JSP中生成验证码图片

package myBean;




import java.awt.Color;


import java.awt.Font;


import java.awt.Graphics;


import java.awt.image.BufferedImage;


import java.io.IOException;


import java.io.OutputStream;


import java.util.Random;




import javax.imageio.ImageIO;






public class ImageEnsure ...{






private char mapTable[] = ...{ 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i',


'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',


'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8',


'9' };






/**//*


* 在os中输出一个大小为width,height的图片


*


*/




public String getEnsure(int width, int height, OutputStream os) ...{


if (width <= 0)


width = 60;


if (height <= 0)


height = 20;




BufferedImage image = new BufferedImage(width, height,


BufferedImage.TYPE_INT_RGB);




Graphics g = image.getGraphics();


//画背景


g.setColor(new Color(0xDCDCDC));


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


//画边框


g.setColor(Color.BLACK);


g.drawRect(0, 0, width - 1, height - 1);




String strEnsure = "";


//生成4位验证码




for (int i = 0; i < 4; ++i) ...{


strEnsure += mapTable[(int) (mapTable.length * Math.random())];


}


// 将验证码画到图片中


g.setColor(Color.BLACK);


g.setFont(new Font("Atlantic Inline", Font.PLAIN, 10));


String str = strEnsure.substring(0);


g.drawString(str, 8, 17);


str = strEnsure.substring(1, 2);


g.drawString(str, 20, 15);


str = strEnsure.substring(2, 3);


g.drawString(str, 35, 18);


str = strEnsure.substring(3, 4);


g.drawString(str, 45, 15);




// 随机产生100个干扰点




Random rand = new Random();




for (int i = 0; i < 10; i++) ...{


int x = rand.nextInt(width);


int y = rand.nextInt(height);


g.drawOval(x, y, 1, 1);


}


// 释放图形上下文


g.dispose();






try ...{


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




} catch (IOException e) ...{




e.printStackTrace();


return "";


}


return strEnsure;




}


}