validcode.java

创建网页页面验证的验证码

package mawen.util;

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

public class ValidCode {
	/*
	 * px2pt:像素（px）转换为磅（pt）的系数，Windows缺省为0.75；MAC缺省为1 validString:验证字符串
	 */
	private double px2pt;

	private String fontName;

	private String validString;

	private int fontSize;

	private int margin;

	private int padding;

	private int length;

	private int offset;

	private int interference;

	private int foreground_low;

	private int foreground_high;

	private int background_low;

	private int background_high;

	final static private char[] CHARSET = { '0', '1', '2', '3', '4', '5', '6',
			'7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K',
			'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };

	final static private int CHARSET_SIZE = CHARSET.length;

	public ValidCode() {
		reset();
	}

	/*
	 * 生成随机数字字符串
	 */
	public static String getRandomID(int length) {
		StringBuffer sb = new StringBuffer();
		Random random = new Random();
		for (int i = 0; i < length; i++) {
			sb.append(CHARSET[random.nextInt(CHARSET_SIZE)]);
		}
		return sb.toString();
	}

	public String getRandomID() {
		return getRandomID(this.length);
	}

	/*
	 * 生成(绘画)验证码图像
	 */
	public BufferedImage getImage(final String str) {
		int length = str.length();
		int width = this.getWidth(length);
		int height = this.getHeight();

		BufferedImage image = new BufferedImage(width, height,
				BufferedImage.TYPE_INT_RGB);
		Graphics g = image.getGraphics(); // 获取图形上下文
		g.setColor(getBackgroundColor()); // 设定背景色
		g.fillRect(0, 0, width, height);
		g.setFont(new Font(this.fontName, Font.BOLD, this.fontSize)); // 设定字体

		lineInterfere(g, width, height); // 加上干扰纹
		for (int i = 0; i < length; i++) { // 绘画认证码
			g.setColor(getForegroundColor());
			g.drawString(str.substring(i, i + 1), (int) (this.margin + i
					* (this.padding + this.fontSize / this.px2pt)), height
					- this.margin);
		}

		lineInterfere(g, width, height); // 加上干扰纹
		g.dispose(); // 图象生效
		return image;
	}

	public BufferedImage getImage() {
		if ((this.validString == null) || this.validString.equalsIgnoreCase(""))
			this.validString = getRandomID(this.length);
		return getImage(this.validString);
	}

	/*
	 * 生成随机前景颜色
	 */
	private Color getForegroundColor() {
		return getRandomColor(foreground_low, foreground_high);
	}

	/*
	 * 生成随机背景颜色
	 */
	private Color getBackgroundColor() {
		return getRandomColor(background_low, background_high);
	}

	/*
	 * 生成随机的RGB颜色
	 */
	protected static Color getRandomColor(int low, int high) {
		low = (low < 0) ? 0 : low;
		low = (low > 255) ? 255 : low;
		high = (high < low) ? low : high;
		high = (high > 255) ? 255 : high;

		Random random = new Random();
		int r = low + random.nextInt(high - low);
		int g = low + random.nextInt(high - low);
		int b = low + random.nextInt(high - low);
		return new Color(r, g, b);
	}

	/*
	 * 随机产生多条干扰线，使图象中的认证码不易被其它程序探测到
	 */
	private void lineInterfere(Graphics g, int width, int height) {
		Random random = new Random();
		for (int i = 0; i < interference; i++) {
			int x = random.nextInt(width);
			int y = random.nextInt(height);
			int xl = random.nextInt(width);
			int yl = random.nextInt(height);
			g.setColor(getBackgroundColor());
			g.drawLine(x, y, x + xl, y + yl);
		}
	}

	/*
	 * 重新设置类参数为缺省值
	 */
	public void reset() {
		this.px2pt = 1.2;
		this.fontName = "Arial";
		this.fontSize = 14;
		this.margin = 4;
		this.padding = 0;
		this.offset = 0;
		this.foreground_low = 0;
		this.foreground_high = 112;
		this.background_low = 204;
		this.background_high = 256;
		this.interference = 7;
		this.length = 4;
	}

	public int getBackground_high() {
		return background_high;
	}

	public void setBackground_high(int background_high) {
		this.background_high = background_high;
	}

	public String getFontName() {
		return fontName;
	}

	public void setFontName(String fontName) {
		this.fontName = fontName;
	}

	public int getFontSize() {
		return fontSize;
	}

	public void setFontSize(int fontSize) {
		this.fontSize = fontSize;
	}

	public int getLength() {
		return length;
	}

	public void setLength(int length) {
		this.length = length;
	}

	public int getMargin() {
		return margin;
	}

	public void setMargin(int margin) {
		this.margin = margin;
	}

	public int getHeight() {
		return (int) (2 * this.margin + this.fontSize / this.px2pt);
	}

	public int getWidth() {
		return this.getWidth(this.length);
	}

	protected int getWidth(int lenght) {
		return (int) (this.offset + 2 * this.margin + length
				* (this.padding + this.fontSize / this.px2pt));
	}

	public void setBackground_low(int background_low) {
		this.background_low = background_low;
	}

	public void setForeground_high(int foreground_high) {
		this.foreground_high = foreground_high;
	}

	public void setForeground_low(int foreground_low) {
		this.foreground_low = foreground_low;
	}

	public void setInterference(int interference) {
		this.interference = interference;
	}

	public int getPadding() {
		return padding;
	}

	public void setPadding(int padding) {
		this.padding = padding;
	}

	public String getValidString() {
		return validString;
	}

	public void setValidString(String validString) {
		this.validString = validString.trim();
		this.length = this.validString.length();
	}

	public int getOffset() {
		return offset;
	}

	public void setOffset(int offset) {
		this.offset = offset;
	}

	public double getPx2pt() {
		return this.px2pt;
	}

	public void setPx2pt(double px2pt) {
		this.px2pt = px2pt;
	}

}