java web验证码生成总结(包括servlet、jsp)

一、使用纯Servlet实现验证码.

(1)在web.xml配置:

<servlet>      
    <servlet-name>image</servlet-name>      
    <servlet-class>org.test.web.AuthImage</servlet-class>      
</servlet>      
     
<servlet-mapping>      
    <servlet-name>image</servlet-name>      
 <url-pattern>/authImage</url-pattern>      
</servlet-mapping> 

 

(2)servlet源码:

public class AuthImage extends HttpServlet      
{      
     
    private static final String CONTENT_TYPE = "text/html; charset=gb2312";      
    //设置字母的大小,大小      
    private Font mFont = new Font("Times New Roman", Font.PLAIN, 17);      
    public void init() throws ServletException      
    {      
        super.init();      
    }      
    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);      
    }      
     
    public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException      
    {      
        response.setHeader("Pragma","No-cache");      
        response.setHeader("Cache-Control","no-cache");      
        response.setDateHeader("Expires", 0);      
        //表明生成的响应是图片      
        response.setContentType("image/jpeg");      
              
        int width=100, height=18;      
        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(1, 1, width-1, height-1);      
        g.setColor(new Color(102,102,102));      
        g.drawRect(0, 0, width-1, height-1);      
        g.setFont(mFont);      
     
        g.setColor(getRandColor(160,200));      
     
        //画随机线      
        for (int i=0;i<155;i++)      
        {      
            int x = random.nextInt(width - 1);      
            int y = random.nextInt(height - 1);      
            int xl = random.nextInt(6) + 1;      
            int yl = random.nextInt(12) + 1;      
            g.drawLine(x,y,x + xl,y + yl);      
        }      
     
        //从另一方向画随机线      
        for (int i = 0;i < 70;i++)      
        {      
            int x = random.nextInt(width - 1);      
            int y = random.nextInt(height - 1);      
            int xl = random.nextInt(12) + 1;      
            int yl = random.nextInt(6) + 1;      
            g.drawLine(x,y,x - xl,y - yl);      
        }      
     
        //生成随机数,并将随机数字转换为字母      
        String sRand="";      
        for (int i=0;i<6;i++)      
        {      
            int itmp = random.nextInt(26) + 65;      
            char ctmp = (char)itmp;      
            sRand += String.valueOf(ctmp);      
            g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));      
            g.drawString(String.valueOf(ctmp),15*i+10,16);      
        }      
     
        HttpSession session = request.getSession(true);      
        session.setAttribute("rand",sRand);      
        g.dispose();      
        ImageIO.write(image, "JPEG", response.getOutputStream());      
    }      
    public void destroy()      
    {      
    }      
}    

(3)页面显示:

<img src="authImage"/>

 二、使用纯jsp实现验证码

<%@ page language="java" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*"    
     contentType="image/jpeg" pageEncoding="UTF-8"%>   
  
  
<%  //设置页面不缓存   
   response.setHeader("Pragma","No-cache");   
   response.setHeader("Cahce-Control","no-cache");   
   response.setDateHeader("Expires",0);   
   //在内存中创建图片   
   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();   
   //设置背景颜色   
   g.setColor(new Color(160,200,100));   
   g.fillRect(0,0,width,height);   
   //设置字体   
   g.setFont(new Font("Times New Roman",Font.PLAIN,18));   
   //随机产生50条干扰线，使图形中的验证码不易被其他的程序探测到   
    g.setColor(new Color(160,200,200));   
   for(int i=0;i<50;i++)   
   {   
     int x=random.nextInt(width);   
     int y=random.nextInt(height);   
     int x1=random.nextInt(width);   
     int y1=random.nextInt(height);   
     g.drawLine(x,y,x+x1,y+y1);   
   }   
   //随机产生验证码（6位数字）   
   String sRand="";   
   for(int i=0;i<6;i++)   
   {   
     String rand=String.valueOf(random.nextInt(10));   
     sRand+=rand;   
     //将验证码显示到图象   
     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);  //////将产生的验证码存储到sesson中   
   g.dispose();   
   ImageIO.write(image,"JPEG",response.getOutputStream());   
   out.clear(); //***********   
   out=pageContext.pushBody();//**********   
 %>