Java Applet Web图表实例:带徽标的垂直柱状图

这是这个Applet的html文件:








下面的画垂直柱状图的源码:

// Fig. 3.02_01: LogoVBar.java
// Java Applet Web图表实例3：带Java徽标的Web图表

import java.awt.*; // 引入 java.awt包中所有的类
import javax.swing.*; // 引入 javax.swing包中所有的类
public class LogoVBar extends JApplet
{
  Image logoJPG;
  Image offImage;
  Graphics offGraphics;
  int appletWidth = 600, appletHeight = 500;
  int bookSales[] = new int[5];
  String bookTitle[] =
  {
    "Python", "JAVA", "C#", "Perl", "PHP"
  };
  // 初始化颜色数组
  Color color[] =
  {
    new Color(99, 99, 0), Color.GREEN, Color.YELLOW, Color.RED, Color.BLUE
  };
  // 初始化绘图缓冲区
  public void init()
  {
    offImage = createImage(appletWidth, appletHeight);
    offGraphics = offImage.getGraphics();
    for (int i = 0; i < bookSales.length; i++)
    {
      bookSales[i] = 1+(int)(Math.random() * 100);
    }
    logoJPG = getImage(getDocumentBase(), "javaLogo.jpg");
  }
  public void paint(Graphics g)
  {
    // 调用父类的 paint 方法
    super.paint(g);
    update(g);
  } // paint 方法结束
  public void update(Graphics g)
  {
    // 绘制标题区域
    offGraphics.drawImage(logoJPG, 100, 0, this);
    offGraphics.setColor(Color.BLACK);
    offGraphics.setFont(new Font("方正粗宋简体", Font.BOLD, 30));
    offGraphics.drawString("带Java徽标的Web图表", 135, 40);
    // 绘制代表销售量的10条直线
    offGraphics.setFont(new Font("SansSerif", Font.PLAIN, 12));
    int salesValue = 0;
    for (int i = 418; i > 0; i -= 38)
    {
      offGraphics.setColor(Color.BLACK);
      offGraphics.drawString("" + salesValue, 40, (i + 27));
      offGraphics.setColor(Color.LIGHT_GRAY);
      offGraphics.drawLine(80, (i + 27), 520, (i + 27));
      salesValue += 10;
    }
    // 绘制实心矩形
    int drawHigh = 0;
    for (int i = 0; i < bookTitle.length; i++)
    {
      offGraphics.setColor(color[i]);
      drawHigh = (int)(Math.ceil(bookSales[i] * 3.8));
      offGraphics.fill3DRect(110+i * 80, 445-drawHigh, 50, drawHigh, true);
      offGraphics.setColor(Color.BLACK);
      offGraphics.drawString(bookTitle[i], 110+i * 80, 465);
    }
    // 绘制坐标系
    offGraphics.setColor(Color.BLACK);
    offGraphics.drawLine(80, 40, 80, 445);
    offGraphics.drawLine(80, 445, 550, 445);
    // 绘制坐标系说明
    offGraphics.setFont(new Font("黑体", Font.BOLD, 16));
    offGraphics.drawString("销售量", 20, 50);
    offGraphics.drawString("编程书籍", 500, 465);
    // 输出缓冲区图像
    g.drawImage(offImage, 0, 0, null);
  }
}

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