ch7_e7_8.java

代码包括《Java语言与面向对象程序设计题解与实验指导》一书中 “习题解答”部分的所有程序的Java源代码和编译后生成的字节码或相应的HTML文件。 盘中的目录与书中的章节一致。

import java.applet.Applet; 
import java.awt.*;
import java.awt.event.*;

public class ch7_e7_8 extends Applet implements ActionListener
{
    Image[] m_Images;
    int totalImages = 18;
    int currentImage = 0;
    int frameChange = 0;
    
    Button leftRotateBtn = new Button("左旋");
    Button rightRotateBtn = new Button("右旋");

    public void init()
    {
        m_Images = new Image[totalImages];
        for(int i=0;i<totalImages;i++)
            m_Images[i] = getImage(getDocumentBase(),
                "images\\Img00" + (i+1) + ".gif");
        
        add(leftRotateBtn);
        add(rightRotateBtn);
        leftRotateBtn.addActionListener(this);
        rightRotateBtn.addActionListener(this);
    }
    public void start()
    {
        currentImage = 0;
    }
    public void paint(Graphics g)
    {
        g.drawImage(m_Images[currentImage],50,50,this);
        currentImage = currentImage+frameChange;
        if(currentImage < 0)
            currentImage += totalImages;
        else
            currentImage %= totalImages;
        try{
            Thread.sleep(50);
        }
        catch(InterruptedException e)
        {
            showStatus(e.toString());
        }
        repaint();
    }
    public void actionPerformed(ActionEvent ae)
    {
        if(ae.getSource() == leftRotateBtn)
            frameChange = -1;
        else if(ae.getSource() == rightRotateBtn)
            frameChange = 1;
    }
}