随机验证码生成

话不多说，直接上代码

package cn.stormtides.web.servlet;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.BufferedReader;
import java.io.IOException;
import java.util.Random;

@WebServlet("/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        int width=100;
        int height=50;
        //创建一个对象，在内存中存图片
        BufferedImage image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);

        //美化
        //填充背景色
        Graphics g = image.getGraphics();
        g.setColor(Color.PINK);
        g.fillRect(0,0,width,height);

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


        //写验证码
        String str="ABCDEFGHIJKLMNOPQRSTUVWXYZabcefghijklmnopqrstuvwxyz0123456789";

        Random ran=new Random();

        for (int i=1;i<=4;i++){

            //生成随机角标
            int index=ran.nextInt(str.length());
            //获取字符
            char ch=str.charAt(index);
            //写验证码
            g.drawString(ch+"",width/5*i,height/2);
        }


        //干扰线
        g.setColor(Color.green);
        for (int i=0;i<10;i++){
            int x1=ran.nextInt(width);
            int x2=ran.nextInt(width);
            int y1=ran.nextInt(height);
            int y2=ran.nextInt(height);
            g.drawLine(x1,y1,x2,y2);
        }



        //将图片输出到页面
        ImageIO.write(image,"jpg",response.getOutputStream());

    }

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

原始代码<--

前端页面代码（比较简易大家别嫌弃）:

    
    
    


    

    看不清换一张？

　　至于为什么要加时间戳，在打开页面加载图片时会存储图片路径和图片（由数字字母干扰线组成的图片），再当图片刷新时还是会加载该图片，加上一个时间戳会图片路径不会重复，从而加载新的图片，"/day15"为虚拟路径

原始代码