生成驗證碼的java類

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;

//驗證碼
public final class ImageUtil {
    private static final String[] chars = { "0", "1", "2", "3", "4", "5", "6",
            "7", "8", "9", "A", "B", "C", "D", "E", "F", "G", "H", "J", "K",
            "L", "M", "N", "P" };
    private static final int SIZE = 5;// 字符長度
    private static final int LINES = 7;// 干擾線
    private static final int WIDTH = 100;
    private static final int HEIGHT = 50;
    private static final int FONT_SIZE = 30;// 字體大小

public static Map<String, BufferedImage> createImage() {
    StringBuffer sb = new StringBuffer();
    BufferedImage image = new BufferedImage(WIDTH, HEIGHT,
            BufferedImage.TYPE_INT_RGB);
    Graphics graphic = image.getGraphics();
    graphic.setColor(Color.LIGHT_GRAY);
    graphic.fillRect(0, 0, WIDTH, HEIGHT);
    Random ran = new Random();
    // 畫隨機字符
    for (int i = 1; i <= SIZE; i++) {

        int r = ran.nextInt(chars.length);
        graphic.setColor(getRandomColor());
        graphic.setFont(new Font(null, Font.BOLD + Font.ITALIC, FONT_SIZE));
        graphic.drawString(chars[r], (i - 1) * WIDTH / SIZE, HEIGHT / 2);
        sb.append(chars[r]);// 將字符保存，存入Session
    }
    // 畫干擾線
    for (int i = 1; i <= LINES; i++) {
        graphic.setColor(getRandomColor());
        graphic.drawLine(ran.nextInt(WIDTH), ran.nextInt(HEIGHT),
                ran.nextInt(WIDTH), ran.nextInt(HEIGHT));
    }
    Map<String, BufferedImage> map = new HashMap<String, BufferedImage>();
    map.put(sb.toString(), image);
    return map;
}

public static Color getRandomColor() {
    Random ran = new Random();
    Color color = new Color(ran.nextInt(156), ran.nextInt(156),
            ran.nextInt(156));
    return color;
}

}</pre>