lineshow.java

Java 范例实战 光盘使用说明 ========================== 本光盘的文件结构如下所示： =====================================

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

public class lineshow extends Applet implements Runnable {
    int yStep = 0, 
        xPos = 0, 
        yPos = 0, 
        textWidth = 0;
    Thread killme = null;
    String inputText = null;
    Font font = null;
    Color bgColor = null, 
          txtColor = null;

    public lineshow()
    {
        font = new Font("Helvetica", 2, 15);
        bgColor = new Color(255, 255, 255);
        txtColor = new Color(255, 0, 0);
        yPos = 15;
        yStep = 1;
    }

    public void init()
    {
        setBackground(bgColor);
        inputText = getParameter("text");

        if(inputText == null)
            inputText = "Hello! World!";

        FontMetrics fontmetrics = getFontMetrics(font);
        textWidth = fontmetrics.stringWidth(inputText);
    }

    public void start()
    {

        if(killme == null)
        {
            killme = new Thread(this);
            killme.start();
        }

    }

    public void stop()
    {
        killme = null;
    }

    public void setcoord()
    {
        xPos = xPos + 2;
        yPos = yPos + yStep;

        if(xPos > 500)
            xPos = -textWidth;

        if(yPos > 45)
            yStep = -1;

        if(yPos < 15)
            yStep = 1;

    }

    public void run()
    {

        while(killme != null) 
        {

            try
            {
                Thread.sleep(100L);
            }
            catch(InterruptedException _ex) { }

            setcoord();
            repaint();
        }

    }

    public void paint(Graphics g)
    {
        g.setColor(txtColor);
        g.setFont(font);
        g.drawString(inputText, xPos, yPos);
    }

}