我想做一个对话框,对话框里有菜单,其中"pain"菜单按下是可以花一条直线,但现在我不知道画线的函数咋写,事件响应咱设计,请各位帮忙!!

Question

package ygh;import java.awt.*;
import java.awt.event.*;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JMenuBar;
import javax.swing.JMenu;
import javax.swing.JMenuItem;
import javax.swing.JToolBar;
import javax.swing.JButton;
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import java.awt.BorderLayout;
import javax.swing.BorderFactory;
import java.awt.Rectangle;
import java.awt.Font;
import javax.swing.*;
import java.awt.Graphics;
import java.applet.Applet;/**
 * <p>Title: </p>
 *
 * <p>Description: </p>
 *
 * <p>Copyright: Copyright (c) 2006</p>
 *
 * <p>Company: </p>
 *
 * @author not attributable
 * @version 1.0
 */
public class helloworldFrame extends JFrame {
    JPanel contentPane;
    BorderLayout borderLayout1 = new BorderLayout();
    JMenuBar jMenuBar1 = new JMenuBar();
    JMenu jMenuFile = new JMenu();
    JMenuItem jMenuFileExit = new JMenuItem();
    JMenu jMenuHelp = new JMenu();
    JMenuItem jMenuHelpAbout = new JMenuItem();
    JToolBar jToolBar = new JToolBar();
    JButton jButton1 = new JButton();
    JButton jButton2 = new JButton();
    JButton jButton3 = new JButton();
    ImageIcon image1 = new ImageIcon(ygh.helloworldFrame.class.getResource(
            "openFile.png"));
    ImageIcon image2 = new ImageIcon(ygh.helloworldFrame.class.getResource(
            "closeFile.png"));
    ImageIcon image3 = new ImageIcon(ygh.helloworldFrame.class.getResource(
            "help.png"));
    JLabel statusBar = new JLabel();
    JPanel jPanel1 = new JPanel();
    JLabel jLabel1 = new JLabel();
    JMenu jMenu1 = new JMenu();
    JMenuItem jMenuItem1 = new JMenuItem();
    private int i=0;    public helloworldFrame() {
        try {
            setDefaultCloseOperation(EXIT_ON_CLOSE);
            jbInit();
        } catch (Exception exception) {
            exception.printStackTrace();
        }
    }
  
    private void jbInit() throws Exception {
        contentPane = (JPanel) getContentPane();
        contentPane.setLayout(borderLayout1);
        setSize(new Dimension(400, 300));
        setTitle("helloworld");
        statusBar.setText(" ");
        jMenuFile.setText("File");
        jMenuFileExit.setText("Exit");
        jMenuFileExit.addActionListener(new
                                        helloworldFrame_jMenuFileExit_ActionAdapter(this));
        jMenuHelp.setText("Help");
        jMenuHelpAbout.setText("About");
        jMenuHelpAbout.addActionListener(new
                                         helloworldFrame_jMenuHelpAbout_ActionAdapter(this));
        jPanel1.setBackground(Color.white);
        jPanel1.setBorder(BorderFactory.createEtchedBorder());
        jPanel1.setLayout(null);
        jLabel1.setFont(new java.awt.Font("Serif", Font.PLAIN, 28));
        jLabel1.setHorizontalAlignment(SwingConstants.CENTER);
        jLabel1.setText("hellow world!");
        jLabel1.setBounds(new Rectangle(132, 111, 218, 74));
        jMenuItem1.setText("pain");
        jMenuItem1.addActionListener(new
                                     helloworldFrame_jMenuItem1_actionAdapter(this));
        jMenuBar1.add(jMenuFile);
        jMenuFile.add(jMenuFileExit);
        jMenuFile.add(jMenuItem1);
        jMenuBar1.add(jMenuHelp);
        jMenuHelp.add(jMenuHelpAbout);
        setJMenuBar(jMenuBar1);
        jButton1.setIcon(image1);
        jButton1.setToolTipText("Open File");
        jButton2.setIcon(image2);
        jButton2.setToolTipText("Close File");
        jButton3.setIcon(image3);
        jButton3.setToolTipText("Help");
        jToolBar.add(jButton1);
        jToolBar.add(jButton2);
        jToolBar.add(jButton3);
        contentPane.add(jToolBar, BorderLayout.NORTH);
        contentPane.add(statusBar, BorderLayout.SOUTH);
        contentPane.add(jPanel1, java.awt.BorderLayout.CENTER);
        jPanel1.add(jLabel1);
    }    void jMenuFileExit_actionPerformed(ActionEvent actionEvent) {
        System.exit(0);
    }
    void jMenuHelpAbout_actionPerformed(ActionEvent actionEvent) {
        helloworldFrame_AboutBox dlg = new helloworldFrame_AboutBox(this);
        Dimension dlgSize = dlg.getPreferredSize();
        Dimension frmSize = getSize();
        Point loc = getLocation();
        dlg.setLocation((frmSize.width - dlgSize.width) / 2 + loc.x,
                        (frmSize.height - dlgSize.height) / 2 + loc.y);
        dlg.setModal(true);
        dlg.pack();
        dlg.setVisible(true);
    }    public void jMenuItem1_actionPerformed(ActionEvent e) {  
    }
}
class helloworldFrame_jMenuFileExit_ActionAdapter implements ActionListener {
    helloworldFrame adaptee;    helloworldFrame_jMenuFileExit_ActionAdapter(helloworldFrame adaptee) {
        this.adaptee = adaptee;
    }    public void actionPerformed(ActionEvent actionEvent) {
        adaptee.jMenuFileExit_actionPerformed(actionEvent);
    }
}
class helloworldFrame_jMenuItem1_actionAdapter implements ActionListener {
    private helloworldFrame adaptee;
    helloworldFrame_jMenuItem1_actionAdapter(helloworldFrame adaptee) {
        this.adaptee = adaptee;
    }    public void actionPerformed(ActionEvent e) {
        adaptee.jMenuItem1_actionPerformed(e);
    }
}
class helloworldFrame_jMenuHelpAbout_ActionAdapter implements ActionListener {
    helloworldFrame adaptee;    helloworldFrame_jMenuHelpAbout_ActionAdapter(helloworldFrame adaptee) {
        this.adaptee = adaptee;
    }    public void actionPerformed(ActionEvent actionEvent) {
        adaptee.jMenuHelpAbout_actionPerformed(actionEvent);
    }
}

Answer 1

java.awt.geom.Line2D
你可以用Line2D试试看
就是先new一个实例
然后修改它的属性好了

Answer 2

Graphics g
g.drawLine(...)方法也可以

Answer 3

谢谢moon_cool(月影剑) :我试了一下,那两个方法都不可以,我是想在事件响应后才画线,还有,画点的函数也可以,我是想用Bresenham算法把画直线画圆和画椭圆实现,一点菜单就可以画,Bresenham算法我已经有了......