JSP中产生数字验证码源码

    数字验证码是一种最常用的验证字符码形式，以下为数字实现的JSP源码：    Num.jsp

    <%@ page contentType="image/jpeg" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %>

    <%!

    Color getRandColor(int cc,int bb)

    {

    Random random = new Random();

    if(fc>255) cc=255;

    if(bc>255) bb=255;

    int r=cc+random.nextInt(bb-cc);

    int g=cc+random.nextInt(bb-cc);

    int b=cc+random.nextInt(bb-cc);

    returnnew Color(r,g,b);

    } //获取随机颜色

    %>

    <%

    response.setHeader("Pragma","No-cache");

    response.setHeader("Cache-Control","no-cache");

    response.setDateHeader("Expires", 0);

    int width=80; //定义验证码图片的长度

    int height=30; //定义验证码图片的宽度

    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.PLAIN,18));

    //定义字体形式

    g.setColor(getRandColor(160,200));

    for (int i=0;i<155;i++)

    {

    int i_x = random.nextInt(width);

    int i_y = random.nextInt(height);

    int i_xl = random.nextInt(12);

    int i_yl = random.nextInt(12);

    g.drawLine(i_x,i_y,i_x+i_xl,i_y+i_yl);

    }

    //用线条画背景

    String s_Rand="";

    for (int i=0;i<4;i++)

    {

    String rand=String.valueOf(random.nextInt(10));

    s_Rand+=rand;

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

    g.drawString(rand,13*i+6,16);

    }

    //产生4位随机码

    session.setAttribute("rand",s_Rand);

    //将验证码存入Session中

    g.dispose();

    ImageIO.write(image, "JPEG", response.getOutputStream());

    //输出验证图片

    out.clear();

    out = pageContext.pushBody();

    %>