CodeBuilder.java

package message.utils;

import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.util.Random;

/**
 * 验证码生成器.
 *
 * @author sunhao(sunhao.java@gmail.com)
 * @version V1.0, 14-5-10 下午10:04
 */
public class CodeBuilder {
    /**
     * 验证码在session中默认的ID
     */
    public static final String VERITY_CODE_KEY = "verityCode";

    private CodeBuilder() {
    }

    /**
     * 生成验证码图片文件
     *
     * @param length  验证码数字长度
     * @param request
     * @param key     数字字符串放入session中的key
     * @return
     */
    public static BufferedImage buildCode(int length, HttpServletRequest request, String key) {
        length = (length <= 0 ? 4 : length);
        //内存中创建图像
        int width = length * 15, height = 20;
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

        //获取图像上下文
        Graphics graphics = image.getGraphics();

        //随机类
        Random random = new Random();

        //设置背景色
        graphics.setColor(getRandomColor(200, 250));
        graphics.fillRect(0, 0, width, height);

        //设置字体
        graphics.setFont(new Font("Times New Roman", Font.PLAIN, 18));

        //随机产生干扰线
        graphics.setColor(getRandomColor(160, 200));
        for (int i = 0; i < 155; i++) {
            int x = random.nextInt(width);
            int y = random.nextInt(height);
            int xl = random.nextInt(12);
            int yl = random.nextInt(12);
            graphics.drawLine(x, y, x + xl, y + yl);
        }

        // 取随机产生的认证码(4位数字)
        String sRand = "";
        for (int i = 0; i < length; i++) {
            String rand = String.valueOf(random.nextInt(10));
            sRand += rand;
            // 将认证码显示到图象中
            graphics.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));
            // 调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
            graphics.drawString(rand, 13 * i + 6, 16);
        }

        // 图象生效
        graphics.dispose();

        // 将认证码存入SESSION
        // 默认的session key
        if (request != null) {
            key = (StringUtils.isEmpty(key) ? VERITY_CODE_KEY : key);
            request.getSession().setAttribute(key, sRand);
        }

        return image;
    }

    private static Color getRandomColor(int fontColor, int backColor) {
        Random random = new Random();
        if (fontColor > 255)
            fontColor = 255;
        if (backColor > 255)
            backColor = 255;

        int red = fontColor + random.nextInt(backColor - fontColor);
        int green = fontColor + random.nextInt(backColor - fontColor);
        int blue = fontColor + random.nextInt(backColor - fontColor);

        return new Color(red, green, blue);
    }
}