electroalbum.java

java的几个小程序

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

public class ElectroAlbum extends Applet {
	private Choice myChoice;

	private String[] myString1, myString2;

	private int totalPics;

	private Image offI;

	private Image[]  img;

	private Graphics offG;

	private MediaTracker imagetracker;

	public void init() {
		this.setLayout(null);
		myChoice = new Choice();
		myChoice.setBounds(10, 10, 290, 20);
		totalPics = Integer.parseInt(getParameter("TotalPic"));
		System.out.println(totalPics);
		myString1 = new String[totalPics];
		myString2 = new String[totalPics];
		img = new Image[totalPics];
		for (int i = 0; i < totalPics; i++) {
			myString1[i] = new String("");
			myString2[i] = new String("");
		}
		String s = new String("");
		imagetracker = new MediaTracker(this);
		for (int i = 0; i < totalPics; i++) {
			s = getParameter("Text" + (i + 1));
			myString1[i] = s;
			System.out.println(myString1[i]);
			myChoice.addItem(s);//向下拉列表中增加选项
			s = getParameter("Picture" + (i + 1));
			myString2[i] = s;
			img[i] = getImage(getDocumentBase(), s);
			imagetracker.addImage(img[i], 0);
			System.out.println(myString2[i]);
		}
		try {
			imagetracker.waitForID(0);
		} catch (InterruptedException e) {

		}
		add(myChoice);
		offI = createImage(getSize().width, getSize().height - 40);
		offG = offI.getGraphics();
		offI = img[0];
		offG.drawImage(offI, 0, 0, this);
		repaint();
	}

	public void paint(Graphics g) {
		g.drawImage(offI, 10, 40, this);
	}
//使用action()方法来获得Java Applet小程序运行时所发生的事件
	public boolean action(Event e, Object o) {
		if (e.target == myChoice) {
			//String s = new String("");
			offG.setColor(this.getBackground());
			offG.fillRect(0, 40, getSize().width, getSize().height - 40);
			offI = img[myChoice.getSelectedIndex()];
			offG.drawImage(offI, 0, 0, this);
			repaint();
		}
		return true;
	}
}