验证码 jsp

• 验证码的jsp实现

<%@ page contentType="image/jpeg" import="java.awt.*,
java.awt.image.*,java.util.*,javax.imageio.*" %>
<%!
    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);
    }
%>
<%
    out.clear();//这句针对resin服务器，如果是tomacat可以不要这句
    response.setHeader("Pragma","No-cache");
    response.setHeader("Cache-Control","no-cache");
    response.setDateHeader("Expires", 0);
    int width=60, 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.PLAIN,18));
    g.setColor(getRandColor(160,200));
    for (int i=0;i<155;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);
    }
    String sRand="";
    for (int i=0;i<4;i++){
        String rand=String.valueOf(random.nextInt(10));
        sRand+=rand;
        g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));
        g.drawString(rand,13*i+6,16);
    }
// 将认证码存入SESSION
    session.setAttribute("rand",sRand);
    g.dispose();
    ImageIO.write(image, "JPEG", response.getOutputStream());
%>