public class SecurityCode {public enum SecurityCodeLevel {Simple, Medium, Hard};public static String getSecurityCode() {return getSecurityCode(4, SecurityCodeLevel.Medium, false);}public static String getSecurityCode(int length, SecurityCodeLevel level,boolean isCanRepeat) {// 随机抽取len个字符int len = length;// 字符集合(除去易混淆的数字0、数字1、字母l、字母o、字母O)char[] codes = { '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b','c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'm', 'n', 'p','q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'A', 'B','C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N','P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };// 根据不同的难度截取字符数组if (level == SecurityCodeLevel.Simple) {codes = Arrays.copyOfRange(codes, 0, 9);} else if (level == SecurityCodeLevel.Medium) {codes = Arrays.copyOfRange(codes, 0, 33);}// 字符集合长度int n = codes.length;// 抛出运行时异常if (len > n && isCanRepeat == false) {throw new RuntimeException(String.format("验证码长度大于字符库长度,请改小验证码位数参数 length",len, level, isCanRepeat, n));}// 存放抽取出来的字符char[] result = new char[len];// 判断能否出现重复的字符if (isCanRepeat) {for (int i = 0; i < result.length; i++) {// 索引 0 and n-1int r = (int) (Math.random() * n);// 将result中的第i个元素设置为codes[r]存放的数值result[i] = codes[r];}} else {for (int i = 0; i < result.length; i++) {// 索引 0 and n-1int r = (int) (Math.random() * n);// 将result中的第i个元素设置为codes[r]存放的数值result[i] = codes[r];// 必须确保不会再次抽取到那个字符，因为所有抽取的字符必须不相同。// 因此，这里用数组中的最后一个字符改写codes[r]，并将n减1codes[r] = codes[n - 1];n--;}}return String.valueOf(result);}
}

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.Random;
import com.sun.image.codec.jpeg.ImageFormatException;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;public class SecurityImage {public static BufferedImage createImage(String securityCode) {// 验证码长度int codeLength = securityCode.length();// 字体大小int fSize = 15;int fWidth = fSize + 1;// 图片宽度int width = codeLength * fWidth + 6;// 图片高度int height = fSize * 2 + 1;// 图片BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);Graphics g = image.createGraphics();// 设置背景色
        g.setColor(Color.WHITE);// 填充背景g.fillRect(0, 0, width, height);// 设置边框颜色
        g.setColor(Color.LIGHT_GRAY);// 边框字体样式g.setFont(new Font("Arial", Font.BOLD, height - 2));// 绘制边框g.drawRect(0, 0, width - 1, height - 1);// 绘制噪点Random rand = new Random();for (int i = 0; i < codeLength * 6; i++) {int xs = rand.nextInt(width);int ys = rand.nextInt(height);// 绘制1*1大小的矩形
            randColor(g, rand);g.drawRect(xs, ys, 1, 1);}// 干扰线for (int i = 0; i < 10; i++) {int xs = rand.nextInt(width);int ys = rand.nextInt(height);int xe = xs + 10;int ye = ys + 10;randColor(g, rand);g.drawLine(xs, ys, xe, ye);}// 绘制验证码int codeY = height - 10;// 设置字体颜色和样式g.setFont(new Font("Georgia", Font.BOLD, fSize));for (int i = 0; i < codeLength; i++) {randColor(g, rand);g.drawString(String.valueOf(securityCode.charAt(i)), i * 16 + 5,codeY);}// 关闭资源
        g.dispose();return image;}/*** 随机色* * @param g* @param rand*/private static void randColor(Graphics g, Random rand) {int red = 0, green = 0, blue = 0;red = rand.nextInt(255);green = rand.nextInt(255);blue = rand.nextInt(255);g.setColor(new Color(red, green, blue));}public static ByteArrayInputStream getImageAsInputStream(String securityCode) {BufferedImage image = createImage(securityCode);return convertImageToStream(image);}private static ByteArrayInputStream convertImageToStream(BufferedImage image) {ByteArrayInputStream inputStream = null;ByteArrayOutputStream bos = new ByteArrayOutputStream();JPEGImageEncoder jpeg = JPEGCodec.createJPEGEncoder(bos);try {jpeg.encode(image);byte[] bts = bos.toByteArray();inputStream = new ByteArrayInputStream(bts);} catch (ImageFormatException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}return inputStream;}
}