如何用自定义标签实现图片验证码？

vipwalkingdog 2012-01-16 04:08:16

如题。



public class RandomPic extends TagSupport

{

	@Override

	public int doEndTag() throws JspException

	{

		

		int width=100, height=18, r1, g1, b1;

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

		Graphics g = image.getGraphics();

		Random random = new Random();

		r1=200+random.nextInt(50);

		g1=200+random.nextInt(50);

		b1=200+random.nextInt(50);

		g.setColor(new Color(r1, g1, b1));

		g.fillRect(1, 1, width-1, height-1);

		g.setColor(new Color(102,102,102));

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

		r1=160+random.nextInt(40);

		g1=160+random.nextInt(40);

		b1=160+random.nextInt(40);

		g.setColor(new Color(r1, g1, b1));

		for (int i=0;i<155;i++)

		{

		    int x = random.nextInt(width - 1);

		    int y = random.nextInt(height - 1);

		    int xl = random.nextInt(6) + 1;

		    int yl = random.nextInt(12) + 1;

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

		}

		for (int i = 0;i < 70;i++)

		{

		    int x = random.nextInt(width - 1);

		    int y = random.nextInt(height - 1);

		    int xl = random.nextInt(12) + 1;

		    int yl = random.nextInt(6) + 1;

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

		}

		String sRand="";

		for (int i=0;i<6;i++)

		{

		    String tmp="";

			  long itmp = 0;

			  char ctmp = '\u0000';

			  switch ((int)Math.round(Math.random() * 2))

			  {

				   case 1:

					    itmp = Math.round(Math.random() * 25 + 65);

					    ctmp = (char)itmp;

					    tmp = String.valueOf(ctmp);

					    break;

				   case 2:

					    itmp = Math.round(Math.random() * 25 + 97);

					    ctmp = (char)itmp;

					    tmp = String.valueOf(ctmp);

					    break;

				   default :

					    itmp = Math.round(Math.random() * 9);

					    tmp = String.valueOf(itmp);

			  }

		    sRand += tmp;

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

		    g.drawString(tmp,15*i+10,15);

		}

		

		g.dispose();

		

		//已经配置好tld了。应该这样直接输出图片？前提是图片不用保存在服务器上。

		/**

		 * <Random:RandomPic/>

		 * 上面一句会输出一张图片，

		 * 

		 * 

		 */

		//ImageIO.write(image, "jpeg", pageContext.getOut());

		return EVAL_PAGE;

	}