Java生成验证码图片的程序

    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>