applet1.java

矩阵乘法的计算程序

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

/**
 * This class reads PARAM tags from its HTML host page and sets
 * the color and label properties of the applet. Program execution
 * begins with the init() method. 
 */
public class Applet1 extends Applet
{
	String fontList[];
	
	public void init()
	{
		initForm();

		usePageParams();
		//getToolkit()为Applet类的方法 获得Applet的Toolkit对象
		//getFontList()为Toolkit对象的方法 获得Toolkit对象的字体名称列表(英文)
		fontList=getToolkit().getFontList();

		// TODO: Add any constructor code after initForm call.
	}
	
	public void paint (Graphics g){
		//Dimension为一个尺寸类由高宽两个数据成员组成
		//getSize()为Applet为类的一个方法获得当前Applet对象的尺寸
		Dimension d=this.getSize();
		int i;
		//根据Applet对象的位置确定显示字体名称的位置
		int x=d.width/3,y=d.height /fontList.length-5;
		for ( i=0;i<fontList.length;i++){
			Font f; //定义一个字体对象句柄
			//字体对象实体由字体名 字体格式 字体大小三部分组成
			f=new Font(fontList[i],Font.BOLD,18);
			//设置当前使用的字体
			g.setFont(f);
			g.drawString(fontList[i],5,y*(i+1));
			f=new Font(fontList[i],Font.ITALIC ,18);
			g.setFont(f);
			g.drawString(fontList[i],x,y*(i+1));
			f=new Font(fontList[i],Font.PLAIN ,18);
			g.setFont(f);
			g.drawString(fontList[i],x+x,y*(i+1));
			
		}
		Font f;
		f=new Font("黑体",Font.BOLD,28);
		g.setFont(f);
		g.drawString("黑体字体示例",5,y*(i+1));
		
	}
	private	final String labelParam = "label";
	private	final String backgroundParam = "background";
	private	final String foregroundParam = "foreground";

	/**
	 * Reads parameters from the applet's HTML host and sets applet
	 * properties.
	 */
	private void usePageParams()
	{
		final String defaultLabel = "Default label";
		final String defaultBackground = "C0C0C0";
		final String defaultForeground = "000000";
		String labelValue;
		String backgroundValue;
		String foregroundValue;

		/** 
		 * Read the <PARAM NAME="label" VALUE="some string">,
		 * <PARAM NAME="background" VALUE="rrggbb">,
		 * and <PARAM NAME="foreground" VALUE="rrggbb"> tags from
		 * the applet's HTML host.
		 */
		labelValue = getParameter(labelParam);
		backgroundValue = getParameter(backgroundParam);
		foregroundValue = getParameter(foregroundParam);

		if ((labelValue == null) || (backgroundValue == null) ||
			(foregroundValue == null))
		{
			/**
			 * There was something wrong with the HTML host tags.
			 * Generate default values.
			 */
			labelValue = defaultLabel;
			backgroundValue = defaultBackground;
			foregroundValue = defaultForeground;
		}

		/**
		 * Set the applet's string label, background color, and
		 * foreground colors.
		 */
		label1.setText(labelValue);
		label1.setBackground(stringToColor(backgroundValue));
		label1.setForeground(stringToColor(foregroundValue));
		this.setBackground(stringToColor(backgroundValue));
		this.setForeground(stringToColor(foregroundValue));
	}

	/**
	 * Converts a string formatted as "rrggbb" to an awt.Color object
	 */
	private Color stringToColor(String paramValue)
	{
		int red;
		int green;
		int blue;

		red = (Integer.decode("0x" + paramValue.substring(0,2))).intValue();
		green = (Integer.decode("0x" + paramValue.substring(2,4))).intValue();
		blue = (Integer.decode("0x" + paramValue.substring(4,6))).intValue();

		return new Color(red,green,blue);
	}

	/**
	 * External interface used by design tools to show properties of an applet.
	 */
	public String[][] getParameterInfo()
	{
		String[][] info =
		{
			{ labelParam, "String", "Label string to be displayed" },
			{ backgroundParam, "String", "Background color, format \"rrggbb\"" },
			{ foregroundParam, "String", "Foreground color, format \"rrggbb\"" },
		};
		return info;
	}

	Label label1 = new Label();

	/**
	 * Intializes values for the applet and its components
	 */
	void initForm()
	{
		this.setBackground(Color.lightGray);
		this.setForeground(Color.black);
		label1.setText("label1");
		this.setLayout(new BorderLayout());
		this.add("North",label1);
	}
}