1、Java画线
  1 import java.awt.Color;

 import java.awt.Container;

 import java.awt.Graphics;

 import java.awt.Point;

 import java.awt.event.ActionEvent;

 import java.awt.event.ActionListener;

 import javax.swing.JFrame;

 import javax.swing.JMenu;

 import javax.swing.JMenuBar;

 import javax.swing.JMenuItem;

 import javax.swing.JPanel;

 class MyPanel extends JPanel {

     public static final int MODE_LINE = 1;

     public static final int MODE_POINT = 2;

     //

     private int drawMode = MODE_POINT;

     @Override

     protected void paintComponent(Graphics g) {

         // super.paintComponent(g);

         // g.setColor(Color.red);

         // g.fillOval(10, 10, 100, 80);

         drawSinAdapteSize(g);

         g.dispose();

     }

     // 自适应的绘图方法

     private void drawSinAdapteSize(Graphics g) {

         g.setColor(Color.red);

         int w = getWidth();

         int h = getHeight();

         int SCALE_X = (int) (w / (2 * Math.PI));

         int SCALE_Y = h / 2 - 2;

         int OFFSET = h / 2;

         Point start = new Point(0, OFFSET);

         for (int x = 1; x <= SCALE_X * 2 * Math.PI; x++) {

             int y = OFFSET - (int) (SCALE_Y * Math.sin(x * 1.0 / SCALE_X));

             // 根据属性，决定画线还是画点

             if (drawMode == MODE_POINT) {

                 g.fillOval(x - 1, y - 1, 2, 2);

             } else if (drawMode == MODE_LINE) {

                 g.drawLine(start.x, start.y, x, y);

                 start.x = x;

                 start.y = y;

             }

         }

     }

     public void setDrawMode(int mode) {

         this.drawMode = mode;

     }

     // 绘制制定大小的曲线

     private void drawSin(Graphics g) {

         g.setColor(Color.red);

         // y = 220 - 200 * sin(x/100)

         for (int x = 0; x <= 100 * 2 * Math.PI; x++) {

             int y = 220 - (int) (200 * Math.sin(x / 100.0));

             g.fillOval(x - 1, y - 1, 2, 2);

         }

     }

 }

 public class DrawFrame extends JFrame implements ActionListener {

     // 属性

     MyPanel panel = null;

     // 方法

     public DrawFrame() {

         this.setTitle("绘图");

         setSize(650, 500);

         setDefaultCloseOperation(EXIT_ON_CLOSE);

         setLocationRelativeTo(null);

         panel = new MyPanel();

         panel.setBackground(Color.LIGHT_GRAY);

         Container cp = getContentPane();

         cp.add(panel);

         // JMenuBar

         JMenuBar menuBar = new JMenuBar();

         // JMenu

         JMenu menu = new JMenu("Draw");

         // JMenuItem

         JMenuItem item = new JMenuItem("Line");

         menu.add(item);

         item.addActionListener(this);

         item = new JMenuItem("Point");

         menu.add(item);

         item.addActionListener(this);

         menuBar.add(menu);

         this.setJMenuBar(menuBar);

     }

     public static void main(String[] args) {

         JFrame frame = new DrawFrame();

         frame.setVisible(true);

     }

     @Override

     public void actionPerformed(ActionEvent event) {

         String cmd = event.getActionCommand();

         if ("Line".equals(cmd)) {

             panel.setDrawMode(MyPanel.MODE_LINE);

         } else if ("Point".equals(cmd)) {

             panel.setDrawMode(MyPanel.MODE_POINT);

         }

         panel.repaint();

     }

 }

 import java.awt.event.ActionEvent;

 import java.awt.event.ActionListener;

 import javax.swing.JFrame;

 import javax.swing.JMenu;

 import javax.swing.JMenuBar;

 import javax.swing.JMenuItem;

 import javax.swing.JOptionPane;

 public class MenuFrame extends JFrame implements ActionListener {

     /**

      * JMuneBar(菜单栏)中包含多项Jmenu(菜单),Jmenu下有多项JMenuItem(菜单项)

      */

     public MenuFrame() {

         this.setTitle("MenuFrame");

         this.setSize(600, 400);

         setLocationRelativeTo(null);

         setDefaultCloseOperation(EXIT_ON_CLOSE);

         /**

          * 由于失误，将所有的组件都用awt下的Menu,MenuItem,MenuBar来实现了，导致菜单中的汉字为乱码

          */

         JMenuBar menuBar=new JMenuBar();

         JMenu menu=new JMenu("File");

         JMenuItem menuItem=new JMenuItem("新建");

         JMenuItem exit=new JMenuItem("退出");

         exit.addActionListener(this);

         JMenuItem about=new JMenuItem("关于...");

         about.addActionListener(this);

         menu.add(menuItem);

         menu.add(exit);

         menu.add(about);

         menuBar.add(menu);

         menuBar.add(new JMenu("Edit"));

         this.setJMenuBar(menuBar);//注意最后要将菜单栏加到MenuFrame组件中去，不然菜单不可见

     }

     public static void main(String[] args) {

         JFrame frame=new MenuFrame();

         frame.setVisible(true);

     }

     @Override

     public void actionPerformed(ActionEvent e) {

         String cmd=e.getActionCommand();

         if(cmd.equals("Exit")) {

             dispose();

         }else if(cmd.equals("About")) {

             JOptionPane.showMessageDialog(null, "菜单演示系统");

         }

     }

 }