用java写了一个带扭曲特性的验证码程序。

原文：http://www.tashan10.com/java-sheng-cheng-niu-qu-de-yan-zheng-ma/

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;

import org.springframework.stereotype.Component;

/**
 * CheckCode.java
 * 
 * @author King<br/>
 *         
 * @Description 验证码生成类
 * @since 1.0.0
 * @Date 2012-2-29下午1:50:25
 */
@Component
public class CheckCode {
    private int width = 102;
    private int height = 28;
    private int codeCount = 4;

    private Random random = new Random();

    /**
     * 验证码图片
     */
    private BufferedImage buffImg;
    /**
     * 验证码字符串
     */
    private String checkCodeStr;

    /**
     * 
     * @Description:创建验证码对象
     * @since 1.0.0
     * @Date:2012-3-1 上午10:26:20
     * @return CheckCode
     */
    public CheckCode createCheckCode() {
        CheckCode checkCode = new CheckCode();
        checkCode.setCheckCodeStr(createRandomCode());
        checkCode.setBuffImg(disturb());
        return checkCode;
    }

    /**
     * 
     * @Description:随机产生的验证码
     * @since 1.0.0
     * @Date:2012-3-1 上午10:20:05
     * @return String
     */
    private String createRandomCode() {
        StringBuffer randomCode = new StringBuffer();

        String strRand = null;
        int xx = width / (codeCount + 1);
        int codeY = height - 4;
        char[] codeSequence = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J',
                'K', 'L', 'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W',
                'X', 'Y', 'Z', '2', '3', '4', '5', '6', '7', '8', '9' };

        Graphics2D graphics = graphicsInit();
        graphics.setColor(createColor());

        for (int i = 0; i < codeCount; i++) {
            strRand = String.valueOf(codeSequence[random.nextInt(32)]);
            randomCode.append(strRand);

            graphics.drawString(strRand, (i + 1) * xx, codeY);
        }

        return randomCode.toString();
    }

    /**
     * 
     * @Description:创建颜色
     * @since 1.0.0
     * @Date:2012-2-29 下午4:47:14
     * @return Color
     */
    private Color createColor() {
        Color color[] = new Color[10];
        color[0] = new Color(113, 31, 71);
        color[1] = new Color(37, 0, 37);
        color[2] = new Color(111, 33, 36);
        color[3] = new Color(0, 0, 112);
        color[4] = new Color(14, 51, 16);
        color[5] = new Color(1, 1, 1);
        color[6] = new Color(72, 14, 73);
        color[7] = new Color(65, 67, 29);
        color[8] = new Color(116, 86, 88);
        color[9] = new Color(41, 75, 71);

        return color[random.nextInt(10)];
    }

    /**
     * 
     * @Description:绘制类初始化
     * @since 1.0.0
     * @Date:2012-3-1 上午10:17:52
     * @return Graphics2D
     */
    private Graphics2D graphicsInit() {
        Graphics2D graphics = buffImgInit().createGraphics();
        graphics.setColor(Color.WHITE);
        graphics.fillRect(0, 0, width, height);
        graphics.setFont(new Font("Fixedsys", Font.BOLD, height - 2));
        graphics.drawRect(0, 0, width - 1, height - 1);
        return graphics;
    }

    /**
     * 
     * @Description:BufferedImage初始化
     * @since 1.0.0
     * @Date:2012-3-1 上午11:07:18
     * @return BufferedImage
     */
    private BufferedImage buffImgInit() {
        buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        return buffImg;
    }

    /**
     * 
     * @Description:绘制干扰特性
     * @since 1.0.0
     * @Date:2012-3-1 上午11:45:32
     * @return BufferedImage
     */
    private BufferedImage disturb() {
        drawDisturbLine(buffImg.createGraphics());
        return twistImage();
    }

    /**
     * 
     * @Description:画干扰线使图象中的认证码不易被其它程序探测到
     * @since 1.0.0
     * @Date:2012-2-29 下午4:28:23
     * @param graphics
     *            void
     */
    private void drawDisturbLine(Graphics2D graphics) {
        graphics.setColor(Color.BLACK);
        int x = 0;
        int y = 0;
        int xl = 0;
        int yl = 0;
        for (int i = 0; i < 15; i++) {
            x = random.nextInt(width);
            y = random.nextInt(height);
            xl = random.nextInt(20);
            yl = random.nextInt(10);
            graphics.drawLine(x, y, x + xl, y + yl);
        }
    }

    /**
     * 
     * @Description:正弦曲线Wave扭曲图片
     * @since 1.0.0
     * @Date:2012-3-1 下午12:49:47
     * @return BufferedImage
     */
    private BufferedImage twistImage() {
        double dMultValue = random.nextInt(7) + 3;// 波形的幅度倍数，越大扭曲的程序越高，一般为3
        double dPhase = random.nextInt(6);// 波形的起始相位，取值区间（0-2＊PI）

        BufferedImage destBi = new BufferedImage(buffImg.getWidth(),
                buffImg.getHeight(), BufferedImage.TYPE_INT_RGB);

        for (int i = 0; i < destBi.getWidth(); i++) {
            for (int j = 0; j < destBi.getHeight(); j++) {
                int nOldX = getXPosition4Twist(dPhase, dMultValue,
                        destBi.getHeight(), i, j);
                int nOldY = j;
                if (nOldX >= 0 && nOldX < destBi.getWidth() && nOldY >= 0
                        && nOldY < destBi.getHeight()) {
                    destBi.setRGB(nOldX, nOldY, buffImg.getRGB(i, j));
                }
            }
        }
        return destBi;
    }

    /**
     * 
     * @Description:获取扭曲后的x轴位置
     * @since 1.0.0
     * @Date:2012-3-1 下午3:17:53
     * @param dPhase
     * @param dMultValue
     * @param height
     * @param xPosition
     * @param yPosition
     * @return int
     */
    private int getXPosition4Twist(double dPhase, double dMultValue,
            int height, int xPosition, int yPosition) {
        double PI = 3.1415926535897932384626433832799; // 此值越大，扭曲程度越大
        double dx = (double) (PI * yPosition) / height + dPhase;
        double dy = Math.sin(dx);
        return xPosition + (int) (dy * dMultValue);
    }

    /**
     * 
     * @Description:将图像进行输出到文件
     * @since 1.0.0
     * @Date:2012-3-1 上午11:56:19
     * @param pathName
     * @return String
     */
    public String createImgFile(String pathName) {
        File file = new File(pathName);
        if (file.isFile() && file.exists()) {
            file.delete();
        }
        try {
            ImageIO.write(buffImg, "jpeg", file);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return pathName;
    }

    public BufferedImage getBuffImg() {
        return buffImg;
    }

    public void setBuffImg(BufferedImage buffImg) {
        this.buffImg = buffImg;
    }

    public String getCheckCodeStr() {
        return checkCodeStr;
    }

    public void setCheckCodeStr(String checkCodeStr) {
        this.checkCodeStr = checkCodeStr;
    }

    public int getWidth() {
        return width;
    }

    public void setWidth(int width) {
        this.width = width;
    }

    public int getHeight() {
        return height;
    }

    public void setHeight(int height) {
        this.height = height;
    }

    public int getCodeCount() {
        return codeCount;
    }

    public void setCodeCount(int codeCount) {
        this.codeCount = codeCount;
    }

}

大致思路是，将验证码字符和图片封装到类CheckCode，外部程序使用createCheckCode创建一个CheckCode对象，然后就可以获取到验证码字符串和图片。 测试代码如下：

import org.junit.Assert;
import org.junit.Test;

/**
 * CheckCodeTest.java
 * @author King<br/>
 *        
 * @Description 描述一下这个文件
 * @since 1.0.0
 * @Date 2012-2-29下午1:51:13
 */
public class CheckCodeTest {
    @Test
    public void testCheckCodeCreate(){
        CheckCode checkCode=new CheckCode();

        checkCode=checkCode.createCheckCode();
        String checkCodeStr=checkCode.getCheckCodeStr();
        System.out.println(checkCodeStr);
        Assert.assertNotNull(checkCodeStr);
        Assert.assertEquals(4, checkCodeStr.length());

        Assert.assertNotNull(checkCode.getBuffImg());

//      for (int i = 0; i < 10; i++) {
//          checkCode=checkCode.createCheckCode();
//          String checkCodeStr=checkCode.getCheckCodeStr();
//          System.out.println(checkCodeStr);
//          Assert.assertNotNull(checkCodeStr);
//          Assert.assertEquals(4, checkCodeStr.length());
//          
//          String filePathName="C:\\test"+i+".jpg";
//          checkCode.createImgFile(filePathName);
//          File file=new File(filePathName);
//          
//          Assert.assertTrue(file.exists());
//      }
    }
}