生成随机运算验证码

 

package com.xpwj.action;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class ss extends HttpServlet {

   
     //生成随机颜色
    Color getRandColor(Random random,int fc,int bc)
    {
            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 doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        HttpSession session=request.getSession(true);
        response.setContentType("image/jpeg");
        //设置页面不缓存
        response.setHeader("Pragma","No-cache");
        response.setHeader("Cache-Control","no-cache");
        response.setDateHeader("Expires", 0);


        // 设置图片的长宽
        int width=176, height=30;


        //创建内存图像
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        // 获取图形上下文
        Graphics g = image.getGraphics();


        //创建随机类的实例
        Random random = new Random();


        // 设定图像背景色(因为是做背景，所以偏淡)
        g.setColor(getRandColor(random,200,250));
        g.fillRect(0, 0, width, height);


        //备选字体
        String[] fontTypes = {"\u5b8b\u4f53","\u65b0\u5b8b\u4f53","\u9ed1\u4f53","\u6977\u4f53","\u96b6\u4e66"};
        int fontTypesLength = fontTypes.length;


        //在图片背景上增加噪点
        g.setColor(getRandColor(random,160,200));
        g.setFont(new Font("Times New Roman",Font.PLAIN,14));
        for (int i=0;i<6;i++)
        {
            g.drawString("*********************************************",0,5*(i+2));
        }

         


        //取随机产生的认证码(6个汉字)

        String[] ys=new String[]{"零","壹","贰","叁","肆","伍","陸","柒","捌","玖","拾"};
       
        //保存生成的汉字字符串
        String sRand="";
        int ys1=random.nextInt(10);
        int ys2=random.nextInt(10);
       
        String[] ysfs=new String[]{"加","减","乘"};
        String[] ysfs2=new String[]{"+","-","*"};
        int ysfIndex = random.nextInt(ysfs.length);
        int index = random.nextInt(2);
        int ysindex = random.nextInt(2);
        String ysf = "";
        String ys1s=ys1+"";
        String ys2s=ys2+"";
        //随机运算数
        switch (index) {
        case 0:
            ys1s=ys[ys1];
            break;
        case 1:
            ys2s=ys[ys2];
            break;
        }
        //随机运算符
        switch (ysindex) {
        case 0:
            ysf = ysfs[ysfIndex];
            break;
        case 1:
            ysf = ysfs2[ysfIndex];
            break;
        }
       
        int val = 0;
        switch (ysfIndex) {
        case 0:
            val = ys1 + ys2;
            break;
        case 1:
            val = ys1 - ys2;
            break;
        case 2:
            val = ys1 * ys2;
            break;
        default:
            break;
        }
        sRand=ys1s+ysf+ys2s+"=?";
        //设置字体的颜色
        g.setColor(getRandColor(random,10,150));
        //设置字体
        g.setFont(new Font(fontTypes[random.nextInt(fontTypesLength)],Font.BOLD,18 + random.nextInt(6)));
        //将此汉字画到图片上
        g.drawString(sRand,24*0+ 10 + random.nextInt(8),24);


        //将认证码存入session
        session.setAttribute("ss",String.valueOf(val));
        g.dispose();
        //输出图象到页面
        ImageIO.write(image, "JPEG", response.getOutputStream());


    }



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

}