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一段生成验证码图片的程序

2008-02-26 09:43 447 查看
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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