用户登录验证码

Question

我新手用到这块。用户登录验证码如何实现？求大神讲解下。有详细代码及注释的更好

Answer 1

<%@ page language="java" import="java.util.*" import="java.awt.*,java.awt.image.*,com.sun.image.codec.jpeg.*" %>
    <%!
        Color getColor(int a,int b){
          int n=b-a;
          Random rd=new Random();
          int cr=a+rd.nextInt(n);
          int cg=a+rd.nextInt(n);
          int cb=a+rd.nextInt(n);
          return new Color(cr,cg,cb);
        }
    %><%
       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_BGR);
       Graphics g=image.getGraphics();
       Random random=new Random();
       g.setColor(getColor(200,250));
       g.fillRect(0,0,width,height);
       g.setFont(new Font("Times New Roman",Font.BOLD,18));
       g.setColor(getColor(160,200));
       for(int i=0;i<160;i++){
         int x=random.nextInt(width);
         int y=random.nextInt(height);
         int x1=random.nextInt(12);
         int y1=random.nextInt(12);
         g.drawLine(x,y,x+x1,y+y1);
       }
       String number=String.valueOf(1000+random.nextInt(8999));
       String name=request.getParameter("name");
       session.setAttribute("name",number);
       g.setColor(getColor(20,130));
       int x=(int)(width*0.2);
       int y=(int)(height*0.8);
       g.drawString(number,x,y);
       g.dispose();
             
       JPEGImageEncoder encoder=JPEGCodec.createJPEGEncoder(response.getOutputStream());
       out.clear();
       out = pageContext.pushBody();
       encoder.encode(image);
       out.close();        
    %>