วันนี้เราจะมาเขียนโปรแกรม Recursive กันนะครับ

koch snowflake in JAVA

import java.awt.Graphics;
import java.awt.Graphics2D;

import javax.swing.JFrame;


public class KochSnowFlake extends JFrame
{ 
	private static final long serialVersionUID = 1L;

	int num=1;

	public KochSnowFlake()
	{
		setSize(600, 600);
		setDefaultCloseOperation(EXIT_ON_CLOSE);
		setVisible(true);
		
		Thread t= new Thread(new Runnable()
		{
			
			@Override
			public void run()
			{
				while(true)
				{
					for(int i=1;i<= 10;i++)
					{
						try
						{
							Thread.sleep(6000 );
						} catch (InterruptedException e)
						{
							// TODO Auto-generated catch block
							e.printStackTrace();
						}
						num=i;
						
						repaint();
						
					}
				}
				
			}
		});
		t.start();
		
	}

	public void paint(Graphics g)
	{
		super.paint(g);
		Graphics2D gg=(Graphics2D)g;
		
		Vector now= new Vector(getWidth() / 5.0, getHeight()/3.0*2.0);
		Vector dir_with_size= new Vector(getWidth() /5.0*3.0, 0);
		dir_with_size= dir_with_size.rotate(Math.PI/3);
		createSnowFlake( gg ,  now, dir_with_size, num);
		
		now= now.add(dir_with_size);
		dir_with_size= dir_with_size.rotate(-Math.PI/3*2);
		createSnowFlake( gg ,  now, dir_with_size, num);
		
		now= now.add(dir_with_size);
		dir_with_size= dir_with_size.rotate(-Math.PI/3*2);
		createSnowFlake( gg ,  now, dir_with_size, num);
		
	}
	public void createSnowFlake(Graphics2D g , Vector now,Vector dir_with_size,int n)
	{
		if(n==0) return;
		
		if(n==1)
		{
			Vector a,d;
			a = now;
			d = dir_with_size.add(now);
			g.drawLine((int)a.x,(int)a.y, (int)d.x,(int)d.y);
			return;
		}
		Vector a,b,c,d;
		a = now;
		b = dir_with_size.mul(1.0/3.0).add(now);
		
		c = dir_with_size.mul(2.0/3.0).add(now);
		d = dir_with_size.mul(1).add(now);
		
		
		Vector dir_with_size2= dir_with_size.rotate(Math.PI /3.0).mul(1.0/3.0);
		Vector start3 = dir_with_size2.add(b);
		Vector dir_with_size3= c.sub(start3)  ;

		createSnowFlake( g ,  b, dir_with_size2, n-1);
		createSnowFlake( g ,  start3, dir_with_size3, n-1);

		createSnowFlake( g ,  a, dir_with_size.mul(1.0/3.0), n-1);
		createSnowFlake( g ,  c, dir_with_size.mul(1.0/3.0), n-1);
		
	}
	
	public static void main(String[] args)
	{
		new KochSnowFlake();

	}

}


class Vector
{
	public double x,y;
	public Vector(){}
	public Vector (double xx,double yy)
	{
		x=xx;
		y=yy;
	}
	public Vector rotate(double angle)
	{
		double xx,yy;
		double c = Math.cos(angle);
		double s = Math.sin(angle);
		
		xx = x*c + y*s;
		yy = -x*s + y*c;
		
		
		return new Vector(xx,yy);
	}
	
	public Vector mul(double m)
	{
		return new Vector(x*m,y*m);
	}
	
	public Vector add(Vector v)
	{
		return new Vector(x+v.x,y+v.y);
	}
	public Vector sub(Vector v)
	{
		return new Vector(x-v.x,y-v.y);
	}
}

  int count = 0;
        Image img;
        Random rand = new Random();
 for (int ii = 0; ii < 1000; ii++)
            {
                img = new Bitmap(120, 70);
                Graphics g = Graphics.FromImage(img);

                int i = rand.Next(10000);
                String s = "" + (char)(rand.Next(26) + 65);
                s += (char)(rand.Next(26) + 65);
                s += i;

                g.DrawString(s, new Font("Tahoma", 22, FontStyle.Regular), Brushes.Black, 5, 10);

                for (int j = 0; j < 10; j++)
                {
                    int x1, y1, x2, y2;
                    x1 = rand.Next(26);
                    x2 = rand.Next(26) + 94;
                    y1 = rand.Next(70);
                    y2 = rand.Next(70);

                    g.DrawLine(new Pen(Color.FromArgb(rand.Next(70), rand.Next(70), rand.Next(70))), x1, y1, x2, y2);

                }

                g.Flush();
                img.Save("D://capcha//" + count + ".PNG", System.Drawing.Imaging.ImageFormat.Png);


                String path, key, phone;
                // id = Int32.Parse(this.textBox_id.Text);
                path = count + ".PNG";
                key = s;


                string cs = @"server=localhost;userid=root;password=1234;database=yyy";
                MySqlConnection conn = new MySqlConnection(cs);

                String sql = @"INSERT INTO capcha VALUES (0, '" + path + "','" + key + "' )";
                MySqlCommand comm = new MySqlCommand(sql, conn);
                conn.Open();
                comm.ExecuteNonQuery();


                conn.Close();

                count++;
            }

import java.awt.Graphics;
import java.awt.image.BufferedImage;
import javax.swing.JPanel;
public class ImagePanel extends JPanel{
	BufferedImage  img;
	public ImagePanel(){}
	public void setImage(BufferedImage i){
		img = i;
		repaint();
	}
	public BufferedImage getImage(){
		return img;
	}
	public void paint(Graphics g){
		g.drawImage(img, 0, 0,this.getWidth(),this.getHeight(), this);
	}
}

import java.awt.EventQueue;

import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.filechooser.FileFilter;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.UIManager;

import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.sql.*;

public class InsertProduct extends JFrame
{

	private JPanel contentPane;
	private JTextField txt_name;
	private JTextField txt_price;
	private ImagePanel imagePanel;

	/**
	 * Launch the application.
	 */
	public static void main(String[] args)
	{
		try
		{
			UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
		} catch (Exception e){}
		EventQueue.invokeLater(new Runnable()
		{
			public void run()
			{
				try
				{
					InsertProduct frame = new InsertProduct();
					frame.setVisible(true);
				} catch (Exception e)
				{
					e.printStackTrace();
				}
			}
		});
	}
	public InsertProduct()
	{
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setBounds(100, 100, 450, 300);
		contentPane = new JPanel();
		contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
		setContentPane(contentPane);
		contentPane.setLayout(null);

		imagePanel = new ImagePanel();
		imagePanel.setBounds(10, 11, 248, 240);
		contentPane.add(imagePanel);

		JButton btnBrowse = new JButton("browse image");
		btnBrowse.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent arg0)
			{
				JFileChooser fc = new JFileChooser("c://");
				fc.setFileFilter(new JPEGImageFileFilter());
				int res = fc.showOpenDialog(null);
				if (res == JFileChooser.APPROVE_OPTION)
				{
					File file = fc.getSelectedFile();
					// this.
					try
					{
						imagePanel.setImage(ImageIO.read(file));
					} catch (IOException e)
					{
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
				}
			}
		});
		btnBrowse.setBounds(268, 11, 156, 23);
		contentPane.add(btnBrowse);

		JLabel lblProductName = new JLabel("product name");
		lblProductName.setBounds(268, 51, 102, 14);
		contentPane.add(lblProductName);

		txt_name = new JTextField();
		txt_name.setBounds(268, 74, 156, 23);
		contentPane.add(txt_name);
		txt_name.setColumns(10);

		JLabel lblPricePerUnit = new JLabel("price per unit");
		lblPricePerUnit.setBounds(268, 108, 102, 14);
		contentPane.add(lblPricePerUnit);

		txt_price = new JTextField();
		txt_price.setColumns(10);
		txt_price.setBounds(268, 131, 156, 23);
		contentPane.add(txt_price);

		JButton btn_insert = new JButton("Insert");
		btn_insert.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent e)
			{
				try
				{
					Connection con = null;
					Class.forName("com.mysql.jdbc.Driver");
					con = (Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/yyy", "root", "1234");

					Class.forName("com.mysql.jdbc.Driver");

					String price = txt_price.getText();
					String name = txt_name.getText();

					String insert = "INSERT INTO product(id,name,price_per_unit,image) " + " VALUES (0,?,?,?)";

					PreparedStatement preparedStmt = con.prepareStatement(insert);
					ByteArrayOutputStream buff = new ByteArrayOutputStream();
					ImageIO.write(imagePanel.getImage(), "PNG", buff);
					byte[] buff_temp = buff.toByteArray();
					ByteArrayInputStream inBuff = new ByteArrayInputStream(buff_temp);

					preparedStmt.setString(1, name);
					preparedStmt.setString(2, price);
					preparedStmt.setBinaryStream(3, inBuff, buff_temp.length);

					preparedStmt.execute();
					System.out.println("finish");
					con.close();
				} catch (Exception ee)
				{
					ee.printStackTrace();
				}
			}
		});
		btn_insert.setBounds(269, 185, 89, 23);
		contentPane.add(btn_insert);
	}
}
class JPEGImageFileFilter extends FileFilter implements java.io.FileFilter{
	public boolean accept(File f){
		if (f.getName().toLowerCase().endsWith(".jpeg"))
			return true;
		if (f.getName().toLowerCase().endsWith(".jpg"))
			return true;
		if (f.isDirectory())
			return true;
		return false;
	}
	public String getDescription()
	{
		return "JPEG files";
	}
}

ดึงข้อมูลพ้อมรูปมาแสดง

import java.awt.image.BufferedImage;
import javax.swing.JPanel;
import javax.swing.JLabel;
public class ProductPanel extends JPanel
{
public ProductPanel()
{
setLayout(null);
imagePanel = new ImagePanel();
imagePanel.setBounds(0, 0, 223, 109);
add(imagePanel);
label_id = new JLabel("New label");
label_id.setBounds(322, 9, 118, 26);
add(label_id);
label_name = new JLabel("New label");
label_name.setBounds(322, 46, 118, 26);
add(label_name);
label_price = new JLabel("New label");
label_price.setBounds(322, 83, 118, 26);
add(label_price);
lblUd = new JLabel("id");
lblUd.setBounds(233, 9, 62, 26);
add(lblUd);
lblName = new JLabel("name");
lblName.setBounds(233, 46, 62, 26);
add(lblName);
lblPricePerUnit = new JLabel("price per unit");
lblPricePerUnit.setBounds(233, 83, 79, 26);
add(lblPricePerUnit);
}

public void setParam(int id, String name, double price, BufferedImage img)
{
this.id=id;
this.name= name;
this.price=price;
this.img=img;

label_id.setText(""+ this.id);
label_name.setText(""+ this.name);
label_price.setText(""+ this.price);

imagePanel.setImage(img);
}

public int id;
public String name;
public double price;
public BufferedImage img;

private JLabel label_price;
private JLabel label_name;
private JLabel label_id;
private ImagePanel imagePanel;
private JLabel lblUd;
private JLabel lblName;
private JLabel lblPricePerUnit;

}

import java.awt.EventQueue; 
import java.awt.image.BufferedImage;
import java.sql.*;

import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder; 


public class selectProduct extends JFrame
{

	private JPanel contentPane;

	public static void main(String[] args)
	{
		EventQueue.invokeLater(new Runnable()
		{
			public void run()
			{
				try
				{
					selectProduct frame = new selectProduct();
					frame.setVisible(true);
				} catch (Exception e)
				{
					e.printStackTrace();
				}
			}
		});
	}

	public selectProduct()
	{
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setBounds(100, 100, 450, 300);
		contentPane = new JPanel();
		contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
		setContentPane(contentPane);
		contentPane.setLayout(null);
		// //////////////////////////////////
		try
		{
			Connection con = null;
			Class.forName("com.mysql.jdbc.Driver");
			con = (Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/yyy", "root", "1234");
			Statement st = con.createStatement();
			ResultSet rs = st.executeQuery("SELECT * FROM product");
			Class.forName("com.mysql.jdbc.Driver");

			int i=0;
			while (rs.next())
			{
				ProductPanel pp = new ProductPanel();
				BufferedImage img = ImageIO.read(rs.getBinaryStream(4));
				pp.setParam(rs.getInt(1), rs.getString(2), rs.getDouble(3), img);
				pp.setBounds(0, i*120 + 20, 500, 120);
				this.contentPane.add(pp);
				
				System.out.println(pp.id +" "+ pp.name);
				i++;
			}

		} catch (Exception ee)
		{
			ee.printStackTrace();
		}

	}
}

ดึง RSS โดยใช้ JAVA

try
		{
			URL yahoo = new URL("http://rss.cnn.com/rss/edition.rss");
			BufferedReader in = new BufferedReader(new InputStreamReader(yahoo.openStream()));
			Scanner sc = new Scanner(in);

			while (sc.hasNext())
			{
				String s = sc.nextLine();
				System.out.println(s);
			}

			sc.close();

		} catch (MalformedURLException e)
		{
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e)
		{
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

เป็นการวาดรูปต้นไม้ binary search tree ครับ

import java.awt.Color;
import java.awt.Graphics;

public class TreeNode {
	public int data;
	public TreeNode left, right;

	public TreeNode() {
	}

	public TreeNode(int x) {
		data = x;
	}

	public void draw(Graphics g, int x, int y) {

		
		g.setColor(Color.pink);
		g.fillOval(x, y, 40, 40);
		g.setColor(Color.black);
		g.drawString("" + data, x + 15, y + 23);

	}
}

import java.awt.Graphics;

public class BSTree {
	public TreeNode root;

	public void add(int x) {
		if (root == null) {
			root = new TreeNode(x);
			return;
		}
		add(x, root);
	}

	public void add(int x, TreeNode n) {
		if (n == null)
			return;
		if (n.data == x)
			return;

		if (n.data < x) {
			if (n.right == null) {
				n.right = new TreeNode(x);
			} else {
				add(x, n.right);
			}
		} else {
			if (n.left == null) {
				n.left = new TreeNode(x);
			} else {
				add(x, n.left);
			}
		}
	}

	public int numNode(TreeNode n) {
		if (n == null)
			return 0;
		int k = 0;
		if (n.left != null) {
			k = k + numNode(n.left);
		}
		if (n.right != null) {
			k = k + numNode(n.right);
		}

		return k + 1;
	}

	public int height(TreeNode n) {
		if (n == null)
			return -1;
		if (n.left == null && n.right == null) {
			return 0;
		}
		int kl = 0;
		int kr = 0;

		if (n.left != null) {
			kl = height(n.left);
		}
		if (n.right != null) {
			kr = height(n.right);
		}

		return kl > kr ? kl + 1 : kr + 1;
	}

	int stepX;
	int stepY;

	public void draw(Graphics g, int width, int height) {

		int num = numNode(root);
		int h = height(root);

		stepX = width / (num + 1);
		stepY = height / (h + 1);

		draw(g, 1, num, 1, root,-1,-1);
	}

	public int draw(Graphics g, int start_x, int end_x, int height, TreeNode t,int x_mom ,int y_mom) {
		int num_l = numNode(t.left);

		int x_now=(num_l + start_x) * stepX;
		int y_now= height * stepY;
		
		
		
		t.draw(g, x_now, y_now);
		
		if (t.left != null) {
			draw(g, start_x, start_x + num_l - 1, height + 1, t.left,x_now, y_now);
		}
		if (t.right!= null) {
			draw(g, start_x + num_l + 1, end_x, height + 1, t.right,x_now, y_now);
		}
		
		if(x_mom != -1 && y_mom !=-1)
		{
			g.drawLine(x_mom+15, y_mom+15, x_now+15, y_now+15);
		}
		return 0;
	}

}

import java.awt.Graphics;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class GUI extends JPanel {
	BSTree t;
	public GUI() {
		  t = new BSTree();
		for (int i = 0; i < 100; i++) {
			int k=(int) (Math.random() * 100);
			t.add(k);
			System.out.println(k);
		}
		System.out.println(t.height(t.root));

		JFrame f = new JFrame();
		f.add(this);
		f.setSize(600, 600);
		f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		f.setVisible(true);

	}

	public void paint(Graphics g) {
		super.paint(g);
		if(t!=null){
			t.draw(g, this.getWidth(), this.getHeight());
		}
	}

	public static void main(String[] args) {

		new GUI();
	}

}

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