web登陆验证码验证

package util;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;
import javax.imageio.ImageIO;

public final class ImageUtil {

// 验证码字符集
private static final char[] chars = { 
	'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 
	'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 
	'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'};
// 字符数量
private static final int SIZE = 4;
// 干扰线数量
private static final int LINES = 5;
// 宽度
private static final int WIDTH = 80;
// 高度
private static final int HEIGHT = 40;
// 字体大小
private static final int FONT_SIZE = 30;

/**
 * 生成随机验证码及图片
 */
public static Object[] createImage() {
	StringBuffer sb = new StringBuffer();
	// 1.创建空白图片
	BufferedImage image = new BufferedImage(
		WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
	// 2.获取图片画笔
	Graphics graphic = image.getGraphics();
	// 3.设置画笔颜色
	graphic.setColor(Color.LIGHT_GRAY);
	// 4.绘制矩形背景
	graphic.fillRect(0, 0, WIDTH, HEIGHT);
	// 5.画随机字符
	Random ran = new Random();
	for (int i = 0; i <SIZE; i++) {
		// 取随机字符索引
		int n = ran.nextInt(chars.length);
		// 设置随机颜色
		graphic.setColor(getRandomColor());
		// 设置字体大小
		graphic.setFont(new Font(
			null, Font.BOLD + Font.ITALIC, FONT_SIZE));
		// 画字符
		graphic.drawString(
			chars[n] + "", i * WIDTH / SIZE, HEIGHT / 2);
		// 记录字符
		sb.append(chars[n]);
	}
	// 6.画干扰线
	for (int i = 0; i < LINES; i++) {
		// 设置随机颜色
		graphic.setColor(getRandomColor());
		// 随机画线
		graphic.drawLine(ran.nextInt(WIDTH), ran.nextInt(HEIGHT),
				ran.nextInt(WIDTH), ran.nextInt(HEIGHT));
	}
	// 7.返回验证码和图片
	return new Object[]{sb.toString(), image};
}

/**
 * 随机取色
 */
public static Color getRandomColor() {
	Random ran = new Random();
	Color color = new Color(ran.nextInt(256), 
			ran.nextInt(256), ran.nextInt(256));
	return color;
}

public static void main(String[] args) throws IOException {
	Object[] objs = createImage();
	System.out.println(objs[0]);
	BufferedImage image = (BufferedImage) objs[1];
	OutputStream os = new FileOutputStream("d:/1.jpg");
	ImageIO.write(image, "jpeg", os);
	os.close();
}

}