package com.test.utils;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

public class Main1
{

    public static void main(String[] args)
    {
        String verifyCode = VerifyCodeUtils.generateVerifyCode(4);
        FileOutputStream fos = null;
        try
        {
            File file 
 
= new File("d:\\temp\\aa");
            if (!file.exists())
            {
                System.out.println("file not exists, create it ...");
                file.mkdirs();
            }

            fos = new FileOutputStream(file.getPath()+"\\rj2.jpg");

            VerifyCodeUtils.outputImage(150, 80, fos, verifyCode);
        } 
 
catch (Exception e)
        {
            e.printStackTrace();
        } finally
        {
            try
            {
                fos.close();
            } catch (IOException e)
            {
                e.printStackTrace();
            }
        }
    }
}

package com.test.utils;

import
 
 java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;
import java.util.Random;
import java.util.concurrent.ThreadLocalRandom;

import javax.imageio.ImageIO;

public class VerifyCodeUtils
{

    // 使用到Algerian字體，系統裏沒有的話需要安裝字體，字體只顯示大寫，去掉了1,0,i,o幾個容易混淆的字符
    private static final String VERIFY_CODES = "23456789ABCDEFGHJKLMNPQRSTUVWXYZ";

    /**
     * 使用系統默認字符源生成驗證碼
     * 
     * @param verifySize
     *            驗證碼長度
     * @return
     */
    public static String generateVerifyCode(int verifySize)
    {
        return generateVerifyCode(verifySize, VERIFY_CODES);
    }

    /**
     * 使用指定源生成驗證碼
     * 
     * @param verifySize
     *            驗證碼長度
     * @param sources
     *            驗證碼字符源
     * @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();
    }

    /**
     * 輸出隨機驗證碼圖片流,並返回驗證碼值
     * 
     * @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;
    }

    /**
     * 輸出指定驗證碼圖片流
     * 
     * @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);// 設置邊框色
        g2.fillRect(0, 0, w, h);

        Color c = getRandColor(200, 250);
        g2.setColor(c);// 設置背景色
        g2.fillRect(0, 2, w, h - 4);

        // 繪制幹擾線
        Random random = new Random();
        g2.setColor(getRandColor(160, 200));// 設置線條的顏色
        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);
        }

        // 添加噪點
        float yawpRate = 0.05f;// 噪聲率
        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);// 使圖片扭曲

        g2.setColor(getRandColor(100, 160));
        int fontSize = h - 4;
        Font font = new Font("宋體", 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);
    }

    private static Color getRandColor(int fc, int bc)
    {
        Random random = ThreadLocalRandom.current();
        
        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);
    }

    private static int getRandomIntColor()
    {
        int[] rgb = getRandomRgb();
        int color = 0;
        for (int c : rgb)
        {
            color = color << 8;
            color = color | c;
        }
        return color;
    }

    private static int[] getRandomRgb()
    {
        Random random = ThreadLocalRandom.current();
        int[] rgb = new int[3];
        for (int i = 0; i < 3; i++)
        {
            rgb[i] = random.nextInt(255);
        }
        return rgb;
    }

    private static void shear(Graphics g, int w1, int h1, Color color)
    {
        shearX(g, w1, h1, color);
        shearY(g, w1, h1, color);
    }

    private static void shearX(Graphics g, int w1, int h1, Color color)
    {
        Random random = ThreadLocalRandom.current();
        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);
            }
        }

    }

    private static void shearY(Graphics g, int w1, int h1, Color color)
    {
        Random random = ThreadLocalRandom.current();
        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);
            }
        }

    }
}

生成驗證碼