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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:
/*** 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;}
/*** 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:
/*** 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);}
/*** 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;}
/*** 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;}
/*** 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);}
/*** 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);}}}
/*** 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: