Chinaunix首页 | 论坛 | 博客
  • 博客访问: 29954456
  • 博文数量: 2065
  • 博客积分: 10377
  • 博客等级: 上将
  • 技术积分: 21525
  • 用 户 组: 普通用户
  • 注册时间: 2008-11-04 17:50
文章分类

全部博文(2065)

文章存档

2012年(2)

2011年(19)

2010年(1160)

2009年(969)

2008年(153)

分类: Java

2010-05-08 13:47:27

1.servelts代码

package bj.action;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
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.*;
public class Images extends HttpServlet {

    /**
     * Constructor of the object.
     */

    public Images() {
        super();
    }
    /** Processes requests for both HTTP GET and POST 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(0, 0, 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();
    }
    private 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);
    }

    /**
     * Destruction of the servlet.

     */

    public void destroy() {
        super.destroy(); // Just puts "destroy" string in log

        // Put your code here

    }

    /**
     * The doGet method of the servlet.

     *
     * This method is called when a form has its tag value method equals to get.
     *
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */

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

    /**
     * The doPost method of the servlet.

     *
     * This method is called when a form has its tag value method equals to post.
     *
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        out
                .println("");
        out.println("");
        out.println(" A Servlet");
        out.println(" ");
        out.print(" This is ");
        out.print(this.getClass());
        out.println(", using the POST method");
        out.println(" ");
        out.println("");
        out.flush();
        out.close();
    }
    public String getServletInfo() {
        return "Short description";
    }

    /**
     * Initialization of the servlet.

     *
     * @throws ServletException if an error occurs
     */

    public void init() throws ServletException {
        // Put your code here

    }

}


2.引用方式

    This is my JSP page.

   




调用当前的servlets进来!








系统产生的认证码:
输入上面的认证码:

 
3.验证
<%
String rand = (String)session.getAttribute("rand");
String input = request.getParameter("rand");
%>
阅读(1029) | 评论(0) | 转发(0) |
给主人留下些什么吧!~~