java生成图片验证码的示例代码

给大家分享一款java生成验证码的源码，可设置随机字符串，去掉了几个容易混淆的字符，还可以设置验证码位数，比如4位，6位。当然也可以根据前台验证码的位置大小，设置验证码图片的大小。下边是源码分享，直接看吧，很简单！

创建servlet类

import java.io.IOException;

import javax.servlet.Servlet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import com.sunjs.utils.CaptchaUtils;

public class AuthImage extends HttpServlet implements Servlet {
  static final long serialVersionUID = 1L;

  public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.setHeader("Pragma", "No-cache");
    response.setHeader("Cache-Control", "no-cache");
    response.setDateHeader("Expires", 0);
    response.setContentType("image/jpeg");

    //生成随机字串
    String captcha = CaptchaUtils.generateCaptcha(4);
    //存入会话session
    HttpSession session = request.getSession(true);
    session.setAttribute("rand", captcha.toLowerCase());
    //生成图片
    int w = 200, h = 80;
    CaptchaUtils.outputImage(w, h, response.getOutputStream(), captcha);

  }
}

创建工具类

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.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;
import java.util.Random;

import javax.imageio.ImageIO;

/**
 * 验证码
 *
 * @author sun
 * @date 2016年8月23日 上午10:12:10
 */
public class CaptchaUtils {

  // 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,L, o几个容易混淆的字符
  public static final String CAPTCHA_CHARS = "23456789ABCDEFGHJKMNPQRSTUVWXYZ";
  private static Random random = new Random();

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

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

  /**
   * 生成随机验证码文件,并返回验证码值
   *
   * @param w
   * @param h
   * @param outputFile
   * @param captchaSize
   * @return
   * @throws IOException
   */
  public static String outputCaptchaImage(int w, int h, File outputFile,
      int captchaSize) throws IOException {
    String captcha = generateCaptcha(captchaSize);
    outputImage(w, h, outputFile, captcha);
    return captcha;
  }

  /**
   * 输出随机验证码图片流,并返回验证码值
   *
   * @param w
   * @param h
   * @param os
   * @param captchaSize
   * @return
   * @throws IOException
   */
  public static String outputCaptchaImage(int w, int h, OutputStream os,
      int captchaSize) throws IOException {
    String captcha = generateCaptcha(captchaSize);
    outputImage(w, h, os, captcha);
    return captcha;
  }

  /**
   * 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;
    }
  }

  /**
   * 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 captchaSize = 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 < captchaSize; i++) {
      AffineTransform affine = new AffineTransform();
      affine.setToRotation(
          Math.PI / 4 * rand.nextDouble()
              * (rand.nextBoolean() ? 1 : -1), (w / captchaSize)
              * i + fontSize / 2, h / 2);
      g2.setTransform(affine);
      g2.drawChars(chars, i, 1, ((w - 10) / captchaSize) * i + 5, h / 2
          + fontSize / 2 - 10);
    }

    g2.dispose();
    ImageIO.write(image, "jpg", os);
  }

  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);
  }

  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() {
    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) {

    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) {

    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);
      }

    }

  }

  public static void main(String[] args) throws IOException {
//    File dir = new File("D:/verifies");
    File dir = new File("/Users/sun/Documents/captcha");
    int w = 200, h = 80;
    for (int i = 0; i < 50; i++) {
      String captcha = generateCaptcha(4);
      File file = new File(dir, captcha + ".jpg");
      outputImage(w, h, file, captcha);
    }
  }
}

配置 web.xml

<!-- 图形验证码 -->
<servlet>
  <servlet-name>AuthImage</servlet-name>
  <servlet-class>com.sunjs.controller.AuthImage</servlet-class>
</servlet>
<servlet-mapping>
  <servlet-name>AuthImage</servlet-name>
  <url-pattern>/authImage</url-pattern>
</servlet-mapping>

当然也可以增加session的过期时间，不写的话，会有默认的失效时间

<session-config>
  <session-timeout>30</session-timeout>
</session-config>

配置完成，直接启动项目访问，访问路径你们懂！！！

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