JSP生成驗證碼

    <%@ page contentType="image/jpeg"  
        import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*"  
    %>  
    <%!  
        Color getRandColor(int fc, int bc)  
        {  
            Random rd =  new Random();  
            if (fc > 255)  
                fc = 255;  
            if (bc > 255)  
                bc = 255;  
            int r = rd.nextInt(bc - fc);  
            int g = rd.nextInt(bc - fc);  
            int b = rd.nextInt(bc - fc);  
            return new Color(r,g,b);  
        }  
    %>  
    <%  
        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 rd = 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(new Color(255,255,255));  
        g.drawRect(0, 0, width - 1, height - 1);  

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

        for (int i=0;i<155;i++)  
        {  
             int x = rd.nextInt(width);  
             int y = rd.nextInt(height);  
             int xl = rd.nextInt(12);  
             int yl = rd.nextInt(12);  
             g.drawLine(x,y,x+xl,y+yl);  
        }  

        String sRand="";  
        for (int i=0;i<4;i++){  
            String rand=String.valueOf(rd.nextInt(10));  
            sRand+=rand;  
            g.setColor(new Color(20+rd.nextInt(110),20+rd.nextInt(110),20+rd.nextInt(110)));  
            g.drawString(rand,13*i+6,16);  
        }  
        session.setAttribute("rand",sRand);  

        g.dispose();  

        ImageIO.write(image, "JPEG", response.getOutputStream());  
        out.clear();  
        out = pageContext.pushBody();  
    %>  

    <img src = "code.jsp"/>