Create captcha Image for Servlet

Description

Demo Code


import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Main{
    public static final String CAPTCHA = "CAPTCHA";
    private static final Random random = new Random();
    //from www  .  j a v  a  2 s  .  com
    public static boolean captcha(int width, int height, int size,
            CAPTCHA_TYPE captchaType, HttpServletRequest request,
            HttpServletResponse response) {
        String code = getCode(size, captchaType);
        BufferedImage bi = getBufferedImage(width, height, size,
                captchaType, code);

        request.getSession().setAttribute(CAPTCHA, code);
        ServletOutputStream sos = null;
        try {
            response.addIntHeader("Expires", 0);
            response.addHeader("Cache-Control", "no-cache");
            response.addHeader("Pragma", "no-cache");
            response.setContentType("image/jpeg");
            sos = response.getOutputStream();
            boolean result = ImageIO.write(bi, "jpg", sos);
            sos.flush();
            sos.close();
            sos = null;
            return result;
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (sos != null)
                    sos.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return false;
    }
    
    public static boolean captcha(int width, int height, int size,
            CAPTCHA_TYPE captchaType, String fileName) {
        String code = getCode(size, captchaType);
        BufferedImage bi = getBufferedImage(width, height, size,
                captchaType, code);

        try {
            return ImageIO.write(bi, "jpg", new File(fileName));
        } catch (IOException e) {
            e.printStackTrace();
        }
        return false;
    }
    public static String getCode(int size, CAPTCHA_TYPE captchaType) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < size; i++) {
            switch (captchaType) {
            case ENGLISH:
                sb.append(getEnglish());
                break;
            case NUMBER:
                sb.append(getNumber());
                break;
            case CHINESE:
                sb.append(getChinese());
                break;
            case ENGLISH_NUMBER:
                if (random.nextInt(i % 2 + 1) == 1) {
                    sb.append(getNumber());
                } else {
                    sb.append(getEnglish());
                }
                break;
            case ALL:
                int j = random.nextInt(i * (i + 3) / 2 + 1);
                if (j == 1) {
                    sb.append(getNumber());
                } else if (j == 2) {
                    sb.append(getChinese());
                } else {
                    sb.append(getEnglish());
                }
                break;
            }
        }
        return sb.toString();
    }
    public static BufferedImage getBufferedImage(int width, int height,
            int size, CAPTCHA_TYPE captchaType, String code) {
        BufferedImage bi = new BufferedImage(width, height,
                BufferedImage.TYPE_INT_RGB);
        Graphics2D g2d = bi.createGraphics();

        // 
        g2d.setColor(Color.WHITE);
        g2d.fillRect(0, 0, width, height);

        // 
        g2d.setColor(Color.BLACK);
        g2d.drawRect(0, 0, width - 1, height - 1);

        // 
        for (int i = 0; i < 100; i++) {
            g2d.setColor(getColor(180, 230));
            int x = random.nextInt(width);
            int y = random.nextInt(height);
            int w = random.nextInt(4);
            int d = random.nextInt(4);

            g2d.fillOval(x, y, w, d);
        }

        // 
        int fontSize = Math.min(width / size, height);
        g2d.setFont(new Font("", Font.BOLD, fontSize));
        char[] chars = code.toCharArray();
        for (int i = 0; i < size; i++) {
            g2d.setColor(getColor(60, 150));
            // 
            AffineTransform affine = new AffineTransform();
            affine.setToRotation(Math.PI / 4 * random.nextDouble()
                    * (random.nextBoolean()  1 : -1), (width / size) * i
                    + fontSize / 2, height / 2);
            g2d.setTransform(affine);
            g2d.drawChars(chars, i, 1, (width / size) * i, height / 2
                    + fontSize / 2);
        }
        g2d.dispose();
        return bi;
    }
    private static String getEnglish() {
        int temp = random.nextInt(26) + 65;
        return String.valueOf((char) temp);
    }
    private static String getNumber() {
        int temp = random.nextInt(10) + 48;
        return String.valueOf((char) temp);
    }
    private static String getChinese() {
        // 
        String temp = "";
        String[] rBase = { "0", "1", "2", "3", "4", "5", "6", "7", "8",
                "9", "a", "b", "c", "d", "e", "f" };
        // 1
        int r1 = random.nextInt(3) + 11; // 1114
        String str_r1 = rBase[r1];
        // 2
        int r2;
        if (r1 == 13) {
            r2 = random.nextInt(7); // 07
        } else {
            r2 = random.nextInt(16); // 016
        }
        String str_r2 = rBase[r2];

        // 1
        int r3 = random.nextInt(6) + 10; // 1016
        String str_r3 = rBase[r3];
        // 2
        int r4;
        if (r3 == 10) {
            r4 = random.nextInt(15) + 1; // 116
        } else if (r3 == 15) {
            r4 = random.nextInt(15); // 015
        } else {
            r4 = random.nextInt(16); // 016
        }
        String str_r4 = rBase[r4];

        // 
        byte[] bytes = new byte[2];
        // 1
        String str_r12 = str_r1 + str_r2;
        int tempLow = Integer.parseInt(str_r12, 16);
        bytes[0] = (byte) tempLow;
        // 2
        String str_r34 = str_r3 + str_r4;
        int tempHigh = Integer.parseInt(str_r34, 16);
        bytes[1] = (byte) tempHigh;
        try {
            // 
            temp = new String(bytes, "GB2312");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        return temp;
    }
    private static Color getColor(int fc, int bc) {
        int r = 0, g = 0, b = 0;
        if (fc > 255)
            fc = 255;
        if (bc > 255)
            bc = 255;
        if (fc == 255 && bc == fc) {
            r = random.nextInt(255);
            g = random.nextInt(255);
            b = random.nextInt(255);
        } else {
            r = fc + random.nextInt(bc - fc);
            g = fc + random.nextInt(bc - fc);
            b = fc + random.nextInt(bc - fc);
        }
        return new Color(r, g, b);
    }
}
Create captcha Image for Servlet - Java 2D Graphics

Description

Demo Code

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