java 验证码_彩色验证码

------------产生验证码图片的文件-----image.servlet------------------------------------------- 

 

package  untitled1;

import  java.io. * ;
import  java.net. * ;
import  javax.servlet. * ;
import  javax.servlet.http. * ;
import  java.awt. * ;
import  java.awt.image. * ;
import  java.util. * ;
import  javax.imageio. * ;
/** */ /**
 *
 * 
@author http://www.tot.name
 * 
@version
 
*/

public   class  Image  extends  HttpServlet  ... {

    
/** *//** Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
     * 
@param request servlet request
     * 
@param response servlet response
     
*/

    
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
    
throws ServletException, IOException ...{
        response.setContentType(
"image/jpeg");
        response.setHeader(
"Pragma","No-cache");
        response.setHeader(
"Cache-Control","no-cache");
        response.setDateHeader(
"Expires"0);       
        HttpSession session
=request.getSession();
        
// 在内存中创建图象
        int width=60, height=20;
        BufferedImage image 
= new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

        
// 获取图形上下文
        Graphics g = image.getGraphics();

        
//生成随机类
        Random random = new Random();

        
// 设定背景色
        g.setColor(getRandColor(200,250));
        g.fillRect(
00, width, height);

        
//设定字体
        g.setFont(new Font("Times New Roman",Font.PLAIN,18));

        
//画边框
        
//g.setColor(new Color());
        
//g.drawRect(0,0,width-1,height-1);


        
// 随机产生155条干扰线,使图象中的认证码不易被其它程序探测到
        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);
        }


        
// 取随机产生的认证码(4位数字)
        String sRand="";
        
for (int i=0;i<4;i++)...{
            String rand
=String.valueOf(random.nextInt(10));
            sRand
+=rand;
            
// 将认证码显示到图象中
            g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));//调用函数出来的颜色相同,可能是因为种子太接近,所以只能直接生成
            g.drawString(rand,13*i+6,16);
        }


        
// 将认证码存入SESSION
        session.setAttribute("rand",sRand);
        
// 图象生效
        g.dispose();
        ServletOutputStream responseOutputStream 
=response.getOutputStream();
        
// 输出图象到页面
        ImageIO.write(image, "JPEG", responseOutputStream);

        
//以下关闭输入流!
        responseOutputStream.flush();
        responseOutputStream.close();
    }

    Color getRandColor(
int fc,int bc)...{//给定范围获得随机颜色
        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);
    }

    
// <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /** *//** Handles the HTTP <code>GET</code> method.
     * 
@param request servlet request
     * 
@param response servlet response
     
*/

    
protected void doGet(HttpServletRequest request, HttpServletResponse response)
    
throws ServletException, IOException ...{
        processRequest(request, response);
    }


    
/** *//** Handles the HTTP <code>POST</code> method.
     * 
@param request servlet request
     * 
@param response servlet response
     
*/

    
protected void doPost(HttpServletRequest request, HttpServletResponse response)
    
throws ServletException, IOException ...{
        processRequest(request, response);
    }


    
/** *//** Returns a short description of the servlet.
     
*/

    
public String getServletInfo() ...{
        
return "Short description";
    }

    
// </editor-fold>
}


---------------使用验证码图片的文件---------index.jsp------------------------------------

<% ... @ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage=""  %>
< html >
< head >
< title > 认证码验证页面 </ title >
< meta  http-equiv ="Content-Type"  content ="text/html; charset=gb2312" >
< META  HTTP-EQUIV ="Pragma"  CONTENT ="no-cache" >  
< META  HTTP-EQUIV ="Cache-Control"  CONTENT ="no-cache" >  
< META  HTTP-EQUIV ="Expires"  CONTENT ="0" >  
</ head >

< body >
<% ...  
String rand = (String)session.getAttribute("rand");
String input = request.getParameter("rand");
%>
系统产生的认证码为: 
<% =  rand  %> < br >
您输入的认证码为: 
<% =  input  %> < br >
< br >
<% ...
  
if (rand.equals(input)) {
%>
< font  color =green > 输入相同,认证成功! </ font >
<% ...
  } 
else {
%>
< font  color =red > 输入不同,认证失败! </ font >
<%

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