java生成图形验证码

首先，需要生成验证码字符串，方式很多，下面提供一种，根据指定源的方式来生成验证码

    /**     * 使用系统默认字符源生成验证码     *      * @param verifySize     *            验证码长度     * @return     */    public static String generateVerifyCode(int verifySize) {        return generateVerifyCode(verifySize, VERIFY_CODES);    }

核心方法如下：

    /**     * 使用指定源生成验证码     *      * @param verifySize     *            验证码长度     * @param sources     *            验证码字符源     * @return     */    public static String generateVerifyCode(int verifySize, String sources) {        if (sources == null || sources.length() == 0) {            sources = VERIFY_CODES;        }        int codesLen = sources.length();        Random rand = new Random(System.currentTimeMillis());        StringBuilder verifyCode = new StringBuilder(verifySize);        for (int i = 0; i < verifySize; i++) {            verifyCode.append(sources.charAt(rand.nextInt(codesLen - 1)));        }        return verifyCode.toString();    }

在指定源数据内，随机产生指定长度的字符串作为验证码，默认的源字符串为：

    // 使用到Algerian字体，系统里没有的话需要安装字体，字体只显示大写，去掉了1,0,i,o几个容易混淆的字符    public static final String VERIFY_CODES = "23456789ABCDEFGHJKLMNPQRSTUVWXYZ";

接下来输出字符串图片，这里提供接收文件和流的两种重载方式，方法如下：

1    /**     * 生成随机验证码文件,并返回验证码值     *      * @param w     * @param h     * @param outputFile     * @param verifySize     * @return     * @throws IOException     */    public static String outputVerifyImage(int w, int h, File outputFile, int verifySize) throws IOException {        String verifyCode = generateVerifyCode(verifySize);        outputImage(w, h, outputFile, verifyCode);        return verifyCode;    }
2
3    /**     * 输出随机验证码图片流,并返回验证码值     *      * @param w     * @param h     * @param os     * @param verifySize     * @return     * @throws IOException     */    public static String outputVerifyImage(int w, int h, OutputStream os, int verifySize) throws IOException {        String verifyCode = generateVerifyCode(verifySize);        outputImage(w, h, os, verifyCode);        return verifyCode;    }

上面是提供给外部调用的入口方法，生成验证码，然后输出图片，返回验证码值，输出验证码图片的两个重载方法如下：

    /**     * 生成指定验证码图像文件     *      * @param w     * @param h     * @param outputFile     * @param code     * @throws IOException     */    public static void outputImage(int w, int h, File outputFile, String code) throws IOException {        if (outputFile == null) {            return;        }        File dir = outputFile.getParentFile();        if (!dir.exists()) {            dir.mkdirs();        }        try {            outputFile.createNewFile();            FileOutputStream fos = new FileOutputStream(outputFile);            outputImage(w, h, fos, code);            fos.close();        } catch (IOException e) {            throw e;        }    }

该方法会转到另一个重载方法，也是最核心的方法：

    /**     * 输出指定验证码图片流     *      * @param w     * @param h     * @param os     * @param code     * @throws IOException     */    public static void outputImage(int w, int h, OutputStream os, String code) throws IOException {        int verifySize = code.length();        BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);        Random rand = new Random();        Graphics2D g2 = image.createGraphics();        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);        Color[] colors = new Color[5];        Color[] colorSpaces = new Color[] { Color.WHITE, Color.CYAN, Color.GRAY, Color.LIGHT_GRAY, Color.MAGENTA,                Color.ORANGE, Color.PINK, Color.YELLOW };        float[] fractions = new float[colors.length];        for (int i = 0; i < colors.length; i++) {            colors[i] = colorSpaces[rand.nextInt(colorSpaces.length)];            fractions[i] = rand.nextFloat();        }        Arrays.sort(fractions);        g2.setColor(Color.GRAY);// 设置边框色        g2.fillRect(0, 0, w, h);        Color c = getRandColor(200, 250);        g2.setColor(c);// 设置背景色        g2.fillRect(0, 2, w, h - 4);        // 绘制干扰线        Random random = new Random();        g2.setColor(getRandColor(160, 200));// 设置线条的颜色        for (int i = 0; i < 20; i++) {            int x = random.nextInt(w - 1);            int y = random.nextInt(h - 1);            int xl = random.nextInt(6) + 1;            int yl = random.nextInt(12) + 1;            g2.drawLine(x, y, x + xl + 40, y + yl + 20);        }        // 添加噪点        float yawpRate = 0.05f;// 噪声率        int area = (int) (yawpRate * w * h);        for (int i = 0; i < area; i++) {            int x = random.nextInt(w);            int y = random.nextInt(h);            int rgb = getRandomIntColor();            image.setRGB(x, y, rgb);        }        shear(g2, w, h, c);// 使图片扭曲        g2.setColor(getRandColor(100, 160));        int fontSize = h - 4;        Font font = new Font("Algerian", Font.ITALIC, fontSize);        g2.setFont(font);        char[] chars = code.toCharArray();        for (int i = 0; i < verifySize; i++) {            AffineTransform affine = new AffineTransform();            affine.setToRotation(Math.PI / 4 * rand.nextDouble() * (rand.nextBoolean() ? 1 : -1),                    (w / verifySize) * i + fontSize / 2, h / 2);            g2.setTransform(affine);            g2.drawChars(chars, i, 1, ((w - 10) / verifySize) * i + 5, h / 2 + fontSize / 2 - 10);        }        g2.dispose();        ImageIO.write(image, "jpg", os);    }

使用画板，绘制文字，背景，干扰线，设置扭曲等等，上面有详细注释，涉及到的相关方法如下：

1    /**     * 在一定范围内随机生成颜色值     *      * @param fc     * @param bc     * @return     */    private static Color getRandColor(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);    }
2
3    /**     * 随机生成颜色值     *      * @return     */    private static int getRandomIntColor() {        int[] rgb = getRandomRgb();        int color = 0;        for (int c : rgb) {            color = color << 8;            color = color | c;        }        return color;    }
4
5    /**     * 随机生成rgb值     *      * @return     */    private static int[] getRandomRgb() {        int[] rgb = new int[3];        for (int i = 0; i < 3; i++) {            rgb[i] = random.nextInt(255);        }        return rgb;    }
6
7    /**     * 使图片扭曲     *      * @param g     * @param w1     * @param h1     * @param color     */    private static void shear(Graphics g, int w1, int h1, Color color) {        shearX(g, w1, h1, color);        shearY(g, w1, h1, color);    }
8
9    /**     * X方向扭曲     *      * @param g     * @param w1     * @param h1     * @param color     */    private static void shearX(Graphics g, int w1, int h1, Color color) {        int period = random.nextInt(2);        boolean borderGap = true;        int frames = 1;        int phase = random.nextInt(2);        for (int i = 0; i < h1; i++) {            double d = (double) (period >> 1)                    * Math.sin((double) i / (double) period + (6.2831853071795862D * (double) phase) / (double) frames);            g.copyArea(0, i, w1, 1, (int) d, 0);            if (borderGap) {                g.setColor(color);                g.drawLine((int) d, i, 0, i);                g.drawLine((int) d + w1, i, w1, i);            }        }    }
10
11/**     * Y方向扭曲     *      * @param g     * @param w1     * @param h1     * @param color     */    private static void shearY(Graphics g, int w1, int h1, Color color) {        int period = random.nextInt(40) + 10; // 50;        boolean borderGap = true;        int frames = 20;        int phase = 7;        for (int i = 0; i < w1; i++) {            double d = (double) (period >> 1)                    * Math.sin((double) i / (double) period + (6.2831853071795862D * (double) phase) / (double) frames);            g.copyArea(i, 0, 1, h1, 0, (int) d);            if (borderGap) {                g.setColor(color);                g.drawLine(i, (int) d, i, 0);                g.drawLine(i, (int) d + h1, i, h1);            }        }    }

效果图如下：

官网博客地址：

https://blog.csdn.net/u010142437/article/details/103086171

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