Java学习day086 部署Java程序（三）（applet：一个简单的applet、applet HTML标记属性、使用参数向applet传递信息）

/**
 *@author  zzehao
 */
import java.swt.*;
import javax.swing.*;

public class NotHelloWorld extends JApplet
{
	public void init()
	{
		EventQueue.invokeLater(() -> {
			JLabel label = new JLabel("Not a Hello,World applet",SwingConstants.CENTER);
			add(label);
		});
	}
}

<applet dass="applet/NotHel1olilorld.class" archive="NotHel1oWorld.jar" width="300",height="300">
</applet>

<applet dass="applet/NotHel1olilorld.class" archive="NotHel1oWorld.jar" width="300",height="300">
</applet>

〈applet code="FontParamApplet.class" ...>
<param name="font" value="Helvetica"/>
</applet>

public class FontParamApplet extends JApplet
{
    public void init()
    {
        String fontName = getParameter("font");
        ...
    }
    ...
}

int fontsize;
String sizeString= getParameter("size");
if (sizeString = null) fontSize = 12;
else fontSize = Integer.parseint(sizeString);

/**
 *@author  zzehao
 */
import java.awt.*;
import java.awt.font.*;
import java.awt.geom.*;
import javax.swing.*;

public class Chart extends JApplet
{
	public void init()
	{
		EventQueue.invokeLater(() -> {
			String v = getParameter("values");
			if (v == null) 
				return;
			int n = Integer.parseInt(v);
			double[] values = new double[n];
			String[] names = new String[n];
			for (int i = 0;i<n;i++)
			{
				values[i] = Double.parseDouble(getParameter("value."+(i+1)));
				name[i] = getParameter("name." + (i+1));
			}

			add(new ChartComponent(values,names,getParameter("title")));
		});
	}
}

//A component that draws a bar chart.
class ChartComponent extends JComponent
{ 
	private double[] values;
	private String[] names; 
	private String title;

	public ChartComponent(double[] v, String[] n, String t) 
	{
		values = v;
		names = n;
		title = t;
	}

	public void paintComponent(Graphics g)
	{ 
		Graphics2D g2 =(Graphics2D) g; 
		//compute the minimum and maximum values
		if (values == null) 
			return;
		double minValue = 0;
		double maxValue = 0;
		for (double v : values)
		{ 
			if (minValue>v) minValue = v;
			if (maxValue< v) maxValue = v;
		} 
		if (maxValue == minValue) 
			return;
		
		int panelWidth = getWidth();
		int panelHeight = getHeight();

		Font titleFont = new Font("SansSerif", Font.BOLD, 20);
		Font labelFont = new Font("SansSerif", Font.PLAIN, 10);

		//compute the extent of the title
		FontRenderContext context = g2.getFontRenderContext();
		Rectangle2D titleBounds = titleFont.getStringBounds(title, context);
		double titleWidth = titleBounds.getWidth();
		double top = titleBounds.getHeight();

		//draw the title
		double y= -titleBounds.getY(); //ascent
		double x = (panelWidth - titleWidth)/2;
		g2.setFont(titleFont);
		g2.drawString(title, (float)x, (float) y);

		//compute the extent of the bar labels
		LineMetrics labelMetrics = labelFont.getLineMetrics("", context);
		double bottom = labelMetrics.getHeight();

		y = panelHeight - labelMetrics.getDescent();
		g2.setFont(labelFont);

		//get the scale factor and width for the bars
		double scale =(panelHeight - top - bottom)/(maxValue - minValue);
		int barWidth =panelWidth /values.length;

		//draw the bars
		for (inti =0;i < values.length;i++)
		{
			//get the coordinates of the bar rectangle
			double x1 = i * barWidth + 1;
			double y1 = top;
			double height = values[i] * scale;
			if (values[i]>= 0)
				y1 += (maxValue - values[i])*scale;
			else
			{
				y1 += maxValue*scale;
				height = -height;
			}

			//fill the bar and draw the bar outline
			Rectangle2D rect = new Rectangle2D.Double(x1, y1, barWidth - 2, height);
			g2.setPaint(Color.RED);
			g2.fi11(rect);
			g2.setPaint(Color.BLACK);
			g2.draw(rect);

			//draw the centered label below the bar
			Rectangle2D labelBounds = labelFont.getStringBounds(names[i], context);

			double labelWidth = labelBounds.getWidth();
			x = x1 + (barWidth - labelWidth)/2;
			g2.drawString(names[i], (float) x, (float) y);
		}
	}
}