Java生成验证码图片的程序

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package test;

import java.awt.Color;

import java.awt.Font;

import java.awt.Graphics;

import java.awt.image.BufferedImage;

import java.io.OutputStream;

import java.util.Random;

import javax.imageio.ImageIO;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class ImageGenerator extends HttpServlet {

  private static final long serialVersionUID = -3938318741402322164L;

  private static Color getRandColor(int fc, int bc) {

    Random random = new Random();

    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 String charsLong = "23456789abcdefghjklmnpqrstuvwxyzABCDEFGHIJKLMNPQRSTUVWXYZ";

  private static String charsShort = "0123456789";

  private static String chars = charsLong;

  @Override

  public void doGet(HttpServletRequest request, HttpServletResponse response) {

    try {

      int charsLength = chars.length();

      response.setHeader("Pragma", "No-cache");

      response.setHeader("Cache-Control", "no-cache");

      response.setDateHeader("Expires", 0);

      int width = 70, height = 20;

      BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

      Graphics g = image.getGraphics();

      Random random = new Random();

      g.setColor(getRandColor(200, 250));

      g.fillRect(0, 0, width, height);

      g.setFont(new Font("Times New Roman", Font.ITALIC, height));

      g.setColor(getRandColor(160, 200));

      for (int i = 0; i < 35; i++) {

        int x = random.nextInt(width);

        int y = random.nextInt(height);

        int xl = random.nextInt(12);

        int yl = random.nextInt(12);

        g.drawLine(x, y, x + xl, y + yl);

      }

      StringBuilder sRand = new StringBuilder();

      String[] fontNames = { "Times New Roman", "Arial", "Book antiqua", "" };

      for (int i = 0; i < 4; i++) {

        g.setFont(new Font(fontNames[random.nextInt(3)], Font.ITALIC, height));

        char rand = chars.charAt(random.nextInt(charsLength));

        sRand.append(rand);

        g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));

        g.drawString(String.valueOf(rand), 16 * i + random.nextInt(6) + 3, height - random.nextInt(4));

      }

      g.setColor(getRandColor(160, 200));

      for (int i = 0; i < 30; i++) {

        int x = random.nextInt(width);

        int y = random.nextInt(height);

        int xl = random.nextInt(width);

        int yl = random.nextInt(width);

        g.drawLine(x, y, x + xl, y + yl);

      }

      request.getSession().setAttribute("Login_Image_Code", sRand.toString());

      g.dispose();

      try {

        Thread.sleep(100);

      } catch (Exception ex) {

      }

      OutputStream os = response.getOutputStream();

      ImageIO.write(image, "JPEG", os);

      os.flush();

      os.close();

    } catch (Exception ex) {

    }

  }

}

修改 web.xml

<servlet>

        <servlet-name>imageGenerator</servlet-name>

        <servlet-class>test.ImageGenerator</servlet-class>

    </servlet>

    <servlet-mapping>

        <servlet-name>imageGenerator</servlet-name>

        <url-pattern>/image.jsp</url-pattern>

    </servlet-mapping>

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