print("Wating for connection...");
Thread t = new Thread(new Runnable()
{
public void run()
{
try
{
while(flaga)
{
System.out.print(".");
Thread.sleep(1000);
}
}
catch(InterruptedException ie)
{
//
}
System.out.println("\nClient connected on port "+PORT);
}
});
t.start();
clientSocket = null;
try
{
clientSocket = serverSocket.accept();
flaga = false;
}
catch(IOException e)
{
System.err.println("Accept failed.");
t.interrupt();
System.exit(1);
}
final PrintWriter out = new PrintWriter(clientSocket.getOutputStream(),true);
final BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
t = new Thread(new Runnable()
{
public void run()
{
try
{
Thread.sleep(5000);
while(true)
{
out.println("Ping");
System.out.println(System.currentTimeMillis()+" Ping sent");
String input = in.readLine();
if(input.equals("Pong"))
{
System.out.println(System.currentTimeMillis()+" Pong received");
}
else
{
System.out.println(System.currentTimeMillis()+" Wrong answer");
out.close();
in.close();
clientSocket.close();
serverSocket.close();
break;
}
Thread.sleep(5000);
}
}
catch(Exception e)
{
System.err.println(System.currentTimeMillis()+" Unexpected Error");
}
}
});
t.start();
}
}
/* Client.java */
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
public class Client
{
private static final int PORT = 50000;
private static final String HOST = "localhost";
public static void main(String[] args) throws IOException
{
Socket socket = null;
try
{
socket = new Socket(HOST, PORT);
}
catch(Exception e)
{
System.err.println("Could not connect to "+HOST+":"+PORT);
System.exit(1);
}
final PrintWriter out = new PrintWriter(socket.getOutputStream(),true);
final BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
Thread t = new Thread(new Runnable()
{
public void run()
{
long start = System.currentTimeMillis();
while (true)
{
try
{
String input = in.readLine();
if (input != null)
{
System.out.println(System.currentTimeMillis() + " Server: " + input);
}
if (input.equals("Ping"))
{
if(System.currentTimeMillis()-start>30000)
{
out.println("Pon g");
System.out.println(System.currentTimeMillis() + " Client: Pon g");
break;
}
out.println("Pong");
System.out.println(System.currentTimeMillis() + " Client: Pong");
}
}
catch (IOException ioe)
{
//
}
}
}
});
t.start();
out.close();
in.close();
socket.close();
}
}
Wating for connection.......... Client connected on port 50000 1308645130778 Ping sent 1308645130779 Pong received 1308645135779 Ping sent 1308645135779 Pong received 1308645140780 Ping sent 1308645140780 Pong received 1308645145780 Ping sent 1308645145780 Pong received 1308645150780 Ping sent 1308645150780 Pong received 1308645155781 Ping sent 1308645155781 Wrong answer
1308645130778 Server: Ping 1308645130779 Client: Pong 1308645135779 Server: Ping 1308645135779 Client: Pong 1308645140780 Server: Ping 1308645140780 Client: Pong 1308645145780 Server: Ping 1308645145780 Client: Pong 1308645150780 Server: Ping 1308645150780 Client: Pong 1308645155781 Server: Ping 1308645155781 Client: Pon g
/* Main.java */
import com.db4o.ObjectContainer;
import com.db4o.ObjectServer;
import com.db4o.cs.Db4oClientServer;
import com.db4o.query.Predicate;
import java.util.List;
public class Main
{
static ObjectServer os;
public static void main(String[] args)
{
os = Db4oClientServer.openServer("TestDB", 0);
saveToDB();
loadFromDB();
os.close();
}
public static void saveToDB()
{
ObjectContainer oc = os.openClient();
oc.store(new SomeObject());
oc.close();
}
public static void loadFromDB()
{
ObjectContainer oc = os.openClient();
List list = oc.query(new Predicate()
{
public boolean match(SomeObject so)
{
return so.getClass().getName().equals("SomeObject");
}
});
for(SomeObject so : list)
{
System.out.println(so.x+" "+so.y);
}
oc.close();
}
}
/* SomeObject.java */
import java.util.Random;
public class SomeObject
{
public int x;
public int y;
public SomeObject()
{
Random r = new Random();
x = r.nextInt(10);
y = r.nextInt(100);
}
}
run: 6 58 3 42 6 22 BUILD SUCCESSFUL (total time: 1 second)
ObjectServer os = Db4oClientServer.openServer("TestDB", 0); //otworzenie serwera
ObjectContainer oc = os.openClient(); //otworzenie klienta
oc.store(new SomeObject()); //zapisanie obiektu do bazy
//pobranie obiektów SomeObject z bazy
List list = oc.query(new Predicate()
{
public boolean match(SomeObject so)
{
return so.getClass().getName().equals("SomeObject");
}
});
oc.close(); //zamknięcie klienta
os.close(); //zamknięcie serwera
/* Main.java */
public class Main
{
public static void main(String[] args)
{
Frame f = new Frame("Java - Multithreading");
f.budujOkno();
}
}
/* Frame.java */
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.border.LineBorder;
public class Frame extends JFrame
{
JButton button;
Panel p;
public final static int X = 400;
public final static int Y = 400;
public Frame(String title)
{
super(title);
}
public void budujOkno()
{
addWindowListener(new WindowAdapter()
{
@Override
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
});
setSize(435,487);
setLayout(null);
setVisible(true);
button = new JButton("Przycisk");
button.setLocation(100,420);
button.setSize(200,20);
button.setVisible(true);
button.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
p.changeColor();
}
});
add(button);
p = new Panel();
p.setLocation(10,10);
p.setSize(X,Y);
p.setVisible(true);
p.setBorder(new LineBorder(Color.BLACK));
p.setBackground(Color.white);
add(p);
}
}
/* Panel.java */
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JPanel;
public class Panel extends JPanel
{
public int[] location = null;
private int color = 0;
private Color[] colors = {Color.red, Color.yellow, Color.blue, Color.green};
public Panel()
{
super(null);
}
@Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
Graphics2D g2d = (Graphics2D)g;
if(location != null)
{
g2d.setColor(colors[color]);
g2d.fillOval(location[0]-5, location[1]-5, 10, 10);
g2d.setColor(Color.black);
g2d.drawOval(location[0]-5, location[1]-5, 10, 10);
}
}
public void changeColor()
{
if(color+1 < colors.length)
color++;
else
color = 0;
}
public void setLoc(int x, int y)
{
if(location == null)
location = new int[2];
location[0] = x;
location[1] = y;
}
}
Wszystko ok, program się uruchamia, ale jest coś nie tak. Koło się nie wyświetla bo zmienna location jest null'em. Trzeba obliczyć pozycję koła.
Do tego celu użyjemy pierwszego dziś wątku. Tworzymy klasę anonimową implementującą interface Runnable. Chcemy aby obliczenia wykonywały się do zamknięcia programu więc w metodzie run znajdzie się nieskończona pętla.
Do klasy Frame dodajemy import klasy Random potrzebnej do wylosowania pozycji początkowej, zmienną dla wątku obliczającego, przerwanie wątku w przypadku zamknięcia aplikacji oraz utworzenie nowego wątku.
/* Frame.java */
import java.util.Random;
...
Thread obliczenia;
...
if(obliczenia != null)
obliczenia.interrupt();
...
obliczenia = new Thread(new Runnable()
{
public void run()
{
int kX = 1;
int kY = 1;
int x = (new Random().nextInt((Frame.X - 10) / 10) + 10) * 10;
int y = (new Random().nextInt((Frame.Y - 10) / 10) + 10) * 10;
try
{
while (true)
{
if (kX * 10 + x >= Frame.X)
{
x = Frame.X;
kX *= -1;
}
else if(kX*10 + x <= 0)
{
x = 0;
kX *= -1;
}
else
{
x = kX * 10 + x;
}
if (kY * 10 + y >= Frame.Y)
{
y = Frame.Y;
kY *= -1;
}
else if(kY*10 + y <= 0)
{
y = 0;
kY *= -1;
}
else
{
y = kY * 10 + y;
}
p.setLoc(x, y);
Thread.sleep(10);
}
} catch (InterruptedException e)
{
e.printStackTrace();
}
}
});
obliczenia.start();
...
W tej chwili pozycja jest już obliczana 100 razy na sekundę, natomiast nadal się nie wyświetla. Z tego powodu potrzebny jest wątek odświeżający panel, powiedzmy, 50 razy na sekundę. Ponownie wykorzystamy do tego celu klasę anonimową.
Oto ostateczna wygląd klasy Frame:
/* Frame.java */
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.Random;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.border.LineBorder;
public class Frame extends JFrame
{
JButton button;
Panel p;
public final static int X = 400;
public final static int Y = 400;
Thread obliczenia;
Thread obraz;
public Frame(String title)
{
super(title);
}
public void budujOkno()
{
addWindowListener(new WindowAdapter()
{
@Override
public void windowClosing(WindowEvent e)
{
if(obliczenia != null)
obliczenia.interrupt();
if(obraz != null)
obraz.interrupt();
System.exit(0);
}
});
setSize(435,487);
setLayout(null);
setVisible(true);
button = new JButton("Przycisk");
button.setLocation(100,420);
button.setSize(200,20);
button.setVisible(true);
button.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
p.changeColor();
}
});
add(button);
p = new Panel();
p.setLocation(10,10);
p.setSize(X,Y);
p.setVisible(true);
p.setBorder(new LineBorder(Color.BLACK));
p.setBackground(Color.white);
add(p);
obliczenia = new Thread(new Runnable()
{
@Override
public void run()
{
int kX = 1;
int kY = 1;
int x = (new Random().nextInt((Frame.X - 10) / 10) + 10) * 10;
int y = (new Random().nextInt((Frame.Y - 10) / 10) + 10) * 10;
try
{
while (true)
{
if (kX * 10 + x >= Frame.X)
{
x = Frame.X;
kX *= -1;
}
else if(kX*10 + x <= 0)
{
x = 0;
kX *= -1;
}
else
{
x = kX * 10 + x;
}
if (kY * 10 + y >= Frame.Y)
{
y = Frame.Y;
kY *= -1;
}
else if(kY*10 + y <= 0)
{
y = 0;
kY *= -1;
}
else
{
y = kY * 10 + y;
}
p.setLoc(x, y);
Thread.sleep(10);
}
}
catch (InterruptedException e)
{
//
}
}
});
obliczenia.start();
obraz = new Thread(new Runnable()
{
@Override
public void run()
{
try
{
while(true)
{
p.repaint();
Thread.sleep(20);
}
}
catch(InterruptedException e)
{
//
}
}
});
obraz.start();
}
}
A oto efekt końcowy:
