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>