生成验证码---checknum.jsp

最新推荐文章于 2021-03-28 20:58:27 发布

原创最新推荐文章于 2021-03-28 20:58:27 发布 · 570 阅读

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CC 4.0 BY-SA版权

本文详细介绍了一个使用Java生成验证码图片的方法，包括随机颜色选择、背景绘制、干扰线添加及数字生成等步骤，最后将生成的验证码图片整合到登录表单中。

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<%@ page language="java" contentType="text/html; charset=GBK"
    pageEncoding="GBK" import="java.sql.*"%>
    <%@ page import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GBK">
<title>Insert title here</title>
</head>
<body>
<%!
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);
}
%>
<%
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires",0);
int width=65,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 x1=random.nextInt(12);
   int y1=random.nextInt(12);
  g.drawLine(x,y,x+x1,y+y1);
}
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);
}
session.setAttribute("rand",sRand);
g.dispose();
ImageIO.write(image,"JPEG",response.getOutputStream());
out.clear();
out=pageContext.pushBody();
%>
</body>
</html>