Captcha.java

/*
 * Copyright 2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.noday.core.utils;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.imageio.stream.ImageInputStream;

import org.apache.shiro.session.Session;

import org.apache.commons.lang.RandomStringUtils;
import org.apache.commons.lang3.StringUtils;

/**
 * cat Captcha
 *
 * @author <a href="http://www.noday.net">Noday</a>
 * @version , 2012-11-24
 * @since 
 */
public class Captcha {

	private static final Random random = new Random();
	public static final String CAPTCHAKEY = "_key_of_captch";
	
	public static boolean validate(Session s, String captcha) {
		String text = (String) s.getAttribute(CAPTCHAKEY);
		return StringUtils.equalsIgnoreCase(text, captcha);
	}
	
	public static ByteArrayInputStream captchInputStream(Session s, int width, int height) throws IOException {
		String text = randText();
		s.setAttribute(CAPTCHAKEY, text);
		ByteArrayOutputStream out = new ByteArrayOutputStream();
		ImageIO.write(gen(text, width, height), "png", out);
		return new ByteArrayInputStream(out.toByteArray());
	}
	
	public static ImageInputStream captcha(Session s, int width, int height) throws IOException {
		String text = randText();
		s.setAttribute(CAPTCHAKEY, text);
		BufferedImage bi = gen(text, width, height);
		return ImageIO.createImageInputStream(bi);
	}
	public static BufferedImage gen(String text, int width, int height) throws IOException {
		BufferedImage bi = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
		Graphics2D g = (Graphics2D) bi.getGraphics();
		g.setColor(Color.GRAY);
		g.fillRect(0, 0, width, height);
		for (int i = 0; i < 10; i++) {
			g.setColor(randColor(150, 250));
			g.drawOval(random.nextInt(110), random.nextInt(24), 5+random.nextInt(10), 5+random.nextInt(10));
			Font f = new Font("Arial", Font.ITALIC, 20);
			g.setFont(f);
			g.setColor(randColor(10, 240));
			g.drawString(text, 4, 24);
		}
		return bi;
	}
	
	private static Color randColor(int fc, int bc) {
		if (fc > 255)
			fc = 255;
		if (bc > 255)
			bc = 255;
		int r = fc + random.nextInt(bc - fc);
		int g = fc + random.nextInt(bc - fc);
		int b = fc + random.nextInt(bc - fc);
		return new Color(r, g, b);
	}
	
	private static String randText() {
		String text = RandomStringUtils.randomAlphanumeric(4)
			.toUpperCase()
			.replace('0', 'A').replace('O', 'E')
			.replace('1', 'V').replace('I', 'R');
		return text;
	}
	
}